Can someone offer a solution to my problem, please. I have a 130 Tenecor marine tank. I just purchased 6 small chromis and have found that they are getting swept into the prefilter and consequently down into the sump. How can I make the prefilter holes smaller? I would think that there might be some type of material that can be put over part of the holes (which are really slits) that will cover them but let the water flow through.