Wow, lots of progress. Looking good. You might want to paint that wood, or somehow cover it. I always seem to get a bit of mold if I leave uncovered wood too close to the surface. Cut the leaky part out and start over. You will be annoyed forever if you don't. Use lots of silicone around the fittings when assembling. Regarding the water tank: Obviously I have the same issue on recirculation, since I have the same tank. My current leaning is to just put a small powerhead on the end of a PVC pipe, that extends down through the lid, so it is near the bottom. I need to mount a small float switch there as well. The other crazy idea was an air stone in a short pipe, attached to a float. The air would both aerate, and act like a weak pump (think old under-gravel-filter). Since it floats, it goes up and down with the level, so no need for a powerful air pump.