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I think we need a bigger pump?

Posted by Rio_Grande none (My Page) on
Mon, Aug 26, 13 at 12:31

On our nft setup I am running 2 1/4 inch inlets to each channel. That gives good fluid spread in the first 3 or so inches, if I use 1 I don't get good spread for 6 or 8 inches. The problem is when I guessed at the flow rate needed I guessed wrong. When I added the next 3 channels I barely have any pressure from the closest 1/4 inch tube near the pump. The pump flows 900 and some gpm. Seems that there should be plenty to run 15 1/4 in tubes to flood a thin film in the troughs.

I can move the pump closer to that end, it currently pumps up 3 feet and 18 feet around the table. I can move the pump to the other end of the table and the pump would pump up 6 feet and then across the end of the table which is 10 feet.
The pump is rated for 8 or 9 feet I can't remember exactly.

Will that work or do I need a bigger pump?


Follow-Up Postings:

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RE: I think we need a bigger pump?

I run into this problem with 3 troughs also. I don't believe it is the pump size so much at the configuration of the lines.
If you run two troughs they'll both work fine, but with three it seems the fluid dynamics favors first the farthest outlet down the line, then it favors the outlet nearest the pump.
My workaround (and I'm not saying this is the best fix) is to "prime" the line each time I start the pump back up. by priming, I simply place my finger over one of the outlets (nearest or farthest) and hold it blocked until the flow starts to come out the middle outlet. after I remove my finger, everything works fine.
I have my ideas about why it works this way but they're not scientific enough that I would even attempt to explain it. See if that works for you.
I also have no idea what will happen with more than three troughs.


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RE: I think we need a bigger pump?

900 gpm at what height? I'd think there's quite a bit of head pressure in NFT. In my Aeroflo-18 there is three spray lines 1/4" (I think) with six holes. The pump that came with it (which seems more than necessary) has the following specs:
Lift=11 Feet, Pressure=5 PSI, Volume=790 GPH.

My guess is the gph on your pump is falling off dramatically with height (pressure).


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RE: I think we need a bigger pump?

I think 1/4" lines are too small. I use 1/2" cpvc and a 1/8" drill bit for holes. I know GH uses a smaller line, but I like mine a lot better. They flow better, and they don't clog as much.

When plants get big and the roots start to fill up the chamber, the amount of water flowing down the tube is more important than the spraying. The ends of the tubes can get stagnant, and that's also where the lines clog first. I plumb a valve into the end of the cpvc spray line in case I ever want more flow at the end of the tube.


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RE: I think we need a bigger pump?

Griz that worked to get them going.

I had all kinds of trouble today. Got to the farm and the resivour was dry, I expected a leak but never could find one. I have a few drain joints that drip slightly, but this has never happened before. I think I will use PVC glue to make them solid. Just not sure how long it needs to sit so it dosent mess the plants up.

I also looked more closely at the pump tonight it is a 575 gpm at 6 feet, the way I have it set up even though it is only 3 feet of head, there is still 18 ish feet of push around at the top of that. I am going to move the pump and resivour to the inlet side of the table and move the drain as necessary. That will make the over all head height about 3 feet and the push at the top 8 feet. I think I will run the line above as mentioned by someone here and that will get some help from gravity.

How do you use PVC in this application? I am running 3/4 in supply line that we use as header for drip irrigation. Only complaint I have is it drips on occasion.


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RE: I think we need a bigger pump?

  • Posted by nil13 z21 Mt. Washington L (My Page) on
    Tue, Aug 27, 13 at 11:05

900 gpm? I think you mean 900 gph. a 3/4" pipe at mains pressure will only put out about 12gpm.


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RE: I think we need a bigger pump?

Take a gander at this picture. The last 4 in particular. The whole thing is fed with 1/2" PVC.
outdoor_sys_2013

Had I known early what I learned later, I wouldn't have run the pvc through the top but had it simply enter from the end. That would have meant less elbows. But it is what it is.

