Rick,

You need surface area/filtration for the bacteria to break down the ammonia. If you are not using media in your grow beds, you will need some sort of filter. There are many options, but i have no experience with filters and wouldnt know what to recommend.

Doing some media and some raft grow beds is a fine option and works well. However, your fish capacity is going to be based on how much filtration you have. The water is just the blood in the vessels of the system. Either way, you want your fish tank -> filtration -> then Deep water culture (fancy name for rafts). If tilapia/fry make it into your rafts they will eat the roots and kill your plants.

You may be able to grow blue talapia to plate size in one season, but if not, you will need a plan for the wintering because they are mortal below water temperatures ~45 degrees. Blue and nile tilapia require a permit to poses in Texas. I am only able to work with mozambique which [theoretically] die at 55 degrees. I will post a system a day. the 5th system is my current one and you will see that i still use some tilapia but i have moved 95% to native fish that I can leave outdoors year round. Tilapia can filter feed and help control algae/moss, but I try to discourage people from using them in non tropical zones in outdoor aquaponics systems. There's really no good reason to not use native fish that you can stock year round.

Your bacteria are a living part of your aquaponics ecosystem. If you harvest, move or lose all of your fish during the winter the food for the bacteria will stop and all of the bacteria will die. The next summer you are going to have to start over from square 1 and re-"cycle" your system.

Another viable stocking plan that may interest you is to buy a little larger than fingerling tilapia, growing them for 6 summer months then do a full harvest and replacing them with trout for the 6 colder months. It is kind of a temperate crop rotation. You will need to start with larger fish which are a little more expensive but depending on your goals it may be a more desirable option for you.

I actually have some HSB in my current system. You will need to be more concerned about good water quality and high disolved oxygen but they should be able to take the temperature swings. They are a really neat fish. They seem very smart and they have never stop swimming (as far as i can tell). They swim in a pack/sphere that reminds me of the dog fights in movie top gun. They move as a unit around the tank. I cant seem to get them to eat pellets at the surface while i am standing there but if i walk across the patio and come back... all of the pellets are gone. These are new fingerlings that i have only had for a couple of week, so i have not gone a full year with 100 degree summers and some freezes to say for certain how they will do year round. However, i expect them to be fine.

If my blue gill ever spawn, I will move them back outside and move the fry to a grow out tank. Then i will bring 3 or 4 HSB into my 100g living room aquarium so I can watch and learn their behavior better.


brian








Last edited by bcotton; 05/28/13 08:18 AM.