Draining & Refilling due to too much CYA ?

Tbell

Well-known member
Jun 20, 2010
138
Tennessee
Hi , I am new & have a couple of questions. I have a 30' Round 21,000 gal. Vinyl pool that I have owned now for almost 10 years. I have a Hayward 1.5 HP pump and 18" Sand Filter. I opened my pool last Sunday (later than usual) and it was of course Green with the tadpoles included. I got rid of the algae but could NOT get the PH or Alkalinity right. Went and had water tested yesterday at the pool supply ... Chlorine level was practically nothing, PH was too low...alkalinity was at 30 ppm...Calcium was at 70 ppm and CYA was at 184 ! I drained over half the water and am in the process of refilling now. It is going to be 97 degrees for the next 4 days...I have the pump running 24 - 7's. Do I need to add any bleach or liquid chlorine while pool is filling? I use well water and my pool only fills an inch an hour so will take a considerable amount of time to fill. After it is filled what is the first thing I need to adjust? PH? and then what next? I started using baking soda and borax 2 years ago but still stuck with 3" chlorine tabs as my main source of sanitizing for the simple reason of not knowing how much liquid bleach to pour into that many gallons of water. It tried the bleach two years ago but could never get enough in the pool to be right. Any help would be appreciated.
 

frustratedpoolmom

TFP Expert
LifeTime Supporter
In The Industry
May 20, 2007
12,177
SWSuburban Chicago, IL
Yes, adjust ph first, then ta then start adding bleach. You really need to have a way to circulate when adding chems.

If you can learn to use the pool calculator, it will help you to determine how much to add. Have you read Pool School?

What are you testing with?
 

Tbell

Well-known member
Jun 20, 2010
138
Tennessee
Yes I have read pool school...just getting old and my mind doesn't ratain much. LOL! I have pump running through main drain...top skimmer turned off until water level reaches skimmer. I have looked at the pool calculator just haven't figured it out yet. But I will. Thanks so much for the help. I just don't want algae to start growing again while pool is filling. It is soooo hot here.
 

Tbell

Well-known member
Jun 20, 2010
138
Tennessee
I just read by using the readings I had done at the pool supply that with my CYA reading being at 184 I should have drained 78% of the water. I only drained right at half. Do you think I will be okay? If it brings the CYA down to say 90 or 100 is that still too high? I know it will cause me to use more chlorine...also are all granulated chlorines stabilized. I have some granular I would like to use up before putting bleach in and I didn't see where it said anything about it being stabilized. I just don't want to use anything else with Cyanuric Acid.
 

Tbell

Well-known member
Jun 20, 2010
138
Tennessee
Oh and to answer your question about what I am testing with...just using 6 way color test strips from WM. I know...I know! LOL!
 

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