Stumbled across this forum & thread as I got a new Spec V for my african dwarf frogs. They were a gift - came in one of those little tiny plastic cubes. They needed a new home! Got them finally set up in the Fluval and they are so happy. But then today I saw one of them trying to squeeze through the lower opening to the filter side! Ack!
So found the suggestion about the electrical tape - BRILLIANT. Never would have thought it would stick when wet but it did! I only covered about 3/4 of it just in case the water level ever drops before I notice it. More than enough coverage to prevent the little fellas from entering the black hole to death.
Then I saw the suggestion to reduce flow by putting nylon over the black return valve. BRILLIANT! Found an old pair of knee-highs and cut off the thicker top part, rubber banded it across the valve, and boom - about 1/4 of the flow that was coming out. (though I kind of think they were having fun taking the Rapids Ride, as I was calling it)
NOW - I haven't found any good suggestions yet about how to cover the hole so my little sweeties can't end up dehydrated on my desk. They haven't tried to jump out yet, but I plan to give them floating plants at the top, which would give them the perfect springboard if they ever thought the grass could be greener elsewhere. I don't want to restrict the light. If I put a solid piece of plexiglass over the opening, would that adversely affect the tank? Ideally I'd like a clear plastic piece with slots, but I have no idea where to find such a thing. I wrote to Fluval, and they basically replied "nope, we have nothing and have no suggestions for you."
Thanks for such a great thread!