CYA at 100, Chlorine unstable, well water has high TA, closing next week!

[Tiina]

HI, I am new to doing my own chemicals rather than the pool store's.

Question: My CYA is at 100. My chlorine depletes frequently. My well water has high TA and low pH. The pool is scheduled to be closed next week. So my concern is that if I drain some water and replace it w/ well water to reduce my CYA, my TA will skyrocket (always does), and my pH will be low - this is a constant problem for me. I don't think I'll have time to adjust the TA and pH to good levels before closing.

1) Is it ok to leave the CYA at 100 for the winter (Northern Indiana)?
2) Also, my cc is around .5. Will adding bleach to shock levels before closing take care of that? I've not added bleach to shock levels yet (just ran out of the ps shock tx).

Thank you!

 

[domct203]

Welcome to the forum.

There is no specific 'winter' CYA target, and you do not need to adjust just for winter.

A high chlorine demand, coupled with a high CYA level is usually a sign of algae/bacteria in the water.

How do you test the pool? Running an Overnight Chlorine Loss Test would show the real biological FC demand.

An occasional CC of 0.5ppm is fine for a clean/clear pool, but coupled with your FC demand I would suspect algae starting. How does the water look? Is it cloudy? Green?

Do you have the FAS DPD chlorine test? If you fail the OCLT you will want to SLAM Process the pool before you close.

 

[Tiina]

Thank you for your help - I very much appreciate it.

The water is a LITTLE cloudy. It was sparkling until today. We've had algae problems this summer, yes. Yes, I have the FAS-DPD chlorine test. I will do the OCLT and probably subsequently SLAM the pool.

This chart Pool School - Chlorine / CYA Chart says that if my CYA is at 100 that
1) that is not ideal and
2) that my FC should be kept at 8.

Yikes. I barely keep FC at 2. When I SLAM the pool, will the CYA come down? If not, do I really have to keep my FC at 8?

 

[domct203]

Thank you for your help - I very much appreciate it.

The water is a LITTLE cloudy. It was sparkling until today. We've had algae problems this summer, yes. Yes, I have the FAS-DPD chlorine test. I will do the OCLT and probably subsequently SLAM the pool.

This chart Pool School - Chlorine / CYA Chart says that if my CYA is at 100 that
1) that is not ideal and
2) that my FC should be kept at 8.

Yikes. I barely keep FC at 2. When I SLAM the pool, will the CYA come down? If not, do I really have to keep my FC at 8?

Your absolute minimum FC is 7.5% of your CYA, daily target is 12-15%, so yes, maintain a minimum of 8ppm FC, and target 11-13ppm when you dose. this will be the equivalent of a FC of 1-3ppm in a pool with zero CYA.

To reliably lower CYA, you drain and then refill to dilute. With an IG vinyl liner, you should never drain below the ground water level, or lower than 1 foot deep in the shallow end, which ever is higher. This will prevent your liner from floating and shifting.

 

[Tiina]

Thank you! Would YOU lower your CYA if you were me? Now? In the spring? Or not worried about it?

 

[AftonJeeper]

I wouldn't worry about CYA now. You will lose some when you close and about 3-5ppm per month over winter.

When you open the pool if CYA is still over 90 I would do step 8 of the CYA test detailed here: Pool School - CYA

High CYA is only big issue if you have an algae outbreak.