Portable Hydroponic Tower

[Mosaic]

Hello All:

I am an engineer, so I need lot's of agric. advice!.

I've designed and built a 6' tall system of 4" DWV PVC tubes. The current design has 5 vertical tubes sitting on a 'reservoir' of elbows and tees with another supporting set of elbows and tees at the top for a rigid system.

It occupies about 2' by 2' and I have 12 useful growholes (2") in each tube.

At the base of each tube is a gravel bed 'filter' and the tubes have various mixes of sharpsand and promix. Excess nutrient drains back into the lower reservoir. The purpose of this model was to figure out a good 'soil' mix. The plants are fed from the bottom reservoir via a 1/2" pipe network in each of the 4" tubes. A pump lifts the nutrients up the centre 1/2" pipe and distributes from the top to the 4 corner 1/2" down pipes.
The 1/2" pipes are slotted to provide nutrient flow at all levels.

I built a microcontroller system to run the pump on 8 hr intervals with adjustable durations. The controller monitors reservoir liquid level, pump operation, energy efficiency, and battery condition. The system is solar operated using a 5watt panel and a 5AH 12VDC sealed Lead acid cell.

I have a 7 tube and 9 tube system designed with dual reservoirs (same 2' x 2' footprint) BUT I want to establish plant growth parameters, eg nutrient mix & cycle and media selection.

I used sharp sand & promix inert media in various percentages. Nutrient was simply Nutrex mixed 1 Tblespoon per gallon. I used chives as a test plant. After planting mature chives, they grew well for the first 2 weeks and then started to slow. After cutback (4 weeks) last week only about 10% is growing well ...all near the tops of the DWV tubes, lower plants are struggling. I pulled a couple and the roots seems soggy/melting.

We've had a lot of rainfall lately and water does get into the system thru the grow holes.

I am looking at the following possibilities:
1) Too much soaking causing root decay. Possible rainfall soaking is keeping everything damp, little evaporation happens in this system.
2) Nutrient mix lacks trace elements and is insufficient for hydroponics in inert media as used.
3) High sharp sand ratios are damaging the roots physically as soil compression and settling occurs.
4) Weak oxygen supply to roots.


Possible solutions
1) Add 50% 1/2" or 3/4" washed gravel to the 'soil' mix to reduce water holding.

2) Consider another nutrient mix.

3) Wad the plant root with some promix or potting soil before planting.

4) Introduce an aquarium airstone/pump to aerate the nutrient on a timed basis before pump cycle.


What do u guys think?

[rainbowgardener]

I don't know anything about hydroponics and hopefully someone will come by that does. But what I think is that it sounds like a whole lot of trouble to go to, to grow something you could just stick in the ground! But I'm sure it is fun to play with.

[brogz]

I would use a soiless mix like perlite and vermiculite. With 3 to 5 parts perlite and 1 part vermiculite. The vermiculite will hold the water but not too much to keep the mix soggy. I would use some large or coarse perlite and vermiculite.

Also a airstone is a must in hydroponic systems. If you have a 20 gallon or so reservoir I would put 2 airstones in there.

Hope that helps.

[fintuckyfarms]

In my strawberry towers I only use perlite and so far that is working well. As it gets warmer out, I have adjusted the feeding durating to longer lengths and more frequently. I started at 3 minutes every hour and now am up to 15 minutes ever hour. I would also add a air stone that is on 24/7. Hope this helps....