One thing I learned this year is that a trough can get backed up if you have a plant to close to the input end. On one of the troughs I had to relocate the nearest plant because it was slightly backing up the water causing it to slowly drip out the high end. It took me a couple of days to figure it out.


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RE: I think we need a bigger pump?

Your right nil I typed it wrong.


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RE: I think we need a bigger pump?

I am up to 7 troughs and that is about half the number I have planned.

I see what you mean about the PVC. I don't like the 1/4 in input, two is better but has the problems I mentioned. I have a clear water pump here that I was contemplating using, but I would have to run a relief valve. Not fond of the over pressure, volume is great, but I don't want it blasting down the trough.


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RE: I think we need a bigger pump?

Rio,

I couldn't see how you did it without problems mounting below the channels, that's why I mentioned it before. If I did your design, I would have tried to mount the irrigation main above and get a gravity assist by simply pumping up to the main and letting it basically leak down with small overpressure, whatever is left.

Each little hose increase the pressure for what is essentially the friction caused by *pushing* the water. So going from above has a double benefit. Once the water is up there, using larger drip lines as suggested, gravity not only delivers, it also takes the lion's share of friction off your pump's head pressure.

One other thing to keep in mind ... shorten the hoses wherever possible. since that is creating a lot of the drag your pump fights, even if it is above.


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RE: I think we need a bigger pump?

Thanks,

I am chasing loosing resivour fluid, I tent two days and diddnt loose any that I am aware of, overnight I lost about 10 gallons. There has to be a leak somewhere.

One other thing I observed is with the lower flow the water at the end drips back. I wonder if there is some dripping back the rail. If the flow is faster it dosent happen. That would explain why it has suddenly appeared.


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RE: I think we need a bigger pump?

I know exactly what you mean about dripping back at low flow. Since I'm still not up and running quite yet I don't have a place to test (I worry a lot that your drip back problem will soon be mine too).

I don't know if your material will allow it but here is my theory on how I will fix it if it crops up to me, that is, the problem of the water clinging to the edge of the channel outlets (if they are uncapped): Bend the bottom surface of the pipe at a sharp angle right at the outlet. You know, like when you wrap someones gift, the last flap you can make a small slit on each side and fold it at a sharp angle. Just the last few millimeters. Or just cap the whole thing and cut another drain hole in the bottom (opposite plant holes of the channel). My second idea pretty much isn't a great one since if you are like me you probably don't want to cut up your plastic more than minimum and need to carefully think through whether it is what you want to be stuck with, unless you trim the channel length later, but design wise it really would eliminate the problem since the down pipe would just be vertical and could be cut off however you want to allow water to spash back into the res or return manifold depending on the sort of design.

Wow, 10 gallons is a lot of water, unless there is some obvious crack you overlook, really doubtful, the only place it sneaks out has to be there or somehow upon return to the res in a similar sneaky way to wrap around.

Have you measured the output to see if you can keep at least a liter per minute per channel?

Hey, another way less destructive, just an idea, is to put a small guide plastic blocking the channel end except for an opening in one place. That way if you are lucky to have good spread still by the end, it will get corraled up and effectively stream out instead of sheet out (no puns intended).


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RE: I think we need a bigger pump?

Perhaps you raising up your reservoir with some bricks underneath or some thing similar to reduce the head.
Also try connecting both ends of the drip line header to the pump to help equalize the flow, add more feeds to the middle of the header to further even out the flow. That pump should work for that few lines.
The grow cube and plant roots should help spread the flow in the bottom of the channel once they start growing.


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RE: I think we need a bigger pump?

I had already heated and bent the end of the trough,

What I did today, and it solved the flow problem for now. I extended the drain and moved the resivour effectively reducing the head by 10 feet and 2 90deg fittings. Flow is good now, still not sure where the water went. It lost another 2 gal over night. I have it all put together and will see how it looks in in the morning. The flow back with that volume of flow was nil, so I am hoping that that was it and it is over.

Thanks for the replies, time for bed.


