Pool covered for winter - CH and CYA bit out of whack

[berniedp]

Hi all - could use some advice... My pool has been covered since Nov and my CH & CYA need work...

Note, before I start: my pool company has been doing my chemicals till recently so I'm taking over from them hence my question

My FC is at 10.7 - I guess that's because the pool isn't exposed to the sun at this time and my pool guys only asked me in Nov to lower the SWG - it's now set to 5%
The CYA is only 1 where I probably should have it at 70-80 (since I have a SWG)

My question - should I add stabilizer to bring the CYA up knowing that it will hold on to the FC even more or just wait till spring when I open the pool back up?

I'll definitely have to remember next fall to lower my SWG before covering the pool again

Thanks,
B.

ps. my other measurements in case they are important: pH 8, TA 51, CH 450

 

[mknauss]

How are you testing your pool water chemistry?

 

[ajw22]

Is your pump running on your covered pool?

 

[mgtfp]

Don't do any adjustments on CYA and CH (and salt) if the pump wasn't running to properly mix the pool water. The water can be really inhomogeneous over winter when the pump is not running. @Newdude just did some testing to show how significant this can be:

*update because I was bored.

I went back and used a 8ft piece of electrical pvc to get a bottom sample. Err. I'm sure there was some cross contamination, but it was mostly bottom water. To disturb it all as little as possible I first took a surface sample about wrist deep. Then I went elbow deep and then took the bottom sample.

The comparator block proved what I was expecting....... double digit FC down below (left side) and single digit at elbow deep (right side)

View attachment 471194


The fas/dpd said 9.5 FC and 3 FC respectively, with 0 FC in the top sample.

My CH was only a 50 or 75 to start so it was already low and its pretty cloudy today so CYA won't be too accurate, so i tested the salt for another example.

Wrist deep was 600 ppm
Elbow deep was 1600 ppm
Bottom was 3000 ppm

I closed Nov 19th and have this much variance in 72 days / 2.4 months. There is no telling how this will all average out without mixing well. Please nobody dose from their winter tests without mixing, and mixing well at that. A submersible pump won't move the same water that the pool pump can, but will achieve the same results if given a little longer to stir it up.

 

[berniedp]

Hi all,

Thanks for your help so far - to answer the questions:
- my pool pump has continued running 10 hrs a day ever since covering and my cleaning robot has been in as well
- I test my water with a Lamotte ColorQ 2x

Thx
B.

 

[ajw22]

No reason to add CYA until you remove the cover.

Your cover mesh or solid?

 

[berniedp]

No reason to add CYA until you remove the cover.

Your cover mesh or solid?

Solid - like thick blue bubble wrap