Pipe size for inground pool
I'm in the process of contracting a pool that is 20x48 with an average depth of 5.75. The pool will include an 8 ft deep end and an 3.5 ft shallow. The shallow end will be 24 ft in length and the other half will be the deep end.
The contractor states using a 1.5 HP Hayward Super Pump, Hayward 240t filter and 1.5 inch pipe will be sufficient to keep the pool clean in a 10 - 12 hour turnover cycle.
My question is this. If a 1.5 inch PVC pipe can only take 42 GPM shouldn't the pool require a 2 inch pipe? They continually state that the pool will be fine with 1.5 inch pipe and state the following reasons for discouraging me away from 2 inch pipe.
1. more surface area in the pipe makes the pressure flow into the pool less, thus less pressure means less movement of water and more time for water to get back to the skimmers.
2. Any automatic cleaner you use will run slower and may stop and go and will need an upsize adapter to 2"
3. all inlets and outlets in the pool wall and floor are factory cut for 1 Â½ " so an extra $600 will be added to the price to up size these openings.
I want to ensure 1.5 inch pipe is ok to use for a 20x48 pool because from what i have read a 42 GPM flow rate is the maximum for this size pipe. Please help me. I'm not writing a contract until I get this issue resolved.