Opening Lessons Learned from Closing


Bronze Supporter
Jun 25, 2020
Pittsburgh, PA
I just opened my pool and learned a few things about closing I'd like to share.
I closed early October, when the leaves were really falling. It was a battle to keep the pool leaf free, but I managed to keep the pool pristine. Just as I was pulling the solid safety cover on, a gust of wind blew in a bunch of leaves. Most sank to the bottom... drat!

Fast-forward 6 months to April 5... Opening day!

Opened the pool to a perfectly full, though slightly cloudy 55 degree pool with a gray layer of slime all over the bottom. Not too many leaves, 1 or 2 worms, and a FC of 1. Fired up the pump, and discovered that the bypass valve for my heater was spraying like an MGM Grand fountain. I had forgotten to leave it open after blowing out the lines and disconnecting the heater. After that was fixed, I fired up the pump again, vacuumed the pool, and began the SLAM to clear the water.

Decided to run water through the heater.... and discovered the heater was leaking. Turned out the return manifold needed to be cleaned and reseated. Easy enough fix.

Lessons learned:
1) NO leaves when closing. If some blow in, stop, remove them, and then close. Pristine is the goal.
2) Double check to make sure ALL valves are set to the open position. Water trapped in a closed ball valve will expand and crack the entire assembly, even if it is made out of thick PVC.
3) Follow the chemical recommendations on this site for how to close the pool. I still had chlorine 6 months later. 1ppm, but the water wasn't green, just cloudy.
4) This year, I am going to close a few week early to avoid the crazy leaf fall. We really don't use the pool much after school starts, so closing it in early - mid September is probably fine.

Good things that happened.
1) My CYA is FINALLY low after multiple drains last year. It's 30. I drained the pool at the end of the season and let snowmelt and rain water fill it back up, PoolMath is recommending I add CYA to get it to 40 to be ideal. I don't know if I will or not. 30 might be ok, though today I had a loss of 4.5 FC in full sun over 8 hours. BTW, there is a great chart here that shows FC loss based on full sun per CYA. I used this to verify my CYA reading, and I think it is within errors.
2) the water level was perfect when I opened. No need to add water, no need to drain. (the solid safety cover has a mesh piece for the water to drain through)
3) I only lost 1 FC OCLT and have a 0 CC reading. So I am hopeful I won't have to slam too long for the water to clear. I'll be adding a skimmer sock to see if that helps, but I have the robot cleaning frequently, too.


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Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
Sounds good! Being in Pittsburgh, I'm not sure if you need 40ppm of CYA either? But if you lose too much daily FC you'll know the extra CYA to 40ppm should help.

Good job opening to 1ppm FC and a full pool! :goodjob:

Maddie :flower:


Well-known member
Sep 4, 2019
SW Ohio
I’ve never seen that chart reading through the forums over time. It gives a good perspective on potential fc loss in relationship to cya. Thank you for linking and sharing.
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