Are you using clear hoses or Black ones for the pumps? Clear hoses make water get in there and it does a coat of algae on them. I try and keep my water temps a lil down in my bucket as well as keep the ph adjusted as best as possible so I don't have to swap out the RES as often. I'm only running one DWC right now but plan to get a recirculating setup going soon. Love the set up man can't wait to see the end results.:thumbsup: