CYA Levels

[hooeld]

Last Friday I tested my water, and the CYA was very high, off the scale of my tester(WalMart).. I drained 1/2 the water (abt 13000 gal Gunite pool). Refilled, and took some water the the pool place Sat. Here is their numbers.
TC 5
FC 5
CC 0
PH 7.6
ALK 135
CYA 110


So I drained another 1/2 the pool, and used the last of my CYA test,

My numbers
TC .2
FC .2
PH 7.8
Alk 110
CYA 80

I added some Clorine, and got the TC to 6, and it has stayed there for about 24 hrs..

My first question, is shouldn't 2 drains of 1/2 bring the CYA down more than that? I also assume I need to get that down, then take care of the ALK/PH by Airation??

Thanks
Les
That does not seem to me that the

[hooeld]

Sorry about the double post.. I can't see how to delete this one..
:eek:

[duraleigh]

Go to the post you wish to delete and click "edit"....you can delete it there.

Math says your CYA should've dropped more....I have no explanation unless you drained a little less than half.

80 CYA is manageable if you'll keep your Cl level around 5-10ppm constantly. Add enough muriatic acid to the pool to get down to about 7.2-7.4. The Alk will come down with it and shouldn't require any adjustment.

[JohnT]

There are some issues with CYA testing that indicate it may not be accurate above 100ppm. Many people have results of the same nature, which tends to indicate high CYA readings may be higher than the test shows.

[hooeld]

Water test this am by pool store:

TC 5 ( I think that is as high as they can read)
FC 5
CC 0
PH 7.6
Alk 120
cal 150
CYA 60

they called for 23.9 lbs Cal hardness increaser..

I plan to drain about 30% of the pool tonight, and try to get the CYA to 40, then address the rest.. I wan the CYA toward the low end, as I have a few Tab's I want to use up, slowly over time, so I want it to be able to raise a bit..

Am I on the right track??