Journey to Hydroponics Part 2, Hydroponics Systems

 

September 5, 2019

Photos courtesy of Mike Heath.

Above left: Hydroponic towers designed by Mike Heath.

After last week's article I think you may have gotten he impression that I'm sold on hydroponics. If so, you would be correct. But, the question that remains is, "what kind of hydroponic system will work best?" There really isn't a simple answer. There are many types of systems and they all have a place.

When I started this journey I didn't have a clue what I was looking for. The Internet was my vehicle to answers and it actually opened up more questions than it gave answers. I was looking to maximize production while minimizing space. Most everything I found was either very small hobby systems or very large commercial operations. I wanted to be somewhere in the middle. I finally settled on testing two different types of systems.

There are basically five types of systems: flood floor; drip; ebb & flow, nutrient film, and floating. The flood floor system is exactly what it sounds like and it was taken off the list right away. Simply put, the entire floor is flooded and the plants grow right on the floor. It takes a special, porous concrete and recapture system under the floor. That was much, much more than I wanted to put into a system. I needed something more economical and simpler to build.


The drip system drips the nutrient mix over the roots so that they pretty much remain in the nutrient mix constantly yet they are not completely submerged. The nutrient mix can be either recovered or disposed of. Actually, all of the other methods can be used with a recovery tank or disposed of. When I saw the cost of the nutrients, I knew immediately that I wouldn't be throwing it out. Whatever I was going to use would have to have a recovery tank so the nutrient mix would constantly recycle through the system. The ebb & flow system uses a timer to fill the system then drain it on a regular cycle. The system will fill so that the roots are submerged in the nutrient mix then the system drains the mix out leaving the roots exposed to the air. As long as the roots don't dry out this is good. The plant takes in necessary oxygen through the roots. The nutrient film system sprays a nutrient mix over the roots constantly then the mix drains back down to the tank to cycle back into the sprayer. The floating system uses Styrofoam floats for the plants to be placed in. The floats rest on top of a "pond" of nutrient mix. For this system, the mix has to be aerated since the roots will be constantly submerged in the nutrient mix without access to oxygen unless it is somehow introduced into the mix itself.


The first system I built is a mutant system. It combines the nutrient film and the ebb & flow methods into a tower. The mix is pumped up into the top of the towers where it flows down across the roots of the plants. The system is on a timer so it pumps the mix across the roots for 45 minutes then stops for 15 minutes for the system to drain. The towers are set at about a 15 degree angle so the water runs down the front of the tubes to flow across the roots and provide the nutrient film. The other system is a traditional ebb & flow system. That's the one growing the tomatoes I talked about last week. It cycles for 30 minutes on and 30 minutes off.

The tower setup allows me to grow 299 plants on only 42 square feet of floor space, including the vertical lights. In the garden that number of plants would take at least 300 square feet. I used 2 inch PVC pipe with wyes set so that there is 8 inches between plants, both vertically and horizontally. Yes, I'm trying to pack the plants in. I used drain cleanouts on each end. The cleanouts are held in by compression. That way I can remove them for easy cleaning. I just use a chimney brush with fiberglass rods to clean the bottom drain. Each of the towers is set into the bottom drain on a tee, but without glue. That way I can take the towers out if necessary for cleaning. This system has been my greatest challenge of the year, so far. I started out with a 585 gallon per hour submersible pump pushing the nutrient mix through quarter inch drip lines. Everything seemed to be working fine until the drip lines started plugging up with the nutrient mix. The mix I use has the nutrients in suspension instead of solution. That means that there are minute particles of fertilizer floating in the liquid. What I hadn't considered is that the quarter inch lines are measured as an outside diameter. The couplings that attached the small lines to the half inch main line are slightly under an eighth of an inch inside diameter. The solids in the nutrient mix were plugging the system.

Me, being the smart guy that I thought I was, made the snap decision to just use a larger drip line. That way the nutrient wouldn't be able to plug the line. So I put on a three eights inch drip line. I was right. It didn't plug up. Unfortunately, there wasn't enough pressure to operate more than three lines. I have 23. So the plants weren't getting liquid across the roots and started drying out. Say that right, "DYING". Easy answer, smart guy. Get a bigger pump. I got a 3,100 gallon per hour pump. Yep, that did the trick. All of the line ran...all over the floor. Too much pump, too little drain. Okay, dumb guy. 1,500 gallon per hour pump next. It wouldn't run all the lines, Only six. More dead plants. Now I'm scratching my head. I ended up necking down the drip lines to a quarter inch, inside diameter, and putting the big pump back on the system. I also increased the size of the drain from three quarter inch to one inch. Finally, I have a system that's working. A lot of wasted nutrient mix and time, but I finally got it.

The ebb & flow system caused some problems to, in the beginning, but nothing like the big system. It kept overflowing and I couldn't figure out why. It was going through about 18 gallons of nutrient mix a day. Then came the light bulb experience. The last day I had problems with it, I opened the lid to find roots hanging out of the drain line. Simple answer. The tomatoes had roots over two feet long and they were plugging up the drain. Cut the roots off , clean the drain and, "VIOLA", no more problems. I did use a 4 four inch PVC pipe for the bottom drain and I don't believe that is enough. If I were to do this type of system again, I would use at least a six inch pipe.

Like one of my greatly respected Master Gardeners, Kathy Shreve likes to quote, "My green thumb came only as a result of the mistakes I made while learning to see things from the plant's point of view."  ~H. Fred Dale. But sometimes learning can make me feel so foolish. Don't be afraid to make mistakes. We all learn that way. As always, if you have any questions, ask a Master Gardener. It's what we do. More hydroponics next week.

 

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