SLAMing and now white residue on floor, DE?


Well-known member
Aug 20, 2019
St. Louis, Missouri
These were my numbers prior to the SLAM yesterday at 8am
FC: 5
CC: 0
PH: 7.2
TA: 70
CYA: 60

I vacuumed around mid day, and was able to monitor the SLAM well.

Normal psi is 13/14 and I decided to add DE. Took about 2 cups to raise it to just over the 14 mark. By morning it was at 20. I tried vacuuming first, but that wasn't happening (not enough suction) so I backwashed with a 30 second rinse after (and had to add more water b/c of too much loss). It was down to 14, so I slowly added more DE. I got to 2 cups again, but the pressure never rose. I decided to wait it out until after vacuuming. Vacuumed, still no increase but figured I'd let it go for the day.

FC loss overnight was been fairly minimal, so going good with the SLAM.

BUT, now there are white piles in place of where the dirt/algae spots usually are. I'm guessing it's the DE? I did not noticed it coming out the return jet, but I don't know what else it could possibly be, especially in such a short time period.

I would have thought if I had added too much, my psi would have gotten higher.

So, question is, how to get rid of the extra? Just vacuum or vacuum to waste (hate doing that). Backwash again? Is it super problematic having it on the floor (like dangerous to kids or bad for the liner?)
Last edited:

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
It looks like DE. You'll just have to keep brushing it up to try and get it to the skimmer and/or vacuum. In either case, I wouldn't add anymor DE. Let the SLAM Process, specifically chlorine, do the work. The DE isn't for all pools and is only needed for some who pass the OCLT, have no CCs, but need just a tiny bit of help with water clarity at the very end. Many times that's not even necessary. Now something you may wish to consider if it's been a while is deep cleaning the sand. That can be very beneficial.

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