I decided it was finally time to make some better covers. I half-heartedly put plexiglass on top of my tanks, but over time they bow, and don't make a nice seal around the tanks. It's amazing how small a hole or gap the fish can rocket right through.
After looking at tips online I decided polycarbonate roofing panels were they way to go for now-- a relatively cheap material that's easy to work with. I still haven't broken the heat gun out to soften up the edges, or added the closure strips that seal up the holes at the ends, but they are already holding in much more humidity that I would have thought (the top shot is form overnight, the two 10's below I just finished).
Even though the fish could jump through holes less than half the size of the end of the corrigation, at least for the time being they can't go from tank to tank. (Which was the original problem I wanted the lids for...too many of my little friends keep trying to relocate. If they hit the carpet I lose a fish, which I hate, but if they jump into a tank of fry, I lose a lot of fish...which is more aggrivating.)
Hopefully by the end of the weekend I can get the closure strips up for added safety. I've also thought about pinning some of my emersed flowering plants into the spaces and letting them trail down the fronts of the tanks. So far I've finished 2 20's, 4 10's, and have 2 more 10's to go with this sheet.
I also added another diy mattenfilter, on a 30 gallon. They're ugly, but so far they're working great, and have been really helpful to push floating plants to the end of the tank, which makes them easy to collect/remove, as well as keeping them from blocking out the plants below...