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DIY Aero Tub

Posted by TheMasterGardener1 none (My Page) on
Mon, May 9, 11 at 21:25

Hi. I have a few questions about diy.

Do I need a ppm meter even if I used RO or distilled?

Do my plants care what ppm they get?

So if I use half strength nutrient and ph it will I be ok?

Thank you. And any thoughts about diy would good. I am switching to diy aeroponics because it saves alot of water and nutrients. I know with aero you have to be particular about your ppm and ph so any info would be great thanks.

Should I get a ppm/ph meter?

Or will the reg test kit be fine?


Follow-Up Postings:

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RE: DIY Aero Tub

Whether or not you want to use an EC meter really has to do with how long you want to keep using/adding to your rez between nutrient changes.
You'll still need to check / adjust pH no matter what water you use.
Plants will only grow as fast as the least available component. If that happens to be a very dilute nutrient, your plants grow more slowly (and sometimes splindly)That's not to say too much is better.
Are you going to use true aeroponics (high pressure - small droplet size) or what we on the forum refer to as soakaponics (low pressure - sprinkler size droplets). If soakaponics, i can say it's very effective and would encourage you. If true aero, I can't help much and would refer you to hex. He seems to have done a lot more of that.


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RE: DIY Aero Tub

Its best to start with low pressure and work your way up.
Low pressure aero is the cheapest and easiest to diy. Its more of a spray than a mist and the nutes are usually recirculated due to the high flow rate so you`ll need to adjust ph/ec and occasionally dump the res like other hydro methods but it does a good job.
High pressure aero gives you more control and delivers real mist but involves more hardware than just a pump and a timer. The lower flow makes run to waste a viable option so there is no need to chase ph/ec, just refill the tank when its empty.
Air atomising aero is the least common and the most expensive. It allows you to control everything including the droplet size and flowrate. Run to waste is the way to go with this one as it has a lower flow than the high pressure.


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"High pressure aero gives you more control and delivers real mist but involves more hardware than just a pump and a timer. The lower flow makes run to waste a viable option so there is no need to chase ph/ec, just refill the tank when its empty"

Would you say this is a good way?
I was thinking of the recirculateing low pressure mist but I may look into that.

Thanks for the info.


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Hi MG
There isnt much of a difference in the overall costs between low and high pressure. Low pressure is cheaper to set up but costs more in power and nutrients. High pressure costs more to set up but is cheaper on power and nutrients.
Depending on the layout, high pressure usually requires fewer nozzles as the fine mist covers better than a coarse spray.

Looking at the bigger picture, high pressure allows for run to waste which is easier to manage than a recirculating res, less potential for heating, nutrient imbalance or contamination as nothing comes back.


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RE: DIY Aero Tub

The true mist aero is not forgiving of power loss. The roots get a fine hair like fuzz that will dry and die much faster than the low pressure sprinklers.
"Doing 10 with no Chance of Parole"


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Power loss isn`t an issue if you choose the right system design, one that can be run from a 20w solar panel/rv deep cycle battery indefinitely. High pressure aero roots are a lot more resilient than most people imagine.
Low pressure aero tends to form a thick layer of roots on the floor of the chamber which rely on the high flowrate for aeration. A prolonged power outage would be equally detrimental especially if the roots were sitting in warm water with a low oxygen content when the power goes out.

I guess in a worse case, you could throw a bucket of water into the low pressure system or manually spray the roots once an hour in the high pressure system :)


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Just wanted to say that anything electrical can break down. Solar panels can break, especially in high winds when things go flying around. Wiring can short out, especially if connections get wet, and/or even some rodents like to chew through them. Also battery's can die without any warning. I worked at sears auto center, starting off in the battery's and tires department (before moving to breaks and front end), and I have seen my share of failed battery's. Just an FYI, deep cycle battery are not designed to maintain a charge like regular car battery's are, deep cycle's last longer if they are drained completely before recharging. Not saying it wouldn't be a good setup (especially if care is taken to keep it maintained), just saying it's far from foolproof.


