Help, Please! .5 Free Chlorine

[artd]

5 year old 27,000 gallon vinyl, IG pool, sand filter. (Fixed typo JasonLion)
First 3 years all good, last two can't keep chlorine in pool. Heer's the latest numbers:
hardness:250 ppm
CC: 0ppm
Free Chlorine: 0.5 ppm
ph: 7.2
Alk: 120 ppm
Cyanuric Acid: 50ppm

No matter how much 3" tabs of chlorine or liquid, or shock, same 0.5. I was told by pool place that I am not in chlorine lock.
Any suggestions? I am stumped and actually have water being tested at a Haviland lab for diagnosis. Last year i had pink slime and algae twice(probably due to low chl levels).

Thanks in advance.

 

[frustratedpoolmom]

Was your CYA higher last year?

 

[JohnT]

What does your water look like?

 

[artd]

water is slightly cloudy although I can see the bottom drain.
CYA was low when I opened but I added stabilizer to get listed numbers.
I put a sock on the skimmer baskets and that is pulling out pollen looking stuff which cleared up water to current state...better but not right.
The situation is confusing everyone around here, pool stores included.
Also, typo, it's a 27,000 gal pool

 

[JasonLion]

I suspect you simply haven't used enough chlorine but it is difficult to be sure. How much liquid shock have you added at one time?

 

[artd]

after opening, i added 5 gallons liquid chlorine within two days of 4 lbs granular shock.

Someone recently suggested I keep adding liquid chl until I get readings, even if it takes 10-15 gallons. Do you agree? Should I try clorox? If so, how much?

 

[frustratedpoolmom]

Use the best guess CYA chart to determine your shock level, then go to the pool calculator and it should tell you how much bleach to get. Clorox is a great choice, esp. if it's on sale.... WallyWorld brand is o.k. too.

 

[artd]

Ok, are you suggesting that I add roughly 14, 3 qt. containers of bleach(after my calc) to achieve a shock of 15 ppm free chlorine?

If so, should I do this throughout a 24 hr. period or at one time?

Thank you by the way. I am so eager to figure this out.

 

[JasonLion]

It takes 6 1/2 gallons of 6% bleach to raise your FC level from zero to shock level. So you should start by adding 6 1/2 gallons all at once in the early evening.

If you have a good test kit, you should then measure the FC level and add more chlorine to bring the FC level back up to 15.

If you don't have a good test kit you should really get one. I recommend the TF Test Kit, see the link in my signature. The Taylor K-2006 is also good. Failing that you need to do some guess work. You could try adding 6 1/2 gallons of bleach twice a day, morning and evening, for a total of at least four applications or until the water starts to clear up. Without a good test kit you risk using too little or too much chlorine and need to err on the side of using too much to have a good chance of killing the algae.

 

[artd]

Thank you. I will try that and also purchase the test kit. I currently use a strip tester and rely on a local pool store for in more specific diagnosis.

So you think I have algae?

thank you so much

--Art

 

[frustratedpoolmom]

The cloudy water could be an indication of algea.

Be sure to run your filter continuously until it clears...

 

[artd]

Thank you all so much. I am going to try the suggestions immediately.