I am a hydraulic engineer for many years but only recently venturing into consulting/design of commercial swimming pools/spa. I am doing a large hotel pool (180,000 gal) with complete gutter system around pool (380 ft perimeter. Want to use collection tank. Estimate filtration rate to be at least 320 GPM. I am not familiar with main drain float valve in collection tank (need a pointer to suitable product - 2x6" lines?). When piping gutter from far end to pump room was planning 2 lines into collection tank increasing from 2" to 6" on each side with inlet pipes from gutter every 10 ft. Guidance would be appreciated. Thanks