Hi all! I just purchased an EC50 D.E. filtering system with powerflow matrix pump, and I had a question: Because I have a large buildup of sediment and algae, is it possible to vacuum to waste with this model of filter? Do I need a shutoff valve on the return line to force the water out the drain port? Will doing this damage the flex-tubes? Any information regarding this subject would be greatly appreciated.

I have a large doughboy oval pool (42'x20'), about 22,000 gallons. I just opened it and shocked it today on the 20th.

Thanks!