28,000 in-ground pool. I have a Pentair 4000 with 8 grids. After adding one half an orange pitcher of DE the filter pressure will rise by 50% within a few hours to 30 on the gauge. Normal without DE is 18. I can run the filter for weeks without DE and the pressure does not increase much. Backwashing after DE is in the system drops the pressure back to the normal value of 18 but it quickly rises to 30 which is high. Will getting new grids correct the situation and allow backwashing to get rid of the DE to the street? The grids are probably 8-10 years old or older as I bought them used not knowing what I was doing back then. The attached photos show one grid that I have half sprayed off and the other is before any spraying. Thanks.
DE Filter Pressure Rises Fairly Quickly After Adding DE
- Thread starter DL777
- Start date
- Jul 21, 2013
- 52,474
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Welcome to TFP.
What you describe is usually an algae problem clogging the DE. You need to do a Overnight Chlorine Loss Test to confirm if you have algae in your water.
What test kit do you have?
You said you ran the grids without DE. Did you give the grids a good cleaning after doing that?
www.troublefreepool.com
What you describe is usually an algae problem clogging the DE. You need to do a Overnight Chlorine Loss Test to confirm if you have algae in your water.
What test kit do you have?
You said you ran the grids without DE. Did you give the grids a good cleaning after doing that?
DE Filter Use and Care - Further Reading
www.troublefreepool.com
Those grids do not look that great. I’d consider replacing them if that’s the clean pictures. They should be a very fine mesh. You could try an acid wash but you’ll likely make the grid brittle (I’ve not done this btw). It looks like there is build up on your grids. The quick pressure rise indicates this also but I’m only going off what you told me. Is the water clear?
You should be able to see the fins and it should be almost translucent when wet like this. 
Follow all the instructions here and if that doesn’t work you like need to replace them. DE Filter Cleaning Tutorial
Follow all the instructions here and if that doesn’t work you like need to replace them. DE Filter Cleaning Tutorial
Two thoughts come to mind immediately on reading your post
1) They're loading up because of algae
2) You may have wrecked them running them without DE for weeks.
1) They're loading up because of algae
2) You may have wrecked them running them without DE for weeks.
Thanks all. I still have this problem even though my water is clear. I suspect they need to be replaced. I will look at the DE Cleaning Tutorial first though.
Thanks Richard. What can cause grids to be wrecked if the system is run without DE? I don't have holes anywhere. Is the fibers get too worked and they expand?
Imagine getting pelted by high speed sand. They might draw blood. Pinholes. Then imagine the same but with a cushioning layer of DE sludge on you. No skin damage. That's one. Two, particles that should get stuck in the DE instead can get embedded in the grids.
The DE is designed to catch the dirt and then shed it all when cleaned. The grids are there to keep the DE in place. If the grids get used without DE they clog and don't clean up very well.