I am going to be installing a new Hayward C4030 cartidge filter. Some questions. Since I need to be able to drain the pool, I will be adding a waste line/valve just before the filter inlet. Would I use a 2 or 3 way valve for this? Second question, I am thinking that I should put in a recirculate line to bypass the filter for those times that I want to shock the pool and keep live algae from entering the filter. Does this make sense? Is this usual for a cartridge filter system? If a good idea, can someone give me the basics on how to plumb this? Last question, if I want these 2 functions, would it be cleaner/simpler to just add a standard multiport valve and not use the backwash and rinse functions (I know this would destroy the filter). The inlet and outlets are the same as a DE filter so I could potentially use a DE multiport. Or, would adding the this valve add unwanted backpressure that would not help with system efficiency? Appreciate any advice you can give me.