I know the return line should be looped but why can't the skimmer lines also be looped?
I plan on installing my own pool this summer and I really don't see the purpose of a main drain. 1. I can always pump the water out if I need to. 2. I will have two skimmers. 3. If I vacuum my pool regularly then I really shouldn't have a problem with sediment at the bottom.
The proposed pool is an inground "T" shaped 28,500 gallon poly pool. Pool is in northern Ohio