CSI Balancing over the wintertime

[trivetman]

The last couple of springtimes, Ive opened to a pool that has 1) a lot more scale buildup than what i closed with and 2) a lot of crystalline precipitate in the bottom of the pool. It fizzes with acid so assume its calcium (calcium carbonate??) 3) ph high well over 8.0.

This winter, Im hoping to keep the csi/ph a little more maintained if possible to hopefully open up without scale and a big precipitate mess. But thats hard to do when the ph to maintain balanced CSI is over 8.0 (8.2 with 40 degree water). The last thing I want to do is pour in a ton of acid over the winter and then when the water warms in the spring find out I way overshot and have an acidic pool.

Also its worth asking….is the poolmath csi equation valid at temps this low?

Im inclined to put enough acid in so the ph seems to be just a bit above 8 and hope for the best. I won’t be able to maintain this on a regular basis but am hoping to check it every few weeks until the springtime. Anybody think this will lead to trouble or is it just not worth doing?

 

[Texas Splash]

I personally would leave it alone until spring. Assuming your pool is closed, so there is o reliable way to mix chemicals and/or get a valid water sample for testing. The Poolmath app does take into account all variables, including colder water temps. Let the pool sleep until spring and rebalance at that time.

 

[trivetman]

Mixing isn’t an issue. I have to drain periodically over the winter with a small sump. I can recirculate with this as well prior to sampling and also for mixing.

 

[onBalance]

The CSI is valid at low water temps.
I would like to know what the age of your pool plaster is?
And what were the latest pool water tests for pH, alkalinity, calcium hardness and CYA?

 

[trivetman]

@onBalance -

Plaster was resurfaced in 2019.

I opened it up last week for a drain and tested PH well over 8.0. Despite @Texas Splash telling me not to bother , 3/4 gallon of MA brought it down to ~7.7

When I closed in October:
Ph: 7.7
TA: 70
CH: 480 (last tested in August)
CYA: 60 (last tested in August)

FWIW - the pool needs regular MA additions to stay balanced. I probably use close to a gallon a month over the summer, injected daily with a Stenner.
Also, I am aware the CH is high. I accidentally put in too much last spring. My fill water is fairly soft and the drain/fill cycle should bring the CH down in the spring.

 

[onBalance]

The calcium hardness okay.
I also think the current pool water results are good as is for the winter. I wouldn't change a thing.
Your plaster happens to be releasing calcium hydroxide and cannot be stopped regardless of the water balance. But it should become less of a problem in the near future.