I have a 9 year old in-ground concrete pool with a 2 hp single speed pump (this pump came with the pool when I purchased the home). My pool has 8,000 gallons with an attached spa and spillover. The pump has started to make loud noises when running and I think it's time to look for a replacement pump. Any suggestions on what would be the correct size? I feel the 2 hp is too large for my size pool.