Clear pool, good readings…found a swimmer bug in my pool today

[jolismom]

I’m fairly new to following TFFP. I have an above ground vinyl pool with approximately 13,000 gal.
FC -5
CC-.5
PH- 7.6
Alk- 80
CYA- 40
Every year I’ve been plagued with algae and so far this year I haven’t had any issues with algae…yet. I was adding the chlorine According to the app to reach 5. But by afternoon it was down to 2.5 and this was when it was not too hot here. I was worried that wasn’t high enough to keep the algae away so per suggestion on this forum I raised it to get to 9 ppm knowing that it would drop some. I add the liquid chlorine in the evening an I tested FC in the a.m. it didn’t drop but by late afternoon it dropped to 5ppm, which is ok but is it normal to drop that much? Should I up my CYA? I’m having to add quite a bit of chlorine each evening . Thanks

 

[jolismom]

I’m fairly new to following TFFP. I have an above ground vinyl pool with approximately 13,000 gal.
FC -5
CC-.5
PH- 7.6
Alk- 80
CYA- 40
Every year I’ve been plagued with algae and so far this year I haven’t had any issues with algae…yet. I was adding the chlorine According to the app to reach 5. But by afternoon it was down to 2.5 and this was when it was not too hot here. I was worried that wasn’t high enough to keep the algae away so per suggestion on this forum I raised it to get to 9 ppm knowing that it would drop some. I add the liquid chlorine in the evening an I tested FC in the a.m. it didn’t drop but by late afternoon it dropped to 5ppm, which is ok but is it normal to drop that much? Should I up my CYA? I’m having to add quite a bit of chlorine each evening . Thanks

I forgot to add . My pool is clear, no signs of algae that I can see. But, today that I found one of those swimmer bugs in my pool today. Does that mean I have algae?

 

[sande005]

Swimmer bugs can be tough critters - it will take a while to kill, if at all, if the Cl levels aren't pretty high.
Read up on OCLT - Perform the Overnight FC Loss Test (OCLT)
Important to add Cl just before dark, and give it 1/2 hr to mix. Then test as it gets dark.
Get up early the next morning - before or just barely at sun rise, and test again.
If you have no difference or no more than 1 ppm difference in the two readings, you are fine.
If more than 1 ppm, you have algae growing, even if you can't see it yet. Time to SLAM. SLAM - Shock Level and Maintain

Rain, dirt, pollen, swimming, and more can use up Cl, beyond what the sun consumes. If you pass the OCLT, you may want to bump up the Cl level closer to 7 when you add, which will leave a better margin to prevent dipping too low.