Alge, SLAMing, and DE filter


New member
Sep 18, 2021
Hey there,

fc: .25
Tc: .61
PH: 7.5
Ta: 93
Ch: 822
Cya: 50
Copper: .3
Phosphates: 1812
TDS: 3100

*EDIT* just did some more research. We have a multi valve filter. Should we backwash first, add more de, and then set to recirculate and start SLAMing the pool? Or backwash after we SLAM the pool on recirculate?

So, I'm new to pools. Our FC measurement is .25. Way too low, I know. And, of course, we have alge blooming. It's not awful, but there's more every day. And we have a de filter who's pressure is reading like, 27%. So, my question is, in what order do we tackle this? Address the filter then SLAM and clean algae? I know alge is notorious for clogging up de filters. So how do we manage the filter when we SLAM and clean algae? Thanks. Feel free to send me to any links that answer my question. I really did t know how to search.
Last edited:


Gold Supporter
May 20, 2020
Katy TX
Pool Size
Liquid Chlorine
Welcome to TFP. Based on your zip code I see you are in Austin, TX.
Suggest you post a picture of your filter and equipment pad as well as one of your pool.
You need to address the DE filter as that is needed to capture the dead algae unless you plan to vacuum to waste. Since you have a multi-port valve in front of your DE filter, it most likely has a setting for Waste.
Try to backwash first to see that drops pressure. If not, you will need to disassemble the DE filter to wash the grids to start fresh. You will need to add DE after the backwash or the full cleaning.

Also, based on the chemistry it appears those are pool store test results. Do you have your own test kit? If you want to do the SLAM Process to remove the algae, then you really need to have your own test kit as you will need to test the chlorine level 3-4 times a day to ensure you are at the SLAM FC level needed. If we can believe the test results you show, with a CYA of 50 you will need to raise your FC level to 20ppm. You will need to purchase liquid chlorine at Home Deport or Pinch A Penny.

You do not say how big your pool is so cannot advise how much chlorine you need to raise to 20ppm FC.

Let us know how you wish to proceed. See Test Kits Compared
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