I am building a Refugium for my 75g tank. It will be a 20g. I was going to copy SKAustin's design exactly but I am a little worried about some sand and the debris from the fuge section getting into the return pump. Would it be a bad idea to add a piece of sponge into the overflow from the refugium section to the return section? This would prevent any particles form getting into pump, but would this also prevent micro organisms? Any other tips would be greatly appreciated. By the way I think that I will be using a Rio 2100 pump. I will T off the return line, put my UV sterilizer and then put in back into the inlet section.