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RE: DIY Aero Tub

Hi HH,
Car batteries are designed to provide a huge amount of current to turn the starter motor, a deep cycle "leisure type" battery is a better choice for this application as they are designed to be repeatedly discharged. In any case, most people would use a mains transformer to provide 12v dc with the battery hooked up to a relay to take over in case of a power outage.

The solenoids and cycle timer draw 1.4A per day,(based on 1300 misting cycles per day) so even a very ropey battery could run the system for a while.

Moisture has little effect with 12v dc, it will happily work even underwater:) Wiring shouldnt short if its installed correctly.


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RE: DIY Aero Tub

I agree that the deep cycles are designed to be discharged repeatedly, that's in fact exactly how they are different. But the solar panel will continually charge the battery, so it wont actually be discharging much at all. Unless you have it set on a regulator that only allows the solar panels to charge the battery's when the voltage drops below a certain point (like say 5-6 volts). Sure a regular car battery is designed for the high current draw of the starter, but the alternator keeps the battery charge maintained the rest of the time, much like the solar panels will do. Just saying that deep cycles are designed to be discharged then charged, and they last the longest when they are completely discharged, then charged back up again. Compared to put on a charger (the solar panel in this case) that maintains a relevantly consent charge.


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RE: DIY Aero Tub

Let me end this all with one word......generator.

Thanks for the info guys. I think I may just end up doing deep water culture dwc for most of my plants and try out aero with a few others. I am only experienced with soilless so I dont think I should get right into aeroponics.


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With the low current drain you could get away with dry cell batteries for backup or even nicads :)
I was just illustrating the point that the old myth of a power outage killing everything in an aero system is untrue.
The other common aero myth is good old pump failure, which imho is more likely to happen with low pressure than high pressure. A pump running 24/7 has more chance of failing than one that runs for a few minutes every few hours or a few minutes once a week, depending on the system design.

A power outage doesnt affect the pump if its not running :)


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Yea it is important to keep up on a back up plant though. So do you think it it s wise for me to go with dwc rather than aeroponics? I see the dwc may use a little more water and nutrients but it looks a more forgiving you could say.


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Discounting the effects of power outages, which dont happen that often anyway, you could go for either dwc or low pressure aero
With dwc you need to keep the water well aerated and not too warm.
With low pressure aero its just the water temp, so i guess you could say that dwc is less forgiving.


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Not sure why there is so much attacking what people say, especially when It's true. Fog fed plants die before sprinkler fed plants in a power failure. hex2006 u'r a rude, smart mouthed azzhole.


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I suggest you count to ten, do some research based on the tried and tested system description that follows and rethink your answer.

My hp setup uses a 16-bar (232psi)accumulator charged to 230psi with a pressure reducer on the outlet providing 90psi constant pressure. The accumulator and any 12v dc source is sufficient to run everything indefinitely..its not reliant on power from the grid in any way, shape or form.
The pump used to charge the 16-bar accumulator is a manual hydrostatic test pump capable of 60-bar (882psi) pressure..it doesn`t require any power.
Your sprinklers stop working in a power outage, mine aren`t affected so your plants will keel over and die long before mine do.
Its probably best you build, test and gain a lot more experience with aero before wading in, that way you wont look like a clueless muppet :)


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So I like to see this argument lol ;)

Anyway about the aero. So what your saying is the best thing would be low pressure diy. I wanted to make invidiul tubs should I just do the mother bucket idea because then I will only have to buy one water chiller? Thanks for the info I learn so much from this. Again thanks.


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Hi MG
Its not an argument,its simply a statement of fact :)

The best thing is whatever you are comfortable with, personally i would opt for an approach that didnt require running a chiller but no doubts someone will chime in to say that you absolutely need to use a chiller for low pressure aero and dwc lol


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We like the low pressure rotating sprinklers; they ( for us) deliver a much heavier coverage to the roots and inspire nicer root development. Using them with an inclosed unit takes some thinking and experimenting, as the roots can never touch the rotators. We started with the 360 deg. Nozzles and the are good but need higher pressure for good spray. IMHO
"Doing 10 with No Chance of Parole"


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So do you use a chiller? Need to keep water at 60f right? In a room that is 80f I think I will need a chiller and dont want to buy many for diff. tubs so I think I will make a mother bucket or res. Thanks keep posting some thoughts if you have anymore.


