First encounter with DE Filter

[Mike_in_NJ]

7 cups of DE, as in seven 8-ounce measuring cups??? Way too little DE.

There should be a label on the filter saying how much DE to use. A 36 ft2 DE filter usually should take about 3.6 pounds of DE. An empty 'pound' coffee can will hold about 1/2 pound of DE powder, so you'd need 7 cans full of DE to get your 3.5 pounds of DE (close enough to 3.6 pounds).

As to the pressure, maybe your pressure gauge is NG and needs to be replaced. Or you don't have to valving set properly and you are starving the pump of water and hence have a very low pressure. Or you have a suction-side air leak and hence have low pressure. It could be many things, or maybe that is just the pressure that your clean filter runs at.

[chemicalbalance]

1. Dont guess how much DE to use. The DE box will tell you exactly how much to use. Just put that amount in a bucket. Add some water to make a slurry and dump it in the skimmer. The slurry will coat the filter. Once you do this and let it run awhile, you can shut the pump off, remove the filter cover and visually observe that the DE is coating the filter like white mud. There shouldnt be any screen visible. Its really pretty simply and fail proof. You wont screw it up.

2. I do not rely on the pressure guage on the filter to tell me when to change the DE. I have found that my filter can be totally clogged and the pressure guage doesnt move at all. (And I am an oilfield engineer and I replaced my cheap pressure guage with a high quaility industrial brass one -- its not the guage.) I have found that when my filter is new, the return line to the pool is very strong -- like a jacuzzi jet and my vacuum works great. When my vacuum doesnt pick up or the kids complain that the return jet in the pool is weak, I know its time to change the DE. I have found that changing the DE every month works very well. Some people say that you can let it go almost a season, but I like strong filtration. Its your preference.