Question about CYA

[Durangler]

Hello everyone.
Received my Taylor K-2006C kit late yesterday and did some testing this morning.
Numbers:
FC - 4.0
CC - .5
pH - 7.7
TA - 250
CH - 725
CYA - ?? Somethings wrong
I did an OCLT last night, using my old 5 way kit. At 7:30 pm FC was 3.0. This morning at 6:30 am FC was 2.5.
So, performing the CYA test, the black dot disappeared well below the 100 CYA number. It was closer to the 1.8 mark on the side of the small tube. Does this mean the CYA is extremely high?
I've used chlorine pucks for years, not knowing better, until I found this forum. The pucks have been out of use for almost 2 weeks. Using 10% bleach now. I figure I need to drain and replace water to correct this problem.
Thoughts, please. Thank you.

 

[mknauss]

The CYA is high.
100 is the limit of the CYA test, so you have to do a diluted test. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. Multiply the result by 2 for your CYA level.

If the CYA is higher than 200 - then a close to full drain is needed. Your CH is at about the level it is needed anyway.

 

[Durangler]

Thank you.
Yeah, CYA is near 300.
Would rather wait until winter to exchange water.

 

[mknauss]

You can do that. Keep your FC well above 15 ppm to keep the pool water sanitary. Your pH will be difficult to measure.

 

[Donldson]

Minimum FC for a CYA of 300 is 24, target is 33-39 ppm. You will be unable to get a pH reading at those levels.

Your OCLT shouldn't really be considered concrete since at 300 ppm CYA and 3 ppm FC your active chlorine level is crazy low. The equivalent of having 0.01 ppm FC in a pool with no CYA. Well below what would be considered safe to swim in, in fact.

 

[mknauss]

With your pool water conditions, an exchange will be fairly efficient.

Read Draining - Further Reading

 

[Durangler]

Wow.. 15 ppm!
Okay, I'll start pushing it up to your recommended level.
Is it safe to swim at 15? Does the high CYA number allow swimming?
Water is crystal clear now.
Thanks again.

 

[Durangler]

Just saw Donldson's post. Thank you.
I'll read your link, Marty, Thanks

 

[Durangler]

Guess I'll head to Ace for several more gallons of their $2.99 liquid chlorine that's on sale.

 

[Durangler]

Ok... I have a delima. For the last week & a half, I've been using Liquid Chlorine exclusively. It's been close to 1/2 gallon a day to maintain 15ppm FC, due to high CYA (numbers above) So... It's been hot here for the last 2 weeks (105F+) and is going to be that hot for another few weeks, until the monsoon brings rain. I'm planning a drain and refill in the fall after it cools down to the 90's. Thoughts on using pucks at this point, knowing I need to drain water and save the LQ after the refill. Or will the pucks not keep FC at the range needed?
Also, anything I should be aware of regarding pH? Add a bit of Muriatic Acid occasionally?
Thank you.

 

[mknauss]

I really encourage you to consider the water exchange. Have you read the article I linked?

 

[Durangler]

Yes, I've read the links. Will take a week or so to gather stuff for the exchange.