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RE: I think we need a bigger pump?

Hope you find no leaks in the morning. I was coming back to say to raise the res, but SD has that well covered and you have solved a lot meanwhile. Also one other way to fix it in case it ever comes in handy without the heat bending we both liked. Instead of messing with the PVC or corraling the water to a stream, it might be simpler to attach a couple of inches of some spreader mat in the end of the channel outlet that will hang over and drip all by itself without messing with the plastic. You could just cut a piece of polyester out of an old sweatshirt in a pinch and I bet that would solve all the water-cling problems.

Thanks for not being shy about this discussion. Lots of good tips from everyone. So far I plan to use smooth railpost without any spreader, but to be honest I don't know how much "thin film" quality I can get. I like Grizz's little pebbled ground he did under his setup and was thinking about something like that, but here the ground feels like it's moving each time I walk on it which really leaves me wondering.


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RE: I think we need a bigger pump?

I like and appreciate all the replies here. The system is at my parents farm under a shade house where they grow lettuce. So sometimes I get all excited to work on it but can't. So posting here curbs some of that.

I think this pump has the power to work at this configuration. The only thing that might mess that up is I plan to burry a barrel for a resovour of I do that will add 2 ish more foot of head to the pump. Last night I actually had to put pipe clamps on the barb fittings to keep one from dripping, those same fittings don't leak in our underground irrigation at 15psi so this may be putting out more than that,

Hope that leak is solved today. Thanks for the replies.


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RE: I think we need a bigger pump?

You can simply increase the slope of your channels bay placing a 2x4 beneath the inlet end. this will increase the flow and prevent the drip back.
I made my 90° with a piece of the channel. I cut it about 16" long then cut off one wide face so the horizontal(-ish) channel ran past the edge approximately 1" and simply screwed them together. Note: I didn't do this to prevent leakage but to keep the fluid contained and keep the light out.
Pupilla that is not pebbles beneath my setup. I just dump mulch there to kill the weeds.


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RE: I think we need a bigger pump?

Speaking of weeds, my area under the troughs is growing like crazy. I am thinking the water had to be running back. It is all right under the channels and nowhere else.
I called the farm today and dad said it diddnt look like it lost a drop of water overnight. I will take a few pix today. I need to put nutrient in the water, I held off last few days looking for the leak. I am about out of ph down and need to order some.
Which do you prefer granular or liquid? I need to cut some costs and depending on how concentrated the granular is, it might be the way to go.


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RE: I think we need a bigger pump?

Perhaps you raising up your reservoir with some bricks underneath or some thing similar to reduce the head.
Also try connecting both ends of the drip line header to the pump to help equalize the flow, add more feeds to the middle of the header to further even out the flow. That pump should work for that few lines.
The grow cube and plant roots should help spread the flow in the bottom of the channel once they start growing.


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RE: I think we need a bigger pump?

Rio

You can usually save money if you buy concentrated acids (85% phosphoric, 70% Nitric, ~90% Sulfuric). The question is whether you can deal with and tolerate the risks of handling them.

I'm currently checking into sulfuric acid which is not commonly sold, but a perfectly valid and sometimes desirable pH down. They all cost in the same neighborhood, but nitric comes out more expensive since it is a "mono"-acid and a little harder to ship.

The point I'm getting to is I see a possible low cost opportunity if you are willing to try Rooto Professional drain opener which appears to be in the 90-98% range of sulfuric acid. I am not recommending it either way, since I need to get some more "contaminant" composition info before I can be even sure this product is for sure ok.

But at under $15 a quart if you can get it locally at a plumbing or hardware place, it will be nearly the same ballpark of capacity as about a gallon of the ~20% phosphoric being sold as concentrated pH Down (maybe it's 30% I don't recall at the moment).

Just throwing it out there as an area to check out to potentially reduce costs and if anyone had a comment or experience with that product With acids the expensive part is shipping, so finding a concentrated acid source locally if you are ok to handle it is always going to save big time; no matter what acid you choose. Shipped, a liter of any concentrated one is usually about $30. I know there are limits on how much nitric that may be shipped, so that makes that a bad option. If you go phosphoric, though, concentrated 85 can be bought by the gallon.

