another cya question

ethany

LifeTime Supporter
May 23, 2009
516
0
Trenton NJ
#1
I read in the other post that you lose cya due to splash out and sometimes over the winter. When I closed the pool last fall my cya was around 60-70. I opened today and tested with my taylor kit, no cya. Possible to lose all cya over winter?

I am currently putting in 6 lbs. I know I will need more. What does 6 lbs. get you?
 

jblizzle

Mod Squad
LifeTime Supporter
TFP Expert
May 19, 2010
41,193
4
Tucson, AZ
#2
We have seen that happen before here on the forums. Could mean that it was all converted to ammonia which will require a lot of FC to break it down (or sometimes not).

According to the poolcalculator (at the bottom) adding 6 lbs to a 20k gallon pool should give you 36ppm CYA and lower pH by .67

If you need to go through the shock process, do it with this lower level of CYA BEFORE you raise it higher to the SWG recommended levels.
 

Isaac-1

LifeTime Supporter
TFP Expert
May 10, 2010
6,711
1
49
SW Louisiana
#3
This can be common when you have a swamp like pool, there are bacteria that can convert all your CYA to Ammonia, chlorine will react with the ammonia and be consumed rather rapidly so if the ammonia is still present expect to need lots of initial chlorine before you can even start the shock process to kill anything growing in the water.
 

Butterfly

LifeTime Supporter
TFP Expert
May 31, 2007
10,045
1
68
South Carolina
#6
When I closed the pool last fall my cya was around 60-70. I opened today and tested with my taylor kit, no cya. Possible to lose all cya over winter?
CYA is sometimes lost over the winter. It is believed that this is caused by anaerobic soil bacteria that can sometimes grow in pool water when the pool is covered and FC levels are zero.