Adding CYA and backwashing

[joshs2000ss]

It's been a long winter with no pool. I'm back here now, trying to remember all of the stuff I learned last summer. I have one question at the moment.

Opened the pool and CYA was 0 or close. I'm bumping it to 30 to begin the shock process because water was a bit green and stinky (haven't gotten an accurate FC reading yet). I added enough bleach to get the FC to 12 ppm and start the shocking process. I'd like to backwash one more time but I seem to remember someone saying you shouldn't backwash for a period of time after adding the CYA. I'm dispersing the CYA in two socks in front of my returns. It should all be out of the sock by now.

 

[Bama Rambler]

If you're doing the sock method it's fine to backwash. That's the whole reason the sock method was invented. That way it's not trapped in the filter waiting to dissolve so you don't lose much when you backwash.

 

[joshs2000ss]

Kinda what I was thinking, but I wanted to ask the experts.

 

[joshs2000ss]

Another question regarding CYA. I kept it at 70 through the season last year, however, when I opened the pool, before I started the shocking process, I tested the CYA and it was clear all the way to the top of the tube. If the only thing that gets rid of CYA is water replacement, then where did the CYA go over the winter. I might have had a 15% turnover with the draining and filling, but I wouldn't think that would zero it out. Does it just fade over time?

 

[JasonLion]

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.