Ok, recommended or not good to close AT SLAM level?

[ionizer]

Just wondering if it is ok to close your pool at the SLAM level? Meaning actually putting the cover on over the pool while the chlorine level is at shock level based on corresponding CYA and the slam chart.

Not sure if the chlorine at that level is ok long term over the NJ winter. Since my CYA is around 60 to 80 (will of course retest right before) my chlorine level is accordingly fairly high as well.

Ok? Not ok? Or recommended?

Trying my to avoid opening the pool green like last year. This site has helped me leverage liquid bleach at 5 to 7ppm all summer and no need to shock all summer long.

 

[JVTrain]

It's perfectly fine to close at shock (SLAM) level for your CYA. Even more important than raising the FC to shock level is closing when the water temp is FIRMLY below 60 degrees. That's the single most important factor to opening to a non-green pool in the spring (and opening before it gets above 60...).

Typically I will raise to shock level they day before I close, so by the time I drain some water and get closing complete, I'm likely a couple FC below SLAM level.

 

[ionizer]

Close at less than 60 degrees eh? In NJ that might mean waiting until late October or even November. By then most of the pool closing people are done for the season!

 

[NYAVGUY]

I put the cover on my pool in mid to late September, but don't winterize it. I get all the chemistry perfect, bring the FC up to 1/2 of SLAM level (I have a vinyl liner and worry about fading if it doesn't go down quickly like summer). I also put in a Polyquat algeacide as a preventative measure. Per this forum, I wait until the temp is below 60 during the day. I usually bring the chlorine level back up and add some more Polyquat before I drain down the water to below all the openings. I then partially remove the cover to lower the water and blow out the lines.

In the spring I reverse this usually in the middle of April and de-winterize the pool to start putting chlorine back into the water before I am ready to open it sometime in May.

The one change I now need to figure out is I upgraded to SWG from an in-line chlorinator. I will need to either put bleach into the skimmer or powder shock into the skimmer to bring the chlorine back up before winterizing. There have been discussions on this and although it is not recommended, plenty of people do it with no proof of impact.