The grow beds are your biological filter - catching solids to be break down by worms, bacteria.
The pipes you referring to is probably Nutrient Thin Film
The pipes allow you to increase your growth space vertical (pending type of crop you intend to grow).
the 12" is just a recommendation - as it allows for good root growth and aeration.
Thank you for your response.
Do you know of a chart that shows which plants grow best in a PVC pipe vs floating vs 12" growbed?
Unfortunately not Woody
- best is to do a few experiments with plants and see what grow.
Plants with a shallow root system... lettuce and strawberries are good for that type of grow.
My first hydroponics experiment was with a 4" pvc pipe. I strapped it the railing of the porch, put a rubbermaid container under one end for a sump, and had a pump direct the nutrient to the other end of the pipe. I used 2" net cups and grew fantastic, huge, tender, delicious romaine lettuce and decent Brite-lights swiss chard. This was a continuous flow setup. The downside was that the roots followed the flow of water downstream and tangled together. However, it just meant I had to use up the harvest (but not all at once) before I could replant.
What 4" pipes are really good for is growing out seedlings, or as a temp holding space for seedlings. Tomatoes love it (while they are young - they have to eventually be planted in media). I can put 4 grow pipes on a "grow table" (2x8') on my porch, plumb them together and use one sump and pump. I put all my 2" net pots (I space them close together) in these, about a 120 plants, to acclimate them and hold them until I am ready to put them into the main aquaponics system. I use hydroponics nutrients to start them, since in early spring the fish ponds aren't fully activated.
4" pipes could probably be used in a vertical NFT system for small plants. Again, the difficulty is keeping the roots from tangling among the plants. I have had tomato roots grow over 3 feet - they will follow the flow of the water.
Thin walled pipe can be used, but has to be supported along its length - 4 supports aren't enough; the pipe will bend. Also must be painted or draped to block light and insulated.
I just picked up a couple of 4" drain pipes for about $6 each for my first NFT setup.. The\y are white thin walled but have a black inner wall so painting won't be necessary. They are rigid enough I think I shouldn't need more than 3 supports. Got them at Menard's. Plan on using them for cabbage and strawberries and might move them to the basement for winter growing.