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I'm not sure what the deal is, but personally I didn't find any of hex's statements to be rude at all. And I personal don't feel he was rude or attacking me in any of his replays to any statements I made. In fact I found the replays quite useful. One case in point is the reply about low voltage working underwater. This is true, and I have some low voltage accent lights in the front yard that do just that when it rains. Though the wiring needs to be installed correctly (as hex said), and the wiring can still be damaged (depending on it's setup) from severe weather, and/or animals. But hex never said otherwise.

Also I personally didn't feel attacked with hex's reply's about using deep cycles, fact is nothing he said is untrue about them. I just wanted to point out that a solar panel is a charger that will continually charge the battery (unless a regulator is used to allow it to drain before charging). I'm not saying that deep cycles shouldn't be used, or that a regular car battery would be a better choice. Either battery will work, and both types of battery's should be cared for, checking water levels, checking hydrometer readings for bad cells, keeping the battery's at room temp. All will help prolong the life of either type of battery.

Personally I would like to see hex's high pressure aeroponic setup. He really seems to have the experience, and the most efficient setup/design that I have herd about from anyone, and I plan to build something like it in the future. Though I will have some trial and error finding the right parts, adjusting the water delivery (tubing size, flow needed for the amount of mister heads, cycle times etc.). But it wouldn't be any fun otherwise.


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hex
I didn't realize you used a manual pump to charge your accumulator. what volume does the accumulator hold and how often do you charge it? I seem to recall you saying once a day.
Is that correct?


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Hi HH
You shouldnt have any trouble building something like this as long as you size the accumulator to match the system and buy the right pump. A 16-bar accumulator may be difficult to find at a reasonable price where you are. A 10-bar or 8-bar tank will work but need 2x-3x the capacity of a 16bar tank respectively. I would use 25-bar tanks (368psi) if 25-bar pressure regulators weren`t so expensive.

As an example,
60gal chamber. A 6.6gal 16-bar accumulator will run 4x 1gph nozzles at a constant 90psi on a 1 second/3 minute timing cycle for a little over 7 days. The pump will recharge the accumulator in 5-10 minutes.
Power usage:
12v cycle timer and a 12v solenoid: ~6w @ 12v (0.5A) over a 24hr period.
Compared to a small airpump for dwc or a pond pump for low pressure aero, high pressure aero uses very little power.


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RE: DIY Aero pump

Hi grizz
I had to think way outside the box to come up with the idea of using a manual pump. No heat,no noise and no power needed.
It solves all of the common issues with high pressure aero with the bonus the hardware lasts forever as its doing very little work.


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"I had to think way outside the box to come up with the idea of using a manual pump. No heat,no noise and no power needed.
It solves all of the common issues with high pressure aero with the bonus the hardware lasts forever as its doing very little work."

Again one word......generator-The electric generator was first made in 1790 by a man named Aloisio Galvani. Over the years, scientists improved the practical and theoretical parts of the equipment. In 1831, another man (named Michael Faraday), discovered the operating principal of electromagnetic generators. The principle is now called Faraday's Law.

The first workable units though for generating power were created by Nikola Tesla. He is created with the creation of alternating current, which requires a method of creation. He is also credited with the creation of the motor which is very similar in construction to the generator

Read more: http://wiki.answers.com/Q/Who_invented_the_generator#ixzz0UjGP7Jw9

Hahaha. Thats what happens when you take the forum. ;)


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MG
why would you need a generator when the total power used is only 6 watts at 12v dc? A fully charged small 60A/H deep cycle battery could run the system for around 4 months before you`d need to recharge it.

