Algae is back! What did I do wrong??


Active member
Jun 4, 2016
New Orleans
I am new to this forum this season and started out with a very green pool. Did the SLAM procedure-Followed all instructions and everything balanced out and the water was beautiful.
I am using a TF 100 test kit and since I am fairly new at the bleach procedure I have been testing the FC daily since it cleared up and it has stayed at or above the target zone.

Today's levels
PH 7.5
FC 7
CC 0
TA 80
CH 375
CYA 60

I didn't like the look of the water today-Blue but just looked less clear. Brushed the sides and saw enough Algae come off that I thought I better
re-start SLAM -- but am disappointed--I thought if I kept the FC up I would stay algae free???

I did turn the filter time down to 12 hours a day about 3 or 4 days ago--is that not enough time? It is very hot here--90's+!

Any input is appreciated,


Well-known member
Jun 28, 2012
Butler, PA
When you were in SLAM did you pass all 3 criteria before you drifted out of it?
CC is 0.5 or lower;
You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
And the water is clear.

I am going to guess if your water is clouding back up you either didn't knock it out completely or you did knock it out completely, but since that time free chlorine dipped down and allowed something to get a foothold.


TFP Guide
Jun 5, 2012
Central PA
There are cases where due to circulation problems, etc., that the FC needs to stay at the top end of "normal" to avoid algae. Brushing regularly also helps. If the filter is undersized, a longer run time may be necessary.

I would run an OCLT to see if you need to do another SLAM.


Active member
Jun 4, 2016
New Orleans
Yes, I passed the 3 tests. And I measured the FC almost daily (think I missed one day) But can it go down and then back up??

I have a tree by the pool and it has been raining on and off-can that cause a new problem?

- - - Updated - - -

So If I don't pass the OCLT, then that is the criteria to start another SLAM?


Active member
Jun 4, 2016
New Orleans
I didn't do another OCLT as I could clearly brush green and was afraid to let it go over night. So went ahead with SLAM. FC was 30 last night, now down to shock level of 24, but still a bit cloudy. Brushing shows greyish instead of green so hoping tomorrow will look better.
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