NScooknet
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Joined: Sat Mar 03, 2012 8:35 pm
Location: Kingston, Nova Scotia

Need help with building PVC hydroponic system!!

Hi all,

I'm totally new to hydroponics, and I am just in the process of building my 1st PVC 4" tubing hydroponic setup to try my hand at it.

I have read multiple webpages and ebooks, and watched several youtube videos about the construction and operation of such setups, but after all that i still have some questions about it.

The first question I have is about the actual water level inside the tube and what I am trying to achieve in terms of supplying water to the plants.

Apparently there is a different construction technique between 6" and 4" systems, the 6" system has sprayers inside, while the 4" type that I'm building simply has a tube or single sprayer in one end that flows to a drain in the opposite end.

That much I get, but what I don't yet understand is about how the water interfaces with the plant pot, and how long it is supposed to be exposed to water.

Some instructions I've read state that the overflow tube in the PVC tube should be at the height that allows the water in the tube to just touch the bottom of the pot, thus allowing the water to saturate the growing medium, while others show a small gap between the bottom of the pot, and the top of the water with the roots dangling into the water.

That makes sense, but only "if" you already have a plant with long roots to dangle in the water!

Do I need to start the plants in a different setup first and then transplant them into the PVC system once they have roots, or can I just start them right in the PVC system?

Also, the tube never stays full of water because after the pump shuts off, the water will backflow into the pump, and back into the reservoir below.

This brings me to my next question, at what interval and for how long should the pump flow water into the tube to fill it so the pots get saturated with water?

Should water always be in the tube touching the plant, or is it only supposed to fill the tube periodically to wet the pot and then have the level drop down again to nothing inside the tube?

I'm wondering if the cycle is having water fill the tube and then coming up to the bottom of the pot to saturate the grow medium with water then retreating again (and leave an empty tube), or if there should always be water in the tube touching the grow medium which is periodically replenished with fresh water and nutrients at whatever interval it is supposed to be.

Hope I'm making sense!

I appreciate your help and guidance, once I know the "point" and theory of operation to this setup, I can ensure it's proper design and operation and thus assure my plants will actually survive...lol.

Thanks!!
Chris

NScooknet
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Location: Kingston, Nova Scotia

Doesn't anyone here use home made PVC pipe systems??

FL Grower
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Location: SE Florida

It's much easier if you start your plants in a separate container then transplant them into your system. You want the tips of the roots long enough to reach the water.

The length of the water cycles depend on the plants you are growing. Mind you, I've seen set ups where the water runs constently (NFT) and it seems to do well.

The depth of the water, just like the water cycle length is something you will need to experiment as you go along. There are no hard and fast rules as homemade systems can vary quite a bit. Remeber that the roots keep on growing so eventually half the tube could be roots (again, depending on what you are growing)

The best advice I can give you is to built it and experiment with it.

vorkus
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Joined: Tue Mar 06, 2012 2:37 am

I think what you are referring to are different types of systems. It doesn't depend on pipe diameter. You can either build an sprayer system or a nutrient film system. If you go with sprayers you need one between every plant and one at either end. The advantage is that you can put your plants in the system before the roots extend all the way to the bottom of the tube. The system should run on an interval timer. Something like 1 minute on 5 minutes off or 5 minutes on 30 minutes off (depends).

If you go with the nutrient film then you don't need a sprayer at all, but the system should run all the time. It doesn't have to be fast. As the name implies just a thin film of water at the bottom but it should flow not sit.

I've never done a nutrient film system because of the root length thing. I have done a spray arrangement (actually sprinklers). I did it in 4 inch pipe. Six inch would be better for larger plants but the same thing applies. I grew tomatoes in 4 inch pipe just fine.

NScooknet
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Location: Kingston, Nova Scotia

Hi,

Thanks for the reply.

I don't have a timer yet, so what I'm wondering is what is the difference between a flow of water that the pots are suspended in vs a sprayer between every pot running continuously.

In both cases the pot is continually getting wet so why would it matter if it is on timer and is on and off for a sprayer type scenario??

I actually ordered a bunch of fittings, rockwool, tubing and other goodies from a hydroponics supplier, which included some small 360 degree Microjet sprayers that I can install one per between each plant.

If I left those running 24/7, would there be an issue, especially since I'm thinking about starting the plants right in the pots in rockwool?

Thanks!
Chris :)

vorkus
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The difference is oxygen. The plant roots need oxygen to thrive. It also prevents root rot. Roots can "drown" from lack of oxygen. Sprayers provide the most oxygen. Aeroponics is supposed to provide faster growth. I've never tested this myself. Some people do run their sprayer systems continously. Others suggest intervals. I have no idea which is better. It may just be an energy consumption thing.