Always add acid to water when diluting since it is more dense and has less tendency to splash rather than sink. Things can get dangerously and instantly hot when diluting, so also it is done s-l-o-w-l-y.

I don't have a comment on the powder since I haven't looked at what is in it, it probably contains (sodium?) salts of the acids and probably citric acid salts too which may give a formula with more buffering ability. Not really what I'm after, but I'd like to hear some comments form anyone who gets economical good results with it too.


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RE: I think we need a bigger pump?

Rio

You can usually save money if you buy concentrated acids (85% phosphoric, 70% Nitric, ~90% Sulfuric). The question is whether you can deal with and tolerate the risks of handling them.

I'm currently checking into sulfuric acid which is not commonly sold, but a perfectly valid and sometimes desirable pH down. They all cost in the same neighborhood, but nitric comes out more expensive since it is a "mono"-acid and a little harder to ship.

The point I'm getting to is I see a possible low cost opportunity if you are willing to try Rooto Professional drain opener which appears to be in the 90-98% range of sulfuric acid. I am not recommending it either way, since I need to get some more "contaminant" composition info before I can be even sure this product is for sure ok.

But at under $15 a quart if you can get it locally at a plumbing or hardware place, it will be nearly the same ballpark of capacity as about a gallon of the ~20% phosphoric being sold as concentrated pH Down (maybe it's 30% I don't recall at the moment).

Just throwing it out there as an area to check out to potentially reduce costs and if anyone had a comment or experience with that product With acids the expensive part is shipping, so finding a concentrated acid source locally if you are ok to handle it is always going to save big time; no matter what acid you choose. Shipped, a liter of any concentrated one is usually about $30. I know there are limits on how much nitric that may be shipped, so that makes that a bad option. If you go phosphoric, though, concentrated 85 can be bought by the gallon.

Always add acid to water when diluting since it is more dense and has less tendency to splash rather than sink. Things can get dangerously and instantly hot when diluting, so also it is done s-l-o-w-l-y.

I don't have a comment on the powder since I haven't looked at what is in it, it probably contains (sodium?) salts of the acids and probably citric acid salts too which may give a formula with more buffering ability. Not really what I'm after, but I'd like to hear some comments form anyone who gets economical good results with it too.


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RE: I think we need a bigger pump?

Been thinking about that. I am going to have to buy another bottle of the prepaid stuff as I am down to about a teaspoon, once I have the backup I can start playing with other options. I have a good friend who uses bulk acid in his drain to waist greenhouse set up. He has an injector that does it all automatically. I don't need to be that fancy yet lol.

To report back, no observable loss of fluid today, so I balanced the ph and added nutrient to about 540 ppm, will check it again tomorrow and take it up to 800 if all is well. I added a few pix of new resivour I need to bury and the new set up.
 photo image_zps6e9d3587.jpg
 photo image_zpsf68ae636.jpg


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RE: I think we need a bigger pump?

Top on my list for tomorrow is getting at least 4 more rails in place. I have starts that need to go in the system and some that are really crowding. I think I will make these 8 inches apart. The 6 inches are not enough room for this lettuce.

Thinking about starting some romaine, it grows vertically and dosent spread much.


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RE: I think we need a bigger pump?

On acid,
A fellow who used to post here a lot, greystoke, I believe,, said you could used battery acid as pH down and could buy it at an auto parts store. He didn't recommend getting it out of a battery but rather buying replacement fluid.
As far as nitric acid goes, be careful with it. It can be explosive and I think it has federal ATF restrictions because of said explosiveness. It is a base component of C4.


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RE: I think we need a bigger pump?

Hi Griz

I would discourage the use of battery grade concentrated sulfuric acid (and that is why I didn't suggest it). However, upfront - my opinion is only based on suspicion.

