Hydroponics ideas

my shool is looking into starting a hydroponics project(basically growing food like letuce on top of a fish tank). This will be fairlly small maybe 100-200 gallon tank to start. we are probibly going to put it in a greenhouse. This is also in the northern US so it is cold I figer on using tilapia. I will of course do other research but if anyone has sujestions, this is still very much in the planning stage although we do have a small prototype with catfish. basically any sujestions on fish, equipment, types of plants to grow ect. thanks

 

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Why do you need fish?

 

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thier waste fertilizes the plants and when they are big enough you eat them

 

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Wouldn't it be cheaper just to buy fertilizer and use that directly? Even better would be to use worm castings, they eat food waste of all kinds. I think you are going to have problems caring for both fish and plants in the same tank. There will be maintainence issues, and you will have to transfer the fish every time.

 

I kept some guppies and a few other (neon tetras, or zebera as I recall, but they were for fresh water.) in a modest tank without feeding them or cleaning the tank for about a year. The tank got direct sunlight on one side and on three sides a green scum formed which I did scrape off with razor blade tool. It was their food. Also there were some almost invisible worms that lived in the accumulated dropping at bottom of the tank (they were about an inch thick/deep). The fish would stir it up and eat them. These worms were about 1 cm long and about 0.04cm fat. (25 to 1 aspect ratio) They "swam" by making a loop of the body at one end and propagating it to the other end. I could only see them if they were in bright sunlight as their bodies are transpairant.

One thing very important was the crayfish. He ate the dead fish. If no fish died for several weeks, I took mercy on him and dropped a tiny piece of ham into the tank. I was amazed how clean and clear the water remained. Most people way over feed their fish, the food rots and clouds the water. I never bought any fish food.

Tank was about 20 inches deep and tall and perhaps 36 inches wide. Top was about half covered and a few times (less than every other month) I did take a gallon or so out and replace it with stream water as I feared the build up of some toxins or salts. I think the worms must have come from that or the Chesapeac Bay. (I had a small sail boat there and ocasionally took some sea weed off the rudder and adapted it to fresh water for a month or so before sticking it in the sand of the bottom, which was at one end of the tank only) There were a few rocks from the same stream as the cray fish on the bottom also.

 

Basic Intro:
What is hydroponics?
Basically, growing plants without the use of a traditional dirt medium and using a nutrient rich water solution. Those mediums range from fiberglass to sand and from fired clay balls to nothing at all. Several branches of hyrdoponics include aeroponics (using air as the grow medium), aquaponics etc.

How do I get started?
Well, you can buy a kit - but its going to cost you... a lot. Or, you can improvise and create your own kit to suite your needs. My local hydroponic supplier's cheapest multiplant kit is $185, does 8 plants but is not very versatile and is very compact. It uses the ebb and flow method. They also offer a single pot (bucket) bubbler system for $50. We are going to combine these two systems into a more versatile and much cheaper system.

What are my options
There are many different methods. NFT (nutrient film technique - stream a thin layer of nutrient solution over the roots) is common among professional kits - a long with ebb and flow (temporary flood your root system and allow to drain). The most interesting method involves suspending your plants in mid-air and spraying the root system very frequently (aka aeroponics). Drip systems are also common and has its own advantages. There are MANY methods - all of which do not use dirt

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What method is used here?
By far the simplest and cheapest is a bubbler system. That is, keep your pots filled with your choice of medium just barely above your nutrient solution level -- then keep the solution well aerated. The popping of the air bubbles will keep your medium moist. Remember that more simple and more cheap does not mean less effective

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http://www.instructables.com/id/Hydroponics---at-Home-and-for-Beginners/

 

Thanks for some info, with the prototype we are using pots suspended in blue board with rock wool in the bottoms. This seems to work quite well so far. we have been feeding the fish fish food although once some algea get going we may not need to. unfortunately the people feeding the tank are a little overzelous and put in WAY to much food, one of the cat fish died, so we fed it to the crabs in our saltwater tank. I would prefer not to use rock wool in our big tank and was wondering if we could use natural sponge. The clay balls also sound interesting. Again this is still in planning, I'm open to more sujestions.