Beware of rockwool. It has some issues. One is it is not Ph neutral. Google it, there are ways around that. The other down side is you don't want to let rockwool in contact with water all the time. It is very absorbant and will cause root rot. It would be better to suspend the rockwool block over the nutrient flow and let the roots dangle in the water. I wouldn't use rockwool with sprayers. Better to use hydroton.

NScooknet
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vorkus wrote:The difference is oxygen. The plant roots need oxygen to thrive. It also prevents root rot. Roots can "drown" from lack of oxygen. Sprayers provide the most oxygen. Aeroponics is supposed to provide faster growth. I've never tested this myself. Some people do run their sprayer systems continously. Others suggest intervals. I have no idea which is better. It may just be an energy consumption thing.

Beware of rockwool. It has some issues. One is it is not Ph neutral. Google it, there are ways around that. The other down side is you don't want to let rockwool in contact with water all the time. It is very absorbant and will cause root rot. It would be better to suspend the rockwool block over the nutrient flow and let the roots dangle in the water. I wouldn't use rockwool with sprayers. Better to use hydroton.

I've got rockwool coming in the mail, just little 1.5" cubes for starting seedlings, and I currently have a large bag of coconut fiber (coir) and several blocks of oasis, but alas, no hydroton.

It is expensive to ship, and nobody local seems to have it.

So, If I have an aquarium air pump pumping bubbles into the reservoir, the pump constantly circulating (until I can find or build a timer) and those micro jet sprayers between each 2 plants in the PVC piping, do you think that will be ok?

And now for the choice of mediums.....will the coconut fiber be ok as long as I soak it and change the water several times to leech out and excess salt that may be in the water??

:)

vorkus
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The little rockwool plugs should be fine. I've never used coco fiber. I read something about it sucking up potassium and leaching phosphors (or perhaps the reverse). It's a pretty popular medium, but I've never used it. Perhaps I will next time around.

Aquarium pump in the reservoir is the way to go. Don't skimp. Get a good sized one. You can never have too much oxygen in the water.

Yeah, I know what you mean about the shipping. I found a company in Ohio (I live in western Pa) that I could get it from UPS ground which wasn't too bad. Recently I found a local supplier. I've heard people using aquarium gravel. Never tried it. Personally, I've used river stone (used for landscaping) when doing hydro outdoors. It worked well. Good luck!

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fintuckyfarms
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Re: Need help with building PVC hydroponic system!!

NScooknet wrote: The first question I have is about the actual water level inside the tube and what I am trying to achieve in terms of supplying water to the plants.

In my system (which was outside) I left the water just touching the bottom of the net pots and hand watered and plants that were transfered where the roots did not yet touch the water.


That much I get, but what I don't yet understand is about how the water interfaces with the plant pot, and how long it is supposed to be exposed to water.

In my system that started out a NFT system, the water was always on. As the plants got bigger and started to block the pipes I changed it to a flood and drain system and ran it 15 minutes every hour till it got about 85 degrees out side, then I ran it 15 minutes every half hour.

Some instructions I've read state that the overflow tube in the PVC tube should be at the height that allows the water in the tube to just touch the bottom of the pot, thus allowing the water to saturate the growing medium, while others show a small gap between the bottom of the pot, and the top of the water with the roots dangling into the water.

I like the water to touch the pots incase of power failure so the water can wick up the medium and help keep the plants cool.

Do I need to start the plants in a different setup first and then transplant them into the PVC system once they have roots, or can I just start them right in the PVC system?

I have seen where people start their seeds in the pipe system and just run a drip system temperally till the roots reach the water. I just hand water a few times a day.

Also, the tube never stays full of water because after the pump shuts off, the water will backflow into the pump, and back into the reservoir below.

Just adjust your bulk head (the fitting that attaches to the line from the pump) to the top of the pipe. This makes it so the water does not go back to the pump and it also aerates the water a little bit more. You can adjust how much water stays in the tube by adjusting (twisting) the exit end cap up or down.

This brings me to my next question, at what interval and for how long should the pump flow water into the tube to fill it so the pots get saturated with water?

That completly depends on they type of system you are planning (NFT, flood and drain, etc) and what you are growing and where you are growing. Also you have to take into account you environment in regards to lighting and temprature and if you are in a area prone to power failures.
I'm wondering if the cycle is having water fill the tube and then coming up to the bottom of the pot to saturate the grow medium with water then retreating again (and leave an empty tube), or if there should always be water in the tube touching the grow medium which is periodically replenished with fresh water and nutrients at whatever interval it is supposed to be.

Hope I'm making sense!

I appreciate your help and guidance, once I know the "point" and theory of operation to this setup, I can ensure it's proper design and operation and thus assure my plants will actually survive...lol.

Thanks!!
Chris

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