Here is the situation.
My chemicals are perfect, pool is crystal clean. The psi on the filter would read 17, but rise quickly to 25, within a day. I back washed the filter and it would drop back to 17. I was not aware that you had to add de each time you back washed. The previous home owner told me he added 4 coffee cans of DE filter aid, and that was sufficient. Troubled by the rise in pressure, I took apart the grids on the filter, and cleaned them. I discovered the grids were 30" high and 20" wide. I did some research and found the filter by those measurements should be a 60ft2 filter. Based on that I added 7 1/2 pounds of DE, not the 4 scoops the previous owner had done. When I say I added 7 1/2 pounds..the box stated 3 cups equals a half pound. So I added just over 42 cups (6 cups equal 1 pound). This was way more than the previous home owner did...with this calculation, he added about 2 pounds.
So here is my issue, and sorry for the long story. Every thing appears fine, but the PSI reads 23. The next day 24, and today 25. Did I add to much DE? Is the filter measurements correct on my part (60ft2). Why is the pressure rising?
Pool : 20,000 gallons
Pump: Hayward super II pump 1 1/2 hp
Filter: Hayward DE (60ft2 ???)
2 returns (jets) 1 collection skimmer( water just slightly above middle of skimmer)
Gunite pool with vinyl liner, 8ft deep end, 3ft shallow.