Newbie with the goal of designing and building a 40-60gal fish tank with either gravel or sand base for a healthy number of cichlids to enjoy watching them making homes and breeding. An air lift pump inside the tank will create flow and stir up solids, maybe incorporate a mechanical filter within. The tank will be drilled at the top to set a water level... water will overflow to a grow bed, after dropping through a mechanical sponge or filter floss. The bed will drain into a sump where a pump will bring the (clean) water up to a series of PVC tubes for NFT growing, probably lettuce. The water will zig zag through the pipes, or I will build them in parallel and collect them back above the fish tank, into which will spray return water.
Not sure about the bed... probably will go with the expanded clay stuff, but am intrigued by the sand as well. That said, I really don't want sand ending up in the sump and the pump, so I think the clay is a good idea.
I've got a kitchen cabinet next to a mini kitchen, so can create a safety overflow drain for the aquarium as well as support the grow bed by a window, which I will supplement with grow lights on a timer. The cabinet counter can support the grow bed and aquarium, and there is an empty space below where I can place the sump. The PVC NFT beds can span above the grow bed and the fish tank.
Advantages are mechanical and biological filters before the sump, which can be in the dark, minimizing solids and algae growth. Only one pump for water movement means the system will remain "balanced" and I won't have to worry about water building up somewhere. If the electricity runs out, no overflows occur. Excess water ends up in the sump. The water returning to the fish tank will be cleaned mechanically and twice biologically, and well aerated. The grow bed will be 1' above counter height, so a nice height at which to harvest. The PVC grow tubes will be higher, admittedly, but do take advantage of available natural light.
Questions: should I bother with a Bell siphon, or just plumb a standpipe at a certain height? What plants to grow in the bed? I've got the idea to grow strawberries for my daughter, perhaps some chives and oregano. How often should I be able to turn over the fish tank? 6-8 times per hour is the goal for aquariums, is that the goal here? I anticipate need to lift the water 5 feet or thereabouts, so what pump might be well suited? Any other ideas? Foreseeable problems?