Hi all, Thanks so much for your advice on bottom drain sizing. My next consideration is some kind of mechanical pre filter befor the pump. I'd like to know if they are necesarry to install before the pump, or does todays pumps handle the types of sludge produced from the bottom drain just using a basket before the pump. If any of you are using some kind of pre filter, how happy are you with it? And what kind of maintenance or operational problems can I expect? Thanks