DE in sand filter

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Jonsstihl

Well-known member
Sep 2, 2021
90
Quebec, canada
I seem to have an issue with my filter. Just finishing my slam and my filter seems to plugging up quickly when I add DE to it. I have a feeling this is normal but I would have to backwash daily if I keep adding DE.

without DE I can go several days almost a week without backwashing but if I add 1/2 cup of DE the next day My pressure is up past 15 PSI. clean pressure is normally 11.5 PSI. after backwash it doesn't always come down to 11.5 sometimes stays at 13. but the other day I guess I didn't have the pump basket cover on properly and I was getting air bubbles in the pump and return jet and that made the filter pressure go down by itself without backwashing. probably went from 14 PSI right down to 11 just from the bubbles.

I do think the guys that installed the filter added only filter gravel to the filter instead of sand. my guess is I should have gravel on the bottom and sand on the top or all sand. I still have a light brown sediment scattered in the bottom of my pool I am assuming is dead algae from opening and slamming. I have vacuumed once and it doesn't seem to come off. I guess I should brush then wait for it to settle then vacuum to hopefully remove more of the sediment.

anyone else having weird issues when adding DE to their sand filter. otherwise water is clear. I have a feeling my filter cannot filter out the light sediment so it is just pumping it around.
 
Jonsstihl said:
I seem to have an issue with my filter. Just finishing my slam and my filter seems to plugging up quickly when I add DE to it. I have a feeling this is normal but I would have to backwash daily if I keep adding DE.

without DE I can go several days almost a week without backwashing but if I add 1/2 cup of DE the next day My pressure is up past 15 PSI. clean pressure is normally 11.5 PSI. after backwash it doesn't always come down to 11.5 sometimes stays at 13. but the other day I guess I didn't have the pump basket cover on properly and I was getting air bubbles in the pump and return jet and that made the filter pressure go down by itself without backwashing. probably went from 14 PSI right down to 11 just from the bubbles.

I do think the guys that installed the filter added only filter gravel to the filter instead of sand. my guess is I should have gravel on the bottom and sand on the top or all sand. I still have a light brown sediment scattered in the bottom of my pool I am assuming is dead algae from opening and slamming. I have vacuumed once and it doesn't seem to come off. I guess I should brush then wait for it to settle then vacuum to hopefully remove more of the sediment.

anyone else having weird issues when adding DE to their sand filter. otherwise water is clear. I have a feeling my filter cannot filter out the light sediment so it is just pumping it around.
Click to expand...
Ive never added DE to my filter or felt a need to. But i understand you’re only supposed to add enough tonincrease 1psi.
 
So let's go over the theory of it all.

As the filter collects crud, the crud traps even finer crud. A dirty filter is more efficient to a point, and then it restricts flow with once there's too much crud in there.

Adding DE turbocharges the sand filter to the pretty dirty but super efficient stage and isn't for regular use. It's for polishing at the end of a slam, or to save time getting started in the spring.
 
OP, have you deep cleaned your filter this year? Might try that.

This is next bit is my personal experience. Once I was on the tail end of the slam, just trying to get to crystal clear, I would add 25% of the DE that was required to raise my filter pressure 1psi. To me, this helped clear the water better than without any but didn't require me to backwash the next day.
 
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the DE article says you may need 1 to 2 cups thats why i've tried 1/4 and 1/3 cup and it doesn't rise a noticeable amount after a few minutes it just plugs up in one day. I don't use DE year round either I am just trying to polish up after my slam.

But tonight I came home and pressure was at 17 but just turning the pump off then back on brought the pressure down to 13.5. I haven't deep cleaned the filter yet but I do drain the pool in the fall from the floor drain with a continuous backwash, takes about 30 minutes so I figure it is atleast well backwashed if not deep cleaned but it is on my list of things to try.
 
It would be wise to check the sand level in your filter. With the very long backwashes, you likely washed out some sand.
 
I have gravel in my filter I have seen a few puffs of gravel in the backwash sight glass but that seems to be new this year, I don't remember it doing that last year. and it doesn't do it every backwash. I contacted the filter manufacturer and they can't tell me what height the "sand" is supposed to be in the filter. they just said it should have X amount of lbs of sand in it.
 
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