Algae Back After SLAM Even Though FC is High

[Joe Garcia]

About a month ago I want away on business and came back needing to SLAM my now algaed pool for the 1st time in years. I brought the FC up to about 30 using a combination of liquid bleach and 4 pucks that I had put on the pool floor to cover some black algae spots. My CYA is at 60 so I was okay with a free FC of 30 for the SLAM.

After following the usual SLAM recommendations from TFP, the algae was gone and my filter clean and white in a few days. Water was crystal clear. My FC was still high (over 25) so I kept an eye on it waiting for the chlorine to burn off and FC to return to normal levels.

Over a week later, my FC went down to 15 but now I have a slight dusting of algae. As of today, my FC is at 11.5 with a CC of 0.5. I also added a little too much Muriatic acid to the pool and brought my PH down to 7.2. The pucks stayed is place for a week and are gone, but my FC is dropping very slowly and the algae is backe3

 

[duraleigh]

Algae cannot exist in the presence of adequately chlorinated water. So, I am not sure what you have but those are not algae-producing conditions. Got any pics?

 

[Bperry]

About a month ago I want away on business and came back needing to SLAM my now algaed pool for the 1st time in years. I brought the FC up to about 30 using a combination of liquid bleach and 4 pucks that I had put on the pool floor to cover some black algae spots. My CYA is at 60 so I was okay with a free FC of 30 for the SLAM.

After following the usual SLAM recommendations from TFP, the algae was gone and my filter clean and white in a few days. Water was crystal clear. My FC was still high (over 25) so I kept an eye on it waiting for the chlorine to burn off and FC to return to normal levels.

Over a week later, my FC went down to 15 but now I have a slight dusting of algae. As of today, my FC is at 11.5 with a CC of 0.5. I also added a little too much Muriatic acid to the pool and brought my PH down to 7.2. The pucks stayed is place for a week and are gone, but my FC is dropping very slowly and the algae is backe3

Are you sure it’s algae and not just dirt? You can perform an OCLT to confirm.

Looking through your logs it would help if you put all the test results from one day into the same log. That way we can see the trend over time much easier.

 

[Newdude]

Water was crystal clear

I don't like seeing this reported. I like seeing 'I passed the OCLT with 0 loss'. I really REALLY like seeing 2 OCLTs passed with flying colors.

So I'm just making sure it was done. If so, do another as suggested above and if that passes then it's environmental debris (fine dust/pollen) that isn't consuming FC.

 

[Joe Garcia]

Are you sure it’s algae and not just dirt? You can perform an OCLT to confirm.

Looking through your logs it would help if you put all the test results from one day into the same log. That way we can see the trend over time much easier.

I have had a pool deck full of people 2 consecutive days over the last few days so dirt could certainly be a possibility. I'm going to perform two OCLTs and get back to you with the results.