Going to build a HOB refugium, haven't decided if I can make it work hanging on my sump or not. Anyway, I'm going to use a breeder box and grow light. I'm just trying to figure out how to get water to flow into it in order for it to flow back out. I was thinking an airline with small air pump that would hopefully draw water in as the air bubbles move up. I suppose a very small pump could work as well but I don't want an intense current. Any ideas would be much appreciated!