Unusual Die Hard Green Pool Problem

[Pool-owner]

Folks:

I saw the other posts about green pools. Not sure if it is weather-related this year.

I have dealt with green pools before and it usually went away after a couple of weeks. This year the problem lasted the good 2nd half of the summer and it just never goes away. Now it's time to close the pool. The decision is to close a green pool or try more...

Current reading:
FC 13
TC .5 or less
Ph 7.3
TA 100
CH 100-120
CYA 70-100 (I ran out of reagent, so the ready is a week old)

It's vinyl pool with about 25,000 gallons.

The NJ weather is usually dry and leaves started fall down in the middle of the summer. I SLAMed the pool early on but it might not have been aggressive enough. I also used the chlorine tablets which contributed to higher CYA. I have stopped using the tablets and used only liquid chlorine and powdered shock. (I also tried Kem-Tek KTK-50-0006 Pool - which I usually use for pool closing. I was desperate and also tried Natural Chemistry's First aid. )

The green pool has lasted 6 weeks. I am going to give it another week or 2. I will raise the chlorine level again to 20 to 25 for five days to see it makes any improvement. I have to cover it with a net because the leaves have become uncontrollable. (Pool is surrounded by trees). Please share your thoughts.

One Desperate Pool Owner....

 

[Divin Dave]

Hi,
raising the FC for only 5 days isnt going to help unless the SLAM is completed in that amount of time. ALL of the algae has to be eradicated or it will be right back in a flash. Once eradicated, you have to maintain the proper FC/CYA levels to keep the pool algae free.

To complete the SLAM, you have to stick to the process until the water is 1), completely clear, 2) you have .5 or less CC and 3) pass the OCLT

Also, the FC level for SLAM is 40% of the CYA. So for CYA of 70, that would be FC of 28 and for 100 it would be 40. Raising it to 20 is going to do nothing for you execpt perhaps slightly slow down the rate of the reproduction of the algae. Thats all it will do.

 

[duraleigh]

The first step is having the ability to test. You seem to have that based on the numbers you report.

The next step is to SLAM the pool. If you do it half-way. Your efforts are lost and the algae will happily return

 

[Pool-owner]

Dear Mates:

After 3 more weeks of slamming with many gallons' of chlorine, the pool is about 90 to 95% clear now.

I would rather wait until it's crystal clear but I want to close it this weekend before the storm hits.

The chlorine level is about 45 now, commensurate with the CYA level of about 90 to 100.

Is it okay to leave it like that when closing the pool?


Thanks a lot!

 

[kellyfair]

You said you ran out of CYA reagent. Did you get more, or are you relying on old numbers? I'm asking because you mentioned that you are now using liquid chlorine and powdered shock. If that's the case, your CYA may be higher now.