I have a 21 foot AGP installed on a slope. The high side is 3 feet high and the low side runs next to a natural sale. The swale runs along back of yard down to corner of yard about 2 feet lower than pool 20 feet away. I can't tell if I should put in a NDS easy drain tile around the pool before backfiling with dirt. Conflicting advice but I don't think it's necessary since the ground slopes away from pool and should drain naturally. Live in northern Kentucky so mostly clay soul.