CYA too High

[sands74]

Here is my situation and hope I can get a little bit info on what may be happening with my CYA problem.
I have an AG pool (12,500 gal). Sand Filter with 1.5 Matrix Pump.

Had a nasty,ugly pool with lots of algae when I opend it this season.

Within the last few weeks I have been trying to lower my CYA level down, due to it being high from the use of clorinating powder shock from the pool store.
It raised the CYA level way over 150 with this stuff from the pool store.
So, I opted to change over and use Bleach and/or liquid chloring versus the powder stuff from Leslie's.
I have drained the pool twice 50% both times, which should give me a much, much lower CYA...... But my CYA reads still at 100 or 90. I have even gone as far as buying new reagents in hopes that maybe the ones I was using had gone bad, but I get the high readings even with the new reagents.
Being that I have replaced almost all the water, why am I still getting a CYA..
I am no longer using the powder from Leslies to shock the pool and have been using 10% liquid shock from Lowes that I purchased by the cases. been dumping 3 in the morning and 3 in the evening to maintain a high shock level.

Here are my other readings:

FC 2
TC 2
CC 0
PH 7.6

Can someone give me an idea why my CYA is still so high, even after replacing all that water.
I want to lower the CYA level, so that my shock levels will be a little less than what I am using now.
Thanks in advance for any info someone can send out on this issue I am having.

 

[macgulley]

Unfortunately, at very high levels the CYA tests seem to "top out" and your CYA may have been much more than the 150 you read. The only solution I know of is to drain and refill again until you reach a reasonable CYA level.

 

[sands74]

That's what I am thinking I am going to have to do again.
Another reason to stay away from using the powdered chlorinators and stick with plain old bleach or liquid shock.

 

[jblizzle]

The CYA test only goes up to 100 and it is logarithmic ... so if the test was half way below the 100 ... that could be 200-300+ ppm.
That reagent also rarely if ever goes bad. You can try using a 50/50 mix of pool water and tap water and then double the test reading to get a better idea where you currently stand.

Then continue to replace water. BTW, two 50% water changes does not replace all the water ... it would have reduced your CYA by 75%

 

[Stuamurr]

The CYA test only goes up to 100 and it is logarithmic ... so if the test was half way below the 100 ... that could be 200-300+ ppm.
That reagent also rarely if ever goes bad. You can try using a 50/50 mix of pool water and tap water and then double the test reading to get a better idea where you currently stand.

Then continue to replace water. BTW, two 50% water changes does not replace all the water ... it would have reduced your CYA by 75%

^This and if the first dilution 1:1 test still reads high then goto 1:3 parts pool/tap water and so on until you get a reading which can give a more definitive range of your CYA.