Batteries are lead based, and have many other dangerous toxins. This says nothing of the sulfuric acid being sold for them. However in concentrating acids inevitably there are heavy metal ions that get into it.

If the application is automotive, lead is no problem and there is no specification or assay necessary since it is being used for what is essentially a toxic battery system.

Plumbing, on the other hand may offer more protection since we are dealing with pipes, but it's not a sure thing either, but I'd take an assay of a plumbing application much more seriously.

As for nitric acid, it is not explosive unless you want to mix up a batch of explosives with it. It is a strong oxidizer, but then again hydrogen peroxide is used for the most explosive rocket fuel, and regular household bleach at 5-8% eats flesh at at least as fast a rate as nitric acid. IMO, the cleanest pH down is sold by Techaflora, and it is Nitric acid. Also, nitric is a standard pH down for many high end growing operations. Here, is 4 liters for $30. Shipping will be $15-20 more. Personally I think the Technaflora product is the highest quality on the market ;-)

http://www.megagrowers.com/technaflora-ph-down-4-l/

None of these things are safe so it is best just to read about what you get and err on the side of caution. There are issues with shipping any oxidizer in liquid form considering how boxes get thrown around. Explosive? Let's talk about explosive agricultural calcium nitrate which contains a percent of ammonium nitrate that is really explosive.

***
Calcium nitrate (from some official sounding link):
Can cause explosions in contact with combustible dusts or vapors; occasionally explosive by shock or friction. Sensitive to mechanical impact.

Unstable. Exposure to heat may result in build-up of dangerous pressures. A strong oxidizer, reacts violently upon contact with many organic substances, particularly textile and paper.

Mixtures of the nitrate with organic materials may be explosive.

***

My point isn't to say don't be careful ---- *do* *do* *do*! I've used nitric acid all my life. It produces the highest quality etching in metal work and arts, minerology, electronics, etc. I personally find it about the same degree of care as concentrated sulfuric.

The only time I ever had an accident with acid it was with 37% hydrochloric acid that splashed right in my eye. Had it been sulfuric I would have been blinded for sure, and nitric, most likely. Washed it out and no problem whatsoever. Visine is weak hydrochloric acid btw. Wear glasses ....


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RE: I think we need a bigger pump?

Rio, that really looks sharp now, your new channel drain (I think it is new as I just noticed it) is the same design I'm looking for a good pipe to do. Glad the leak is history, keep the updates coming, especially those nice pictures. Lucky you, scored a nice drum. My local Pepsi distributor kindly told me to take a hike when I asked for one. New policy he claimed is they must shred them for recycling.


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RE: I think we need a bigger pump?

Everyone used to have 20 of those blue drums laying around, now days they are 20.00 if you can find them.

I am looking for the big ibc totes now, not having much luck.


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RE: I think we need a bigger pump?

Acid, part two to help you compare the market leader products for phosphoric acid and nitric acids to buying them from a non-hydroponic supplier.

The MSDS for both Technaflora (nitric) and General Hydroponics (phosphoric) is purposely vague about the acid concentration in their product. But if you study all the data, you can narrow much more accurately what you get.

The result is:
Technaflora's nitric acid pH down:
6-7% Nitric acid

GH's phosphoric acid down:
10-16% Phosphoric acid

To be fair, there is an additional forty cents worth of citric acid and ADP in the Gen Hydro liter product which will add EC, ammonia, even more phosphate and the corresponding buffering capacity whether you want it or not.

If buying concentrated acids, the markup on the Technaflora product is much lower and in that sense a more resonable purchase. It costs about twice as much as its retail shipped concentrated acid content. The GH product is about a 4-5X markup, and when you buy it cheap often arrives leaking (check the Amazon reviews)


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RE: I think we need a bigger pump?

So at 16%, I can find 85% so in a quart of 85 I would get roughly 5x the product as compared to GH at 16%? Quarts are within 2.00 of each other. I think I will try it if I can find it local.


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RE: I think we need a bigger pump?

