OCLT minor question

[acroy]

I plan to perform the test tonight to verify the pool is in good shape

How much will the OCLT be affected by windy conditions, and any minor debris in the skimmers/vacuum bag?

Should the pump be left running, or shut off?

Wind is a fact of life here, and we have lots of trees etc in the neighborhood willing to help pollinate the pool

 

[Bama Rambler]

Not much. Part of the reason the requirement is 1ppm or less loss is to account for stuff like that. Ideally in a perfect world you'd have zero loss but we don't live there yet.

 

[JasonLion]

You want the pump running for at least half an hour before testing. Also, you are also often doing the OCLT while shocking, which calls for having the pump on. However, the test its self does not require that the pump be running overnight.

 

[acroy]

I'm doing the test to verify if I have sneaky algae in the pool or not
Pool has always been crystal clear, but FC decreases faster than it should according to the math. Cell is undersized but I have it running enough hours it should easily maintain 4-5ppm. Instead, it drops 1ppm or so per day, down to close to zero - at which point I bump it back up to 5 with bleach.

Chemistry:
pH 7.8
TA 80
Ch 400
salt 3800
FC target 5, drops to 1, dose back up...
CC 0
CYA 75
Borates 50
Temp 73F

We're in the pool every day... Anything I might be missing?

SWCG should be able to maintain level with around 6 hrs runtime. It's running 12hrs a day and not keeping up. Cell is operating, it generates a ton of Cl in the bucket test.

 

[JasonLion]

Your numbers look reasonable, CH and Salt are both a tiny bit high, but nothing to worry about and certainly not something that would cause the problem you describe. A low level algae problem is the most likely cause, and doing an OCLT is a great idea.

 

[acroy]

Thanks again -
The SWCG specs 4k salt (older Polaris Clearwater system), and I deal with 120ppm Ch incoming water and lots of evaporation...
Will share OCLT results tomorrow!

 

[acroy]

Started at 2.5ppm and fell to 2.0ppm overnight. yay!

but it can't keep up with the need - it was at 5.0 2 days ago :grrrr:

So it may be time to look @ larger unit.... running this thing 12hrs a day, and only keeping up with 1/2 the load, is not sustainable.

 

[JasonLion]

Have you taken a look at the cell plates? If they have crusty white deposits that might account for the reduced chlorine production.

 

[acroy]

Cell plates are perfect - no buildup. I cleaned them when I first bought the house (1.5yrs ago) and kept the water in balance since then - no issues.

I think it may just be load related. We have 4-6 people in the pool most every day for an hour or more. 4 of them kiddos and no guarantee there's not wee-ing in the pool

 

[JasonLion]

Frequent swimming can dramatically increase the chlorine demand, so that makes sense.

 

[Bama Rambler]

4 of them kiddos and no guarantee there's not wee-ing in the pool

Oh yeah, a little ammonia will go a long way in sucking up some FC!