We are currently building a small in-ground concrete block pool (2300 gallons). About 2.5 feet are underground and the other 1.5 feet is above the ground. The wall fittings for filter/heater, we were going to drill out a hole through the block and run the fitting through the block. Then we can attach the filter hose on the portion of pipe on the outside. We were planning to use a boat hull drain fitting (see picture below), these are almost long enough to extend all the way out the other side of the block without adding another pipe to extend it. The blocks will be filled with concrete so we want to get them installed before that. Anyone that built one of these pools, what did you use and how did it work out?