The generator could solve the power outage issue, (a ups may be cheaper) but it doesn`t reduce or negate the risk of a pump failure especially if you use the pump without an accumulator.


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You are right. I dont have a generator but when I start my aeroponic system I will consider getting a battery as a back up. Thanks because I prob. would have never thought to get a back up and I would be in the dark spraying my plants roots with a bottle untill the power came back ;)

Do you have to run a chiller if your room/air temp gets above 80f? I would think the water would get up to 70f at that temp but if I keep my rooms temps at 75f or less will I need a water chiller?
Thanks.


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RE: DIY Aero Tub

hex. This is just everyday stuff I talk about. And we are not going to say what you say is wrong as you have proven that you are a genius over and over.
We use a chiller on a common rez. and shoot for 65 deg. The results of good temp. on root delivery will become obvious very quickly.
We went through several blow-ups in a row and lost all of our plants. Faulty pumps,storms,meter failure, & power loss.
We were polished off by what we think was some soil born pathogen that took off due to plants weakened condition. We are restarting with only seeds and no outside started plants. We bought a larger chill unit than was recommended and are not sorry for that decision.
"Doing 10 with no Chance of Parole"

Here is a link that might be useful: just chillin


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RE: DIY Aero Tub1

Thanks. So I want to do a low pressure aeroponic tubs it looks the best. How much is a cheap chiller because I want to just have invidual tubs rather than one rez. I will not have a huge system maybe 3-4 35 gal totes. Is it worth getting that many chillers or should I do a primary rez.? Any thought would be good thanks.


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Hi Soyousee
If the chiller solved the problem and is working for you setup,it was worth spending the money on.
I personally don`t use a chiller as its unnecessary for low flow high pressure aero. I run drain to waste nutes so theres no pump related res heating or solar heated nutes returning to the res. The intermittant fine misting creates evaporative cooling inside the root chamber which is self regulating as a higher chamber temperature increases the cooling effect.
Coarse spray doesn`t have the same effect so using cooler nutes is the next best option but less cost effective, especially if the pump adds heat and warm nutes return to the res.

Run to waste is worthwhile in a lot of cases as it provides pathogens with one less route into a res. If one chamber does get infected it can`t spread to any others as they are not linked by a common reservoir.


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hex

Thank you. See this is why I ask peoples experience so I can start with the right one with trial and error.

So you just have a main rez the you have you water and nutrients in with a cover and that stays cool? Being drain to waste Does that require a drain in the room? Being I am used to soilless but I am quik to learn I think I will go with a highpressure aero. I will look up some high pressure systems that best fit my needs. Any suggestions?


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Depending how large the system is you may not need a res at all except when recharging the accumulator, i just mix the required amount of nutes in a bucket.
How long a given size of accumulator will run for in terms of time depends on a number of factors, namely, the number of nozzles in the system, their flowrate and the timing cycle.
The tank pressure also affects the nozzle flowrate, (the tank has a higher pressure when freshly charged, lower pressure when its almost empty) but you can counter this by using an adjustable pressure regulator to provide constant outlet pressure regardless of what pressure is in the accumulator. I run tanks at 230psi-90psi with the regulator set to 90psi.
The components required depend entirely on the system design so its not easy to make specific recommendations but in very general hardware terms, you`ll need a pump of some description (electric or manual) capable of charging the accumulator to the desired pressure, an accumulator of sufficient capacity to provide the required recharging interval (a day, a week etc), solenoid(s),a cycle timer, nozzles and possibly a pressure regulator if the tank pressure warrants using one. It sounds more difficult than it is.
High pressure aero uses very little water so a drain in the room isnt essential, any small container to catch the run off will do.


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hex,
how do you get the nutrients into the accumulator? is there a separate valve to add the liquid or does it run through the pump?
Also, is there a set volume a mister can cover at 90 psi over a set time interval? Or is it just trial and error? I'm Just trying to figure out how many plants could be grown given a certain accumulator volume. It seems that if you found an affordable accumulator you could calculate how many plants it'll grow over a certain recharge interval on say a 4/180 cycle. I'd like to give it a try, but I don't want to invest in a $400 accumulator until I've given it a couple of runs.
Each mister head requires X amount of pressure, so with less heads, you could use a lower pressure rating? A lot to ponder here.
Thanks for your input.


