I have a question about my system. I'm having a couple of leaking issues and feel now is the time to replace the filter from DE to sand. Anyhow, I've noticed that I have two inch piping from the spa and pool to the pump (1.5hp motor). Two inch piping out of the pump to a two way valve. One side of the valve reduces down to 1 1/2" through a filter to the pool sweeper and I believe it is 2" piping to the DE filter. Out of the filter is 1 1/2" piping to the heater and then through a two-way valve to the spa and pool, all of which is 1 1/2" piping. My question is why go from 2" to 1 1/2" piping? Is it because of the pool sweeper line? I'm thinking of changing to a sand filter with a 6-way valve and was wondering if I should go with the 1 1/2" valve or do I need to use the 2"? Also, my current DE filter is 48 sqft., is a 30" (about 500lb sand, hayward S310S) necessary or can I go with a 24" (about 300lb sand, hayward, S224S?).