Scale and Rising pH over Winter

[Gaidal]

Hi,

I really appreciate this forum and the pool calculatory. As a former chemistry major it was extremely intuitive to me.

My troubles with my pool begin when I purchased our home 2.5 years ago. The pool was freshly replastered that year (2010) and winterized. I opened it to a high pH and some moderate scaling around the floor returns on the pool. I figured this was due to improper pool maintenance or issues with the new plaster. I found the BBB and installed a SWG that year and had an event-free summer. I opened the pool again last year with an off-the-charts high pH (despite closing it with it being around 7.5) but didn't notice any extensive scaling. In retrospect this was probably because I was not getting a particularly accurate CH estimate (either had a bum reagent or an expired test from my TF-100 kit) which was probably around 200.

So long story short, I close the pool with the following numbers: pH 7.5, TA 60, CH 300, CYA 70. I open it again this year with a pH off the charts (at least 8.2) and further extensive scaling seems to have developed, mostly as a "ring" around the bottom of the pool (very similar to how a shower tub develops a ring). My current numbers otherwise suggest good closing chemistry (TA 60, CYA 40, CH 200) so I can't figure out what's happening. So my two major questions are:

1) What are my options for scaling mitigation? I am aware of acid washing and the no drain compounds. Any strong opinions or success stories about either? What is a reasonable price to have a 20k gallon pool acid washed?

2) What in the world can I do to prevent this pH creep over the winter? Why is this happening? I suspect there was a material used in the plastering that was probably not appropriate for a pool that's winterized. Otherwise my MA requirement is not awful during the year (~1-2 cups per week of MA).

Thanks for all of your help and again appreciate this forum.

 

[frustratedpoolmom]

You can try to keep the ph at 7.0 for about 2 weeks or so and brush daily with an appropriate plaster brush to try and dissolve. I would suggest a submersible pump mid winter (you don't mention if you freeze or not) to circulate, test and add acid (and FC if necessary) as required throughout the winter months. I would also lower the PH to 7.0-7.2 prior to close - and what chemical did you use to shock pool prior to close?

 

[Gaidal]

I actually did not shock at closing. Just added the quat algecide.

I actually would be a little challenged to test the water over the winter with the safety cover on and the water being a few feet below the skimmer!

I'm in central Virginia so there is some freeze potential here for a few weeks of the year. More in a bad winter.

 

[msipos]

Hey I have had the same issue...live in SE PA with SWG 30k pool and have had ph always rising needing to add MA all the time including winter....use a pump to circulate as suggested....how are you doing past few years? Any words of wisdom for me? Now I am dealing with high CH level...

 

[frustratedpoolmom]

I actually did not shock at closing. Just added the quat algecide.

I actually would be a little challenged to test the water over the winter with the safety cover on and the water being a few feet below the skimmer!

I'm in central Virginia so there is some freeze potential here for a few weeks of the year. More in a bad winter.

Not suggesting daily or even weekly, more like monthly. Pop one of the springs and stick the pump in there for a few hours is all.

 

[Gaidal]

Thanks. Anyone have any particular recommendation for a cheap submersible pump I could chuck in there?

 

[frustratedpoolmom]

I would get a small one for under $100. You don't need much.