Tell me about those drums and the good old days. Somehow recycling them means we might have to buy new ones from places like uline while the soda companies annual reports blab about how many ugly park benches, such an essential commodity they've produced, instead of helping the community manage its water resources like good corporate neighbors. You're right about the barrel $20 'fees' LOL. Around here, those are usually when someone at the distributor knows a guy (his cousin) who gets them under the table and runs a little racket. So does anyone know a guy who knows a guy around NE Fla to slip him a $20 and be done with it finally ;-(. Uline has the IBC big boys, but I think you want a more affordable option.


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RE: I think we need a bigger pump?

Ya, worst case I will get 6 mil plastic and some 2x6 and make tanks, but that isint really what I want. We pay 50 each for the ones we use to haul our irrigation water. That is another thought on the acid. I am contemplating ph adjusting our irrigation water. I am learning things in hydro research that might help our dirt plants as well.


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RE: I think we need a bigger pump?

You got the acid calculation right (probably when the dust settles you'll get the acid for 30% the price of the commercial product) so long as you buy the commodity acid, best by the gallon. Just remember it doesn't have the buffering capability other than being a "multi" acid, so you will actually use more (I don't like buffering by arbitrarily adding ammonium nitrogen like GH, so for me not getting it is actually a plus, but others have very respectable opposite views)

If you want to screw around with the buffer just buy $6 of citric acid and MAP fertilizer and toss in up two ounces each per liter home-brewed 'pH Down'. But be sure you aren't already running excessive ammonia.


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RE: I think we need a bigger pump?

Wonder if that is why my lettuce really looked good the day after my first ph adjustment.


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RE: I think we need a bigger pump?

I buy 2.5 gallons of 100% Phosphoric acid for about $100 at Crop Production Services (CPS). That's more than most can use in years but it should give you a sense of how much you are overpaying at the hydro shops.


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RE: I think we need a bigger pump?

I buy 2.5 gallons of 100% Phosphoric acid for about $100 at Crop Production Services (CPS). That's more than most can use in years but it should give you a sense of how much you are overpaying at the hydro shops.


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RE: I think we need a bigger pump?

I buy 2.5 gallons of 100% Phosphoric acid for about $100 at Crop Production Services (CPS). That's more than most can use in years but it should give you a sense of how much you are overpaying at the hydro shops.


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RE: I think we need a bigger pump?

Hi SD,

Yup that's the good stuff. Concentrated 85% Food grade phosphoric acid goes for $5-10 per gallon if you used higher volumes to give you an idea how much CPS is making. 100% phosphoric acid is a crystalline solid and rather expensive. If you put it on a table in front of your eyes it will dessicate its surroundings until it contains up to 14% water. That's the 85% stuff you are buying in liquid jugs.


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RE: I think we need a bigger pump?

And regarding the Sulfuric Acid, who could argue with a product called "Rooto Pro" ;-) even though it is actually "rooto professional drain cleaner". and other names, looks like they are simply repackagers from bulk for the plumbing supply market.

Watch them as there seem to be two varieties,
1) Virgin
2) Inhibited

I'm not sure what is being inhibited so the virgin sounds better. In any case you can pick up a quart of the stuff, it is

93.2% concentrated virgin sulfuric acid
the rest: water

available at Menards if you happen to live nearby a Menards, for $6.98. There's way more pH lowering capacity in that concentrated little quart than an entire gallon of the commercial phosphoric and nitric acids sold by the hydro companies.


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RE: I think we need a bigger pump?

If you read the packaging on just about anything, it will say "it is a violation of Federal law to use this product in a manner inconsistent with its labeling."

People laugh at that as a joke. And it's true that no one is going to come and arrest you. That label, and that law, exist for the sake of product liability lawsuits.

So what, right? Well, the joke is on the consumer, because any labelled product need only be 99% pure. Chemical companies actually introduce toxic waste into chemicals that are not sold for human consumption, because they make money "disposing" of it that way. Battery acid, a commonly used PH down, is a good example. You can bet that any battery acid you buy is going to contain up to 1% lead. It's too profitable for the chemical companies to pass up; they trade each other in toxic wastes like lead so they can dispose of them this way.

