CYA too high

[Rob F]

My pool is white plaster (replastered 3 yrs ago). The last 2 years I've had to slam the water with liquid chlorine upon opening. I put 10 gallons of liquid chlorine into pool yes terday afternoon and by 1 pm today I had no FC and had about 1 to 2 TC. Never had to add liquid chlorine prior to the last 2 years. Pool is 32 years old. My CYA level is 60, within 30 to 120 range. I guess my question is how much water to get out of the pool to lower the CYA level and is this the correct action or should I do something else. According to the Slam chart I need to slam to 24. How much is needed of liquid chlorine to acheive that slam. The pool holds 24,000 gallons

 

[woodyp]

Here's what you wanna do with that kind of loss first:

Diagnosing:
1. Test CYA level and record result
2. With pump running, dose FC to Shock (SLAM) per level per Pool School - Chlorine / CYA Chart, then retest FC after 10 minutes. If FC level drops by more than 50%, then proceed with treatment for ammonia.

Treatment for Ammonia:
1. Begin a SLAM and dose FC up to SLAM level. Do not add additional CYA at this point.
2. Retest FC at 10-minute intervals.
a. If FC loss is greater than 50%, add FC to bring back up to SLAM level and continue retesting FC @ 10-minute intervals.
b. IF FC loss is 50% or less, add FC to bring back up to SLAM level. Go to Step 3.
3. If CYA is below 30 ppm, add enough CYA to bring level up to 30 ppm.
4. Continue SLAM as directed in the SLAM article until the SLAM Criteria of Done are met. Test as directed in the SLAM article - no longer need to test FC at 10 minute increments at this point.
*****

THIS!

To check and defeat ammonia, if necessary, is to raise your FC in the water using enough liquid chlorine to get to 10 ppm using PoolMath. Circulate the pool for 15 minutes. Test FC. If at 5 or below, add LC to get to 10 using LC, circulate for 15 minutes, repeat until your FC is above 5 ppm after the 15 minute circulation.

 

[Rob F]

I have a 23,000 gallon inground pool. My stabilizer level is too high, about 100, to slam. Anyone know roughly how much water to drain out to lower the stabilizer level?

 

[JJ_Tex]

I've never done it before, but read on here many times that it is equal to the % of CYA reduction you need. Need to reduce CYA by 50%, drain 50%. Need to reduce it by 75%, drain 75%...

 

[CrystalRiver]

If you drain half, you'll end up with half of what you started with. If you drain 3/4, you end up with 1/4 left.

Have you done a diluted CYA test? Half pool water and half tap, then run the CYA test using your diluted mixture. Double whatever reading you get for an approximation.

 

[CraigChing]

I checked your signature, but I don’t see what test kit you own. How are you testing your CYA? You should get your own test kit, TF-100 or Taylor K2006c and post your results. If your CYA is really that high, you can dilute your pool sample with tap water in equal proportions and double your CYA reading to get a better idea of your actual CYA level.

 

[brokenblinker]

Have you done a diluted CYA test? Half pool water and half tap, then run the CYA test using your diluted mixture. Double whatever reading you get for an approximation.

I am not OP, but I tried this for the first time yesterday (first time pool owner). The traditional method was giving us >100 CYA. When I tried the diluted method, I never got the black dot to obscure, and my measurement aid caps out at 30, so doubling that I measured 60 CYA (maybe less since dot was never obscured).

Any tips on which of these measurements I should trust more?

Edit: I just realized I was doing this wrong. I am supposed to use half pool water and half tap ON THE FIRST PART. I still need to add reagent. (I had been adding tap water as if it was the reagent).