Several question:
1. For those of you using the cube type PVC design, is the tubing completely closed?
Not in less you want that option as some suppliers supply a piece to fit in the fittings to block out water. Personally I want the frame to fill with water which is why I drill some holes into it. My flotation consists of Clorox jugs, detergent jubs, or anything similar (rinse them well before using) tied to the sides of the cage except where the cage butts up against the pier.
I guess the air trapped inside will help with flotation, but it won't help so much that the whole thing floats on top, will it?
No. With an air filled frame, the cage will want to not sit properly in the water. I prefer using the jugs as it allows me to set it at whatever depth I want it at. I prefer up to a foot of the cage out of the water to keep the cover from drooping in the water as I use cages up to 7 feet in diameter.
2. Is shade a necessary addition?
Yes. Fish stress out in direct sunlight. They need a shaded area to go under in the cage. I use plastic tarp fastened to the top of my cage about 1/3 the width of the surface area (varies and not written in stone.)
3. The area that I would put my fish cage in is currently not aerated. Could one of these cheap, little, floating, solar powered aerator, fountain things be tethered to it to add some circulation?
Possibly. I don't always use any aeration especially if the cage is over deep water with good wind flow. If I do use aeration it's a diffuser near the cage. Never permanently place a diffuser directly under a cage. The fish don't like it and become stressed by it. However I have been know to pull the cage temporarily over a diffuser next to the pier to get any algae that is on the bottom to float up and be removed with a dip net.
I'm moving fish from one cage to another today if it stops raining. I will take some pictures and post them if you're interested.