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Hi Grizz,
The nutrients get pumped in under pressure. Picture the accumulator attached to center leg of a tee fitting, the pump connects to one side of the tee via a shut off valve (allowing pump removal and tank draining). The pressure regulator/solenoid (s) connnect to the other side of the tee.
I remove the pump after charging the tank and run straight r/o through it to clear the nutes so the pump is clean ready for next time.

A 4/180 cycle with high pressure is likely to soak everything in range of the nozzles, you shouldn`t need to use more than a 1 or 2 second misting. My cycle timers misting times range from 0.3-1.7 seconds.
Nozzle specifications will (sometimes) give you the misting pattern, for example, 60degree full cone as well as the flowrate for various pressures.

"Each mister head requires X amount of pressure, so with less heads, you could use a lower pressure rating?"
Not too sure what your asking, the pressure will be the same for 1 nozzle or 10 nozzles, only the flowrate will change :)

The accumulator will deliver as much flow as the pipe diameter will carry. When the solenoid opens, water is delivered instantly at tank pressure. A pump cant react fast enough to deliver a sub 1 second misting.

The accumulator will be the biggest headache as they are very expensive in the states for some reason. $400 is a ridiculous price unless its a very large tank, a 25L (6.6 us gal)16-bar costs $77 including the shipping here.


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I don't really understand what is meant by "16-bar". I am guessing it is the amount of mister heads, but that doesn't explain this statement "a 25L (6.6 us gal)16-bar costs $77."

The way I understand it works is fairly simple in design, with a metal tank the center of it (called the accumulator). Being that a metal tank would be needed to contain the amount of pressure. And the metal tank is filled with the nutrient solution, and compressed air is pumped in from above to pressurize the tank. And a simple portable emergency air compressor you plug into your car cigarette lighter to re-inflate your tires would be able to sufficiently pressurize the tank (and happens to be 12 volt DC to boot). Though maybe not to 200+psi, but to well above 90 psi. When the pressure drops the compressor kicks on again, just like the compressor I had in my garage for my air tools (it would kick on when the psi dropped below 100 psi).

Then at the bottom of the metal tank is a water line that goes to the misters. Connected inline with that water line is a solenoid flow valve, that opens and closes at what ever cycle time the timer is set for. Thus control's the flow to the misters. To change or add more nutrients you would just unplug the compressor, then depressurize the metal tank. Then unscrew a lid at the top, pour more nutrient solution in and screw the lid back on. Then supply power back to the compressor again to re-pressurizer the metal tank.

Not sure exactly how much nutrient solution is needed in the reservoir (metal tank/accumulator) to last any amount of days, but I can think of a few possibilities that shouldn't cost that much. Like modifying a used co2 tank/canister, or modifying a clean small metal fuel cell (auxiliary gas tank that hasn't been used). If you could find a clean "unused and new" 5 gallon propane tank, then modifying it. New propane tanks full of propane only sell for $50, half that empty. You could even go to the extreme of having a welding shop weld together a square box with welded reinforced sides for under $100. A box the size of 1 cubic foot will hold over 7 gallons of nutrient solution.


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HH,
Bar is a measurement of pressure, 1 bar = 14.7psi. 16-bar is the safe working pressure of the accumulator.

The accumulator is precharged with air when its empty, a butyl bladder contains the nutes to keep them completely seperate from the air in the tank and the shell.

Nutes will attack unprotected steel and cause it to rust from the inside out, contaminating the nutes in the process. The rusting will eventually compromise the strength of the tank.


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Thanks hex,
So what you refer to as bar is actually, just a measure of the pressure the metal tank (referred to as the accumulator) can handle safely. OK, that works, but I will probably never refer to the measurement as bar. But rather to say simply using a container that can handle a particular PSI. Like the PVC tubing I use is not rated in BAR, it has a temp and PSI rating though.

