Question on Shock

Jimh64 · Jul 20, 2011

My pool has not been very clear. Everyday there is some algea (dead) on the bottom of the pool that seems to be like dirt. My levels seem to be ok. Do I still need to shock?

Here are my levels:

FC 3.5
CC 0
PH 7.2
TA 110
CYA 40

Thanks!

Beamup · Jul 20, 2011

If you can see algae, you need to shock even if your test results are good. You're pretty close to the minimum FC for your CYA, so it's quite plausible that you've dipped below at some point and let a bloom take hold.

Jimh64 · Jul 20, 2011

Beamup said:
If you can see algae, you need to shock even if your test results are good. You're pretty close to the minimum FC for your CYA, so it's quite plausible that you've dipped below at some point and let a bloom take hold.

I have dipped below a couple times, so I think that must be what happend. Shock level is 16 for my CYA correct?

Beamup · Jul 20, 2011

Yep, that's what the Chlorine/CYA Chart says.

Bama Rambler · Jul 20, 2011

I'd suggest running the OCLT. That would be the definitive answer to whether you have something that you need to shock for.

Jimh64 · Jul 22, 2011

Bama Rambler said:
I'd suggest running the OCLT. That would be the definitive answer to whether you have something that you need to shock for.

Last night I took the pool to shock level. When I checked this morning, it dropped to 11 so I brought it back up to shock level again. I will check tonight and see what the level is. I think it is getting better though, becuase the water is getting more clear.

duraleigh · Jul 22, 2011

Last night I took the pool to shock level. When I checked this morning, it dropped to 11 so I brought it back up to shock level again.

Well, if you added the shock value chlorine after the sun was off the pool, you performed the OCLT and lost 5ppm.

Since the max allowed reduction is 1.0, your 5ppm drop suggests excessive organics in your pool (algae) and the very real need to shock. Be sure to get your FC right back up to 16 and keep it there until you meet these targets.

1. Your water is crystal clear.
2. You lose less than 1.0 FC during the OCLT.
3. Your CC's test is .5 or less