If you run the pump constantly, you don't need to buy a timer. The reason most people run the pump constantly is because when the pump stopps minerals build up more and eventually can stop up the pump and drip emitters. I have been doing well with a modified NFT system (troughs with media and a small flow of nutrient at the top so somewhat similar to a drip system) where the pump runs all the time. I don't even have drip emitters at the ends so clogging there has not been a problem.

There are some threads where willard3 talks about pump flow rates but I don't really know how best to calculate. What I do know is that you always want to go large on the pump since you can add a bypass valve which will take up any excess and help airate your resivuar as well.

(this is me totally guessing,) but I might figure at least 1 or 2 GPH per plant site and remember to figure the rise from where the pump is to the height of the drippers. If the pump is to run 24/7 then you might be able to stay to the low side but if you are going to only drip for short periods a few times a day, you should probably have a pump that will deliver a larger amount of liquid in a short time. Good luck.

Tclynx
I have been studying hydroponics systems for the last couple of months and I have got to tell you that Willard3s system is what I am building now. The system that he has generously shared with us is simple, easy to construct and I believe is the best.
What he has accomplished is to increase the oxygen content of the nutrient and also use a smaller capacity pump that does not heat up the nutrient so much. Every watt of the pump is transferred to the nutrient at 3.4 BTU so that is something that must be carefully considered during those hot summer days. He uses an external air pump to enrich the oxygen in the nutrient and this also does not contribute to the temp of the nutrient. The bypass with nutrient taking a plunge into the sump farther enriches the solution. One other way that he adds oxygen is to leave the ends of the 6" pipes open (open 6"elbows) to promote more oxygen into the system.
Now compare Willars3Âs system to systems using ¼ horse power pumps to blast a stream into a level in the grow chamber and you can logically see that you are using much more power and heat to accomplish the same thing. Some of these larger pumps are externally mounted to avoid the heat transfer to the nutrient solution but they still use much more power to accomplish the same thing.
If you study and compare his system to what is out there then I do believe you will come to the same conclusion.
oldude

I have pumped from 0.25 gpm/plant site to 1 gpm/plant site and notice very little difference to the plants. I think the small pump runs at 40w, 115v.

Even the small pump doesn't use the full 40w because I am Waaaay below maximum head. Maximum head (pressure) causes the most heat....another advantage of low pressure-drop emitters.

I'm always shocked at what commercial hydro purveyors will sell for a pump. I think it is a problem with the salesmen who have only ever seen 1/2 hp end-suction pumps their grandfather had in his basement. I also think green buyers have the same problem and believe bigger is better.....'taint......

Good to know Willard3. I keep getting such great tidbits from you. I've been using small pond pumps (actually the larger of the small sizes you find at home improvement stores, still too small to run a good waterfall but plenty big enough for hydroponics.) Probably a little bigger than I need for my currently small system but I plan to expand in the future and I had it on hand from a pond project that really needed a much larger pump for the waterfall.

Hi in the post on building a new system Willard3's system was mentioned as being a good place to start. Is there a link around to see the design - either diagrams or photos. I want to set up a system(s) in a greenhouse.

Here is the diagram again:

Brilliant, thanks a lot. I'm in NZ so am looking forward to getting a system up this summer Will keep you posted. Do pumps get affected by the nutrient salts if they are submersible, and if so is it better to set up an external one?

Hey willard3. The system plans you have, with some minor adjustments, you think it can be turned into a aeroponic system? Possibly putting some 180 degree spray jets at each site. Then again, that may require a bit larger pump being that it's not a drip system. I found some pretty good external pumps that run either 12V or 115V. I hear these are excellent pumps. I'm not spamming here, I just thought I would pass on a little helpful info.
http://www.sprayingequipmentsupply.com/pumps/diaphragm-pump.html

The system plans ARE aeroponic.....plant roots are in the air all the time.

180 degree spray jets look cool but plug up all the time and make a huge maintenance problem.