I don't think any of the options I referred to was unprotected metal (with the possible exception of the welded tank (and that would be depending on the metal you chose to build it with). All the others are lined/made with a stainless steel that wont rust. If it would it wouldn't be safe to use for continued pressurized use (and decades of use), it wouldn't have passed the government inspection process.

"The accumulator is precharged with air when its empty, a butyl bladder contains the nutes to keep them completely seperate from the air in the tank and the shell."

This sounds unnecessary to me, and just a a possible point of failure. Bladder's eventually ware out. And if you were able to subject the nutrient solution to compressed air, that would only help keep dissolved oxygen levels of the water at maximum levels. The bladder will only keep that from happening. Also bladder or not, you would still need to depressurize the system before opening it to add more nutrient solution. I just don't see any benefit to using a batter in the metal tank?


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HH,
all accumulators have bladders just as all well storage tanks do.(at least that I've seen) It's just the way they're manufactured. Same with the precharge. They all come that way.
I think they work like this: you add water which compresses the air already inside the accumulator. Thus, you need a liquid pump that can handle the high pressure to fill the tank.
What you describe could probably be done by modifying a pressure cooker and adding a custom bladder, but you're getting into dangerous territory jerry rigging high pressure steel vessels.

Hex
I see the error in what I was describing above. I was seeing the misters in series. I seems they operate in a way more analogous to parallel.
I suppose I need to do a little more research into the volumetric flow of the mister heads.


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HH
The bladder is not under any strain as the air pressure on one side is in equilbrium with the water pressure on the other side. As water is pumped in under pressure the captive air in the tank is compressed into a smaller volume and the air pressure increases.

Grizz,
Nozzle selection is finding a balance between flowrate, mist coverage and droplet size range.

Its worth noting that standard reverse osmosis bladder tanks (steel type) are perfectly serviceable for aero use as long as you dont exceed 90psi. A 5gal r/o tank running 60psi-90psi will supply around 1.4gal of nutes. You could hook several tanks in parallel to increase the capacity if necessary.


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hex
If your using a water pump, that sounds like an expensive pump to be able to pump out 200+ psi. I have found small pressure washers that could supply that much pressure, even more, though they run $100+. The small air compressor for inflating tires runs about $20-$30. Couldn't you just pump air into the side of the bladder with the air pocket and get the same results?


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RE: tanks

P.S.
I'm still not sure I see a benefit to using a tank with a bladder, but I looked up some RO tanks online and they seem reasonably priced. Even brand new RO tanks start around $50, and if they require less modification, I'm thinking that would be the way to go. I can probably find used ones that never had anything but water in them for around $10.


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That approach would likely stress the bladder too much. The compressed air in the tank supports the bladder "as" the water is being pumped in under pressure.
A $10 tank could be a bargain if its only been used for r/o at standard hosehold pressures of 7psi-40psi
I paid the equivalent of $250 for my pump brand new but it was on special offer at the time (normal price $445) it can do 800+ psi. It will last forever with a 230psi tank so a 100psi max r/o tank will pose no threat at all :)

I do use an electrically powered diaphragm pump with a 6.6gal accumulator for the large high pressure setup. It worked out more cost effective than buying a large tank with enough capacity to provide a days worth of running from a single charge. The pump runs once every 5-10 hours depending on the mist timing.


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"The pump runs once every 5-10 hours depending on the mist timing."

Wow!!!!!!!!!!!!!!!!!you really save alot of water. How much water do you use a day given the size of the garden?About?


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Hex
Our household pressure is regulated at 60 psi. I know this for sure because I have replaced the regulator myself. The city water company has told me this, as well as at Home Depot the ones they sell are for this area, and are pre-set to 60 psi.

Not really sure how it would stress the battler anymore than it would be anyway. As you said the pressure would be equal on both sides. Filling one side with water (and not under pressure), thus pressurizing the air pocket side at the same time. That should net the same results as pushing pressurized water in one side to increasing volume, and thus compressing the air on the other.