And if anyone poisons themselves by using a product inconsistent with its labeling, then they can't sue, because they were violating Federal law. That's good for the chemical industry; I'm sure their lobbyists helped write the law.


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RE: I think we need a bigger pump?

Understanding that Robbie, would purchasing "food"grade help get a safer product for hydroonic application?

I was thinking about the attached product.

Here is a link that might be useful: Amazon acid.


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RE: I think we need a bigger pump?

Hi Cole

When commerce, marketing and science get mixed up you can bet what comes out is about as accurate as trusting a quote from shoddy journalism.

I would definitely steer clear of battery acid, not because of any conspiracy, but simply because the final application is toxic, not for human contact and ends up in a toxic waste dump. For that reason, sulfuric acid sold for lead-acid batteries that is off spec is a perfect market to sell the lowest quality.

If I were a sulfuric acid supplier I would sell the higher grade for the applications requiring it and the lower grade where it wasn't a problem. Same as a farmer harvesting cherries, send the big premium stuff to the guy who pays for it and the reject size to the processor making cherry ice cream. Not the same risk, but certainly the same concept!

That's why I'm excited about this Rooto Professional Drain Opener product which I am still personally investigating to get to the bottom of the application information, which is whether the highly touted "93% Virgin Sulfuric Acid" is suitable for use in potable water pipes. If so, it likely will be consistent with our application which is simply hydroponics plumbing which carries non-potable water (the nute solution).

To fully appreciate this one must understand the fertilizers are all agricultural grade, or technical grade. While the marketeers at some of the hydro companies can fool some of the customers some of the time, they can't fool all of us all of the time.

Really, I'm with Cole on this as far a label liability. Unfortunately it is more complicated than just to blame the chemical industry though. My experience working in it was under the strictest assays imaginable. However when product was off spec it was simply sold to a customer who said it was a spec he could use.

Where I would draw a distinction, the problem is not principally with the large chemical producers. They sell the chemicals at a small fraction of what the marketers charge for mixing a few grams here and there or simply repackaging and slapping on a label.

It is through the marketers that representations are made or distorted with marketing tactics that can really push the envelope or exceed fair advertising, and in some cases be downright misrepresentations.

Next time you put two drops of food grade pH down acid into 5 gallons of your nutrient solution ... You have to ask yourself, does a fraction of a gram of this technical grade acid need to be food grade, when 30 grams of powdered salts are only technical grade?

The proof is only after looking over an assay of the lot the acid came from., and going through the contaminants one by one and not forgetting to ask if the assay covers all the contaminants of interest.

For example, when comparing food grade phosphoric acid to technical grade phosphoric acid (PA), one thing we want to ask about is ppm's of lead+heavy metals. Agreeing with Cole's comment about sometimes small differences, but cutting the producers a bit of slack I simply ask the specification, which is something like this.

Technical grade 85% PA (US) 10 ppm (max, typical 4 ppm):
Food Grade 85% PA (US): 5 ppm max, typical 3 ppm
Food Grade 85% PA (PR China): 10 ppm
Food Grade 85% PA (Taiwan): 5 ppm


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RE: I think we need a bigger pump?

Rio

That product is from Duda Diesel, not Amazon, since they are a reputable company, you don't needs to pay the few dollars extra. Just order directly. That's where I got the PA I currently have, except if you buy a gallon it is half the rate considering shipping.


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RE: I think we need a bigger pump?

Ok, just found them on the web.


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RE: I think we need a bigger pump?

I was unable to go to the farm today, but dad mentioned he added a gallon of water to it today to keep it topped off. Which leads me to a question.

How much water will160 lettuce plants in. Various stages of growth take up a day and how much should I expt to liaise to evaporation?


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RE: I think we need a bigger pump?

Thanks for keeping the forum active.