{{gwi:301205}}
This is a top-drip hydro system i used to grow peppers with great success. I used lava rock with a 'mulch' of pea gravel. I don't remeber exactly what the GPM rating of the pump i was using was but i had to poke a hole in the feed tube to relieve the pressure. If in doubt get the bigger of the pumps you are considering becasue you can always make a big pump flow less but you cant make a little pump flow more. I used drip rings made of 1/4" airiline tubing with holes melted into it and ran my pump 15min on 15 min off during the day, and i think it ran 1 15 min cycle in the middle of the night but otherwise it ws off at night.
I had great success, the peppers grew better than any of the soil grown peppers i've tried, and i only changed the nutrient solution about every 3 weeks. (i did add plain water to account for evaporation and water used by the plants)

You must remember that just becasue that is the way I do it does not mean it is the only 'right' way to do it. There are hundreds of ways to set up this type of system. The pump size, container size, type of drip emmitters, timing, growing media, strength of nutrient solution and many other factors will all be variable depending on what you are trying to accomplish in your specific system.

i hope i answered your questions.

karpes wrote:
The system that he has generously shared with us is simple, easy to construct and I believe is the best.

What he has accomplished is to increase the oxygen content of the nutrient and also use a smaller capacity pump that does not heat up the nutrient so much.

I mean no disrespect to you, willard3, or his design, but I would like to comment on your above statements.

When you say a system is the 'best' what does that mean? is it the best for growing strawberries? is it the best for growing pine trees? is it the best for growing watermellons? how can one hydroponic system simply be 'the best'? Any experienced hydroponic system designer would agree that there is no 'best' overall system. You should look at what you want to grow, and how you want to grow it to decide what is best for your individual application. Personally, I think the system he describes on the diagram would be (relativly) expensive to build and horribly inefficient use of space becasue the growing chamber (root space) probably uses less than 1/3 of the total system footprint. Not to say that i dont think it would work, but the only thing that system is the 'best' at is spoon-feeding a single, basic hydroponic design to people too lazy to learn hydroponic theory and come up with their own ideas. I.M.H.O., the fact that there is a picture and a parts list so nothing new has to be learned to build one is not reason enough to call it the best.

Next point- Roots vs. Oxygen
In economics there is a term called Diminishing Marginal Utility. Basically it refers to the decline in additional utility from consumption of an additional unit of a good as more and more of the good is consumed. Take eating pancakes for example, one pancake is delicious, two is pretty good, by the third you might still be enjoying them, but somewhere around pancake 12 you'll be saying "i hate pancakes". The utility has diminshed to the point where even if someone gave you another pancake for free, you would not want to eat it. The same lesson hold true for plant roots and oxygen. they need some oxygen to survive, adding a little more than what soil can provide is part of what gives hydro the edge over soil growing, but eventually, the oxygen to the roots becomes the pancakes to you or I, they simply can not use anymore. there are quite literally thousands of hydroponic designs that do not use bubblers, falls, and open algea spawning windows to supersaturate the nutirents with air that have worked just fine for decades. Again, i do not mean to be disresectful to you but from the above statements, my guess is that you are just parroting back what some website said and that you really do not have a solid understanding of the root/oxygen relationship. There is a wealth of information both online and at the local library about cellular respiration. If you want to really understand WHY and HOW hydroponics works and not have to rely on the designs of others, this is a great thing to learn.

Finally, the pump-to-solution heat transfer difference between two similar pumps (say a 95GPH and a 120GPH) will be negligable. Unless this is the only system you ever want to use the pump for, buy bigger and you'll have a more versatile pump for future hydroponic designs.

my sarcasm and flippant tone make this sound like i'm trolling but really i just don't know how to get an idea across without using sarcastic humor (often lost in text based communicaton) or just calling it like i see it. Before anyone writes a heated response about what an arrogant douche i am please remember that what i wrote is just the musings of another anonymous internet user and nothing i type is worth getting upset about. i've been designing and building hydroponics for almost 9 years now and i guess partly i'm bitter becasue almost everything i learned when i started was through my own mistakes, i'm jelous that you n00bs get everything spelled out for you right from the start.

to the OP-
I think the important thing is to just build SOMETHING. a top drip design just requires 3 simple things. a growing chamber, a nutrient resivior, and a method of geting the nutrients back and forward from one to the other. the rest is just little details you'll learn as you go. good luck.