But I still think it would be simpler and cheaper to not use a battler at all. Compressed air filling the top of a tank would have the same result (as far as I can tell), pushing down on the water (providing water pressure). Just as with a battler, the amount of compressed air (in the air pocket) will affect how fast water pressure drops.

I know you use a cycle timer to control water flow to the mister heads, and that they mist for a very short time, but quite often. But how much water/nutrient solution is used to mist the roots each day? That could be a big factor in the size of the tank needed, and could be a good reason for using a high pressure water pump instead of manually filling the tank.


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MG
It depends on the plant species,size and environmental conditions, but somewhere between 0.01gal and 0.04gal per gallon of chamber volume per day.

HH
The pressure regulators i use are adjustable from 0-90psi,
http://www.vip-ltd.co.uk/catalogue/datasheets/28_0075.pdf

I guess you`ll have to give the air-over-water idea a go. Remember to leave enough initial air space to match the flowrate or the pressure will drop out during the first misting.
The interesting part will be figuring how much water is left in the tank,(a pressure gauge isnt much good) the last thing you want is for it to run dry at 2am.
If the compressor doesnt have a receiver it will fire up throughout the night to maintain the tank pressure :)


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Hex
I know they make other pressure regulators I was referring to the statement. "standard hosehold pressures of 7psi-40psi " Our RO system works at 60 psi. I have no idea what the tanks are rated at, but I'm sure that government safety regulations would require it to be well above the max possible pressure when a water pressure regulator fails (depending on variables they only last 3-7 years). I know our city water pressure can reach over 100 psi. so I would guess to satisfy regulations those RO tanks would need to be able to withstand at least 150 psi.

Remember to leave enough initial air space to match the flowrate or the pressure will drop out during the first misting.

Absolutely, that's one of the reasons I was asking how much water your systems went through per day. Although the air pressure can easily be kept above a certain minimum psi automatically. If set at say 100 psi, as soon as it doped below that, the air compressor would kick on again, and bring up the psi to the set level again. The larger the air pocket, the less frequently the compressor would need to kick on.

But the main reason I asked was because I don't want the tank run run dry. As an example if the system went through say 2 gallons of water each day, that's 14 gallons per week. To be on the safe side I would want a tank with a water volume of about 20 gallons to be sure it wouldn't be pushing out air at the end of the week. If it went through 1 gallon per day, then a 10 gallon water volume tank would suffice for the week etc. etc.. what ever size the water volume, I would want about 1/3 of the total tank volume to be dedicated to the air pocket, in order to keep the compressor from kicking on to often.


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You`ll struggle to find a pressure switch with a zero differential, 10-15psi would be about the minimum. The best option is to use a compressor with a receiver and set the air regulator for the desired pressure. The receiver maintains the tank pressure automatically and the compressor only runs occasionally to bring the receiver back up to pressure.

Without a receiver, the compressor will probably run at every misting which brings up another important question: Can a small compressor startup against a 90psi load?
Most shop compressors are equipped with an unloader valve which dumps all the pressure when the motor stops, so the compressor can start with no load.

A bladder tank and a water pump is looking easier by the minute :)


 o
RE: DIY Aero

Curiousity got the better of me, calculator time.

A 100L tank, 75L filled with nutes leaving 25L of air at 0psi.
Total air needed to bring the tank upto 100psi = 6.247 cubic feet or 46.71 us gal.
For each 1L (0.2642 us gal) of nutes you take out of the tank the air pressure will drops by around 4psi. To bring the tank pressure back upto 100psi for each 1L nutes removed requires about 1.85gal of air.
So 1gal of nutes out = 7gal or 0.936 cubic feet of air to maintain the pressure.
A small shop compressor (2hp) with a 25L receiver and pressure switch setting of 100psi-120psi will give you about 1.2 cubic feet before the compressor fires up.

That equates to around 1.28gal of nutes delivered at 100psi per compressor run.

It should give you some idea of where to start. i need a coffee lol


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