CYA through the roof

[SLackuR]

Hi I was using test strips for the last few years with no issues in balancing as far as I know. Never any algae and the strips read in "ok" ranges.

Recently I noticed 2 or 3 green spots about the size of a silver dollars near the main and the water didn't seem as clear. Also the CC and FC were reading practically 0 on the test strips even though I feel I was burning thru the 3" tablets quicker than in the past.

Anyway I decided to get a k-2006 and first test my CYA was well over 100. The dot disappeared within a few drops. So I drained about a 3rd of the pool over night and refilled. I let the pump run for a few hrs before getting another sample and the CYA test is about the same. How much should I drain? Should I just drain it completely and start over? I intend to slam once I can get cya in the proper range.
Thanks,

Current levels after the partial refill.

PH 7.4
CC 0.2
FC 0.4
TA 120
CYA well over 100.

 

[Rancho Cost-a-Lotta]

Great job on getting a good test kit. You need to do a diluted cya test. Dilute the pool water sample with 50% tap water. Rerun the cya test, but double the results. This will get you in the ballpark unless you're over 200 PPM.

 

[Rancho Cost-a-Lotta]

Here are more detailed directions from Pool School...

If your CYA level is 90 or higher, repeat the test adjusting the procedure as follows:

Fill the mixing bottle to the lower mark with pool water.

Continue filling the mixing bottle to the upper mark with tap water.

Shake briefly to mix. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.

Continue the test normally from step 2, but multiply the final result by two.

 

[SLackuR]

Great job on getting a good test kit. You need to do a diluted cya test. Dilute the pool water sample with 50% tap water. Rerun the cya test, but double the results. This will get you in the ballpark unless you're over 200 PPM.

Oh thanks for that I wasn't sure how to get a reading. After the diluted test I'm at 150. Do you think I should drain it all the way down? My pool isn't every big 10k gal I'd guess.

 

[Bperry]

Oh thanks for that I wasn't sure how to get a reading. After the diluted test I'm at 150. Do you think I should drain it all the way down? My pool isn't every big 10k gal I'd guess.

Draining half the water will get you down to 75ppm CYA. But be careful draining if you have a high water table.

 

[Rancho Cost-a-Lotta]

It won't quite require a full drain, but drain enough to get your CYA into the 30ppm range. You're going to have to SLAM after refilling to clear the algae if still present.

 

[SLackuR]

Dumb question after a partial drain how long would you let the pump run before pulling a sample to test? It shouldn't take too long to mix right?

 

[Rancho Cost-a-Lotta]

30 minutes to an hour should be plenty of time.

 

[Rancho Cost-a-Lotta]

What are your plans after you get your water in check? Hopefully your future plans do not include tablets. Switch to liquid chlorine or look into installing a swg. These are really the only two sustainable options.