"spoon-feeding"...lol. Some do need spoon-feeding. We all need spoon-feeding some time or another. In my personal opinion, trying to use the least amount of space(this also depends on what your growing), a pump that generates low heat, and a light source that puts out the correct spectrum or Kelvin rating, and bla,bla,bla, etc...etc... If your looking to build your own system and want it to last along time, research the materials that are used to make these systems(can hold up to the nutrients) and buy them locally.
Spray jets can be found at Lowe's and Home Depot along with gardening stores. I like the fact that L.E.D. lights are now being used for growing indoors. I researched that about 100 watts of L.E.D.'s will grow numerous plants and the good thing about it, almost no heat.
For those people that need help with hydroponics, if you have a hydroponic store within driving distance, you could get some "spoon-feeding" there. There is a magazine out there that is good for hydroponic knowledge and for equipment purchasing, since I can't mention the name on this forum, call one of the hydroponic stores and ask for a magazine that is strictly about hydroponics. Hope my opinions can be of help.

snip
Unless this is the only system you ever want to use the pump for, buy bigger and you'll have a more versatile pump for future hydroponic designs.
snip

By this theory, you should buy a 1000 gpm pump at 100 psi?

All pumps will wear out and have to be replaced and it is a good idea to have an idea of range of gpm/plant so you don't buy a 5hp split-case pump.

willard3 said:
By this theory, you should buy a 1000 gpm pump at 100 psi?

I'm sure we are both fully aware that you are taking my comment out of context but I'll play along.

Yes. because you can add a pressure relief valve to a 5hp pump and make it run just a few GPH this year, and next year when you want to design a new system thats bigger (and you will), you can adjust the flow rate up to accomidate the larger system. there is almost no chance that you'll 'outgrow' your pump before it has exceded its natural life expectancy and needed to be replaced anyway.

OTOH-

You buy the absolute minimum pump size you can to support the system you have built this year, and next year if you decide you want to do something bigger you need to go buy a new pump.

(the following numbers are entirely made up to demonstrate a concept, actuall pump statistics will vary greatly from what is listed)

Say you are looking at 3 pumps for your first hydro system:
Pump #1 is $30 and runs 60GPH @ 1ft of head (3ft max head)
Pump #2 is $40 and runs 90GPH @ 1ft of head (4ft max head)
Pump #3 is $50 and runs 130GPH @ 1ft off head (5ft max head)

for this years system pump #1 will work so you buy it and save $20 over the largest of the 3 pumps you were looking at. It works great! The hydro-garden yeild is amazing and next year you decide to make a bigger system. That 50GPH pump won't support the new design so you throw it on a shelf in the garage and go buy pump #2 that will support your new system. now you've spent $70 on pumps and there is still a chance you'll up-size again. I'm saying if you buy pump #3 the first year you may spend $20 you didnt have to the first year but you'll save money if you continue with hydroponics becasue you don't have to keep buying new pumps every time you want to expand.

Yes, pumps will break eventually so you shouldn't buy a hydroponic pump with the intentions of passing it down to your grandchildren for use in their hydroponic gardens one day. But if you buy name brand pumps and clean them occasionally they can last for a while. I have pumps that i've been using for 5 years still going strong. If they do break, the rebuild kits are widely available and cost considerably less than total pump replacement.

I'm not trying to make a personal attack on your system designs or choice of pumps. All I'm trying to convey is that most people start with a small-ish hydro setup to get their feet wet, then move on to bigger/better designs as they gain knowledge and confidence. My advice to anyone just getting started in hydro is not to cheap-out on components to save a buck. If you stick with it, you'll spend twice as much replacing inferior equipment as you'd have spent just buying decent stuff to begin with.