Algae Maybe?

[Gary R]

Hi to all;

Opened pool a couple weeks ago and it seems like we're using a little more liquid chlorine than usual. FC dropped from 7 to 5.5 ppm overnight and during the day it drops from 6 to 2 ppm. I will probably slam pool up to 12 ppm starting this evening. Water looks clear and blue and no CCs (0.5) but I think I may still have a very minor case of algae.

CYA=30
FC=5.5
CC=0.5
PH=7.6
TA=80

Suggestions are welcome.

Regards,

Gary R.

 

[Texas Splash]

I think that's a wise choice Gary. SLAM now while water is still a bit chilly and algae is slow to get going. Giving your circumstances, it should go very well. Don't forget to lower the pH first to about 7.2.

 

[Gary R]

Yes, thanks for the reminder about the PH. Haven't had to do this before thanks to TFP.

Regards,

Gary R.

 

[Gary R]

Just a follow up.

Slammed pool to 12 last evening and it was 11.5 ppm this a.m.

By late this afternoon it was at 4 pm. We normally use 3-4 pm daily.

CYA is at 30 ppm, Water is clear and blue. PH=7.2.

Something's going on but not sure what.

Suggestions welcome.

Thank you,

Gary R.

 

[Texas Splash]

So you lost about 7ppm just during the day today huh? That's a significant drop. A few things you might consider:
- Double-check CYA to ensure you have the correct (matching) FC
- Maintain the SLAM for another 24-48 hours and do another OCLT at that time
- Deep clean your filter as noted on the Deep Cleaning a Sand Filter page

If after all of that you pass everything, it may just be time to raise the CYA a little to protect the FC from the sun. But be careful, you want to ensure everything else has passed first before doing that. Since you thought you saw algae before, and the CC was right at the top-edge, maintaining that elevated FC may be just what your pool needs to get healthy after opening-up this year.

 

[Gary R]

OK, many thanks for your help. I'm not convinced there is algae but better safe than sorry. The CYA has only been at 30 ppm for a couple days up from 20 so that may be part of the issue.

Regards,

Gary R.