Errrr!!! I am sooo not a chemist!!!!

[cherylandco]

Well, I am now joining the ranks of those fighting the algae growing on the bottom of the pool. My water is actually still crystal clear as it has been all summer, but that stupid algae is growing on the bottom of the side opposite my return and skimmer (probably another argument for putting in that 2nd return next year!!!).

But my question - HOW does the CYA just disappear? We have not replaced any water in probably a month.

7/14 my readings using TF100 test kit:
FC 5
CC 0-0.5 (could barely see a hint of pink when put the R0003 in)
TC 5-5.5
ph 7.4
T/A 90
CYA 45

We went on vacation then 2 days later Thurs-Sun (7/16-7/19), and we had the neighbor girl add .75gal clorox to the pool on Friday night, then I added more on Sunday when we got home. Readings similar until now the algae shows up. My readings last night 7/31:


FC 6.5
CC 0
TC 6.5
ph 7.5
TA 110
CYA --- 0 ---

Now I wanted to retest, but I am out of the stuff - apparently tested too often for CYA (just got the test kit about a month and a half ago)

What the heck happened to my CYA??







af

 

[pitguy3]

I'm gonna have to bookmark this post!! Mine is doing the same thing... Although we have had a TON of rain over the past few days... I bet I've pumped 4-5 inches of water out of mine! Can't WAIT to see what the experts say!!

 

[dmanb2b]

go ahead and perform the overnight FC drop test...it may be time to shock.

 

[duraleigh]

I can't help with the CYA. I'd get another test result from another source. It's unlikely your CYA has disappeared....not impossible, but unlikely.

If you have algae, you need to shock your pool to get rid of it. As soon as you confirm the presence or absence of CYA shock according to the CYA/chlorine chaert and get more CYA in your pool if necessary.

 

[TizMe]

I would shock like Duraleigh says and maybe take a water sample to the PS and see what they tell you. You need some sort of CYA reading so you know what your shock level should be.
I would think in this case it would give you and idea if it was relatively close to your previous level ... IMO

 

[cherylandco]

go ahead and perform the overnight FC drop test...it may be time to shock.

I've been shocking the last couple nights. We are having company to spend the night though today, so I have to let it get back to a level which is ok for swimming. But I'll be back to shocking as soon as their car clears the driveway tomorrow!!!

I got in when it was at FC 8.5 this morning, and it seemed ok. What is the highest the FC can be and still be safe to swim in??

 

[reebok]

without knowing your cya level it's impossible to tell. if your cya is really 0 then no more than 3 or 4ppm. otherwise, some are ok with shock level according to your cya (see chart). some like it lower than that.

 

[Ohm_Boy]

What is the highest the FC can be and still be safe to swim in??

Well, that depends upon the CYA level. It's the CYA that determines how much effective FC you have from your available FC. Generally speaking, anywhere from minimum to shock level on the CYA chart should be fine.