That has got to be a question that could have any answer depending on the temperature profile day & night, humidity, light conditions, mean age of the plants and tons of other stuff.

If you want to know what the plants take 'up in a day', whatever the total weiht gain is is a very close estimate of what they take up since the leaves are like 95% water.

An average plant may average 5 grams weight increase each day (180 g head divided by 35 days). So 160 plants times 5 grams/day each is 800 grams going into your plants weights daily, call it 760 if you like for the actual water. That's a bottle of plant wine (0.75 liters) they drink each day.

So the rest is evaporation.

There are two kinds of evaporation:
1) transpiration
2) non-plant evaporation from the system

Transpiration is necessary for healthy plants and greater than the "uptake" above under the most comfy conditions.


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RE: I think we need a bigger pump?

Guess that isint far apart.

Tomorrow is tomatoe harvest and processing. With at least a truckload of tomatoes calling my name I doubt I will get any other work done. Sunday is about half that volume of green beans. So Monday I am going to load the new ebb and flow nursery. Hope to see roots in a few days as opposed to a few weeks. We will see. I will probably have another 300 dumb questions then.
I am using black poly orchard tube for a header. It is very rigid and if I have to pull out one of the push in fittings I usually can't get it seal back up. Is there another recommended type of tube for this? I was going to go PVC if I can't find flex line that will reseal.
Thanks for he intelligent conversation on this.
Grizz where did you go?


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RE: I think we need a bigger pump?

Too many posts so this may have been mentioned (though probably not): If you want some of the blue plastic 50 gallon drums, go to a nearby trucking company. They generally contain soap used for washing the trucks. The company will probably give them to you to save having to recycle them. That is where I used to get mine until my Father in law retired.


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RE: I think we need a bigger pump?

Never thought of that. We had several laying around the farm that were in surprisingly good condition.

Looks like we are loosing just over a gallon a day. I am going to bury that drum and if the current usage continues I hopefully will only have to top it off once a week.

I picked up 5 more troughs today and ordered the phosphoric acid. I sure hope this lettuce sells! Need to make this dough back!


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RE: I think we need a bigger pump?

Note to self: Follow up that truck drum suggestion!

Rio,
For 160 plants averaging say 40% mature weight, one gallon, no sweat, can easily be transpired through the leaves in a day. The system evaporation may not figure much in that total loss, so if that happens after burying the res don't be surprised.

I did a little random reading and if I am not completely misunderstanding, transpiration in lettuce may be equal to more than half of the leaves' weights themselvs normally daily.


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RE: I think we need a bigger pump?

Some revisions, still looks getto, I have to fix the sun shade for further expansion though
 photo image_zps88c04b93.jpg
Partially buried resivour
 photo image_zps443d7207.jpg
Product, almost there, figure no more than 2 weeks to harvest the first 94 heads.

 photo image_zps5c5c8de5.jpg


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RE: I think we need a bigger pump?

You should pack that excess dirt around the reservoir for further heat buffering.


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RE: I think we need a bigger pump?

Great idea, dad mentioned that yesterday. It is grey clay, little water and it will be like stucko


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RE: I think we need a bigger pump?

Another evolution...
 photo image_zps1e4ef571.jpg


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RE: I think we need a bigger pump?

Shoehorned 2 more rails in there. The way we are running it now I need to build another the same size.


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RE: I think we need a bigger pump?

Almost there!
 photo image_zps5c25f12e.jpg


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RE: I think we need a bigger pump?

Nice. Are you using a spreader mat in the channels? Is that gutter for channels or something special?


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RE: I think we need a bigger pump?

No spreader mat. It is actually downspout modified. Seems to work fairly well.


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RE: I think we need a bigger pump?

Interesting. I am using flat fence post covers and even with the thing perfectly level, the water still just makes a single conga line down... I put in the fleece/PET material and it works - but you cant easily relocate or remove a plant without disturbing its neighbors..

I think I am going to try a channel with no mat, and just use plants that have really good roots from the nursery channel...


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