Adding DE to Sand Filter

[dino1956]

I would like to try Adding DE to my Sand Filter.
I read the Instructions in Pool School.
But there is a line in there, I don't quite understand.
"The very first time you do this, you should keep an eye on the filter pressure for the next 24 hours or so. The improved filtering may quickly catch a lot of very fine particles and send the filter pressure up rapidly."
So how high does it send the PSI up? Am I suppose to know what a dangerous level of raising it should be? And does the Pressure go down afterward?
Thanks in advance.

 

[zea3]

Keep an eye on the gauge, it should have a red line area to show when pressure is too high. Most pools will see reduced return flow way before they reach that point. So if your filter normally runs about 10 psi clean you will probably see significantly reduced return flow around 20-25 psi. When you see reduced return flow back wash the filter and add more DE.

 

[JasonLion]

To put it another way: adding DE helps the filter catch more debris. As the filter catches debris the filter pressure goes up. When the filter pressure goes up by about 25% from the clean filter pressure you should backwash/clean the filter. At that point the pressure will go back down because you have removed the debris from the filter. You then add more DE and repeat.

 

[dino1956]

My Pressure is 17 when Clean.
So this is not just a one time deal.
Do it 3 or 4 times until you get it microscopically clean.
I'm joking about the microscopic line.
Thanks.

 

[JasonLion]

Correct