Adding DE to Sand filter... Minimal PSI increase

[Sdhb]

Hi all. I've added pool grade DE to my Hayward Sand filter via skimmer using instructions here to enhance filtering capability : Add DE to a Sand Filter

I started with a 1/4 cup, increasing to 2 cups and then finally to 3 cups which is more than is recommended.. I did so because I was not seeing much of a pressure rise. After 3 cups I saw barely a 0.5psi rise (from 15psi to 15.5psi). I had previously just backwashed before adding DE, so 15psi is my baseline.

Is it strange that pressure didn't rise 1-2 psi as expected? Pool appears clear, I don't believe DE passed through the return jets.

 

[PoolStored]

What RPM are you running on your pump?

At low RPM, you won't see the rise. You should run your pump on high RPM when adding DE, then when you get the pressure rise, you should turn the pump down. Will filter better at low RPM.

Always run high RPM when checking/testing PSI for clean and for dirty, when you are looking for the 25% pressure rise (to clean) or small pressure rise when adding DE.

 

[Sdhb]

What RPM are you running on your pump?

At low RPM, you won't see the rise. You should run your pump on high RPM when adding DE, then when you get the pressure rise, you should turn the pump down. Will filter better at low RPM.

Always run high RPM when checking/testing PSI for clean and for dirty, when you are looking for the 25% pressure rise (to clean) or small pressure rise when adding DE.

Yes, I was running at high (3450rpm) when adding. As it turns out I just checked this morning and pressure is now at 18psi from 15psi baseline. So it seems that there was either a significant delay in seeing the DE pressure rise.. Or perhaps it worked and I've caught a bunch more smaller debris in the filter overnight?

 

[PoolStored]

Or perhaps it worked and I've caught a bunch more smaller debris in the filter overnight?

Likely.