TA and CH readings are very low...should I adjust?

[three4rd]

Hi,

I have not checked readings since November. We're just at the point here in PA where the water is starting to freeze over on the surface. Last year, with the new plaster, I was worried about scale and so several times had to lower the pH. Now, however, I seem to be looking at the opposite problem and am concerned about etching. I'm getting an SI of -0.9 due to the following readings

pH - 7.6
TA - 60 (can this be right?)
CH - 100 (can THIS be right?)
TEMP - 42

I took the sample right from the skimmer bowl - which is not always entirely accurate but generally close. Also, the pool water level is up over the tiles and so I am theoretically sampling 'pool' water and not just accumulated rain water in the bowl. How could I have gone from CH of 190 back in November to 100? And how from a TA of 95 back in November to 60? I almost have to pull back the cover part way and get a sample from the pool, but might not be able to if there is too much ice.

Should I be concerned, or just leave it as is? I don't think I can adjust the CH with the water being this cold anyway (?)

Thanks,
Keith

 

[duraleigh]

I understand the issue of getting a good sample, but I don't like the sample from the skimmer at all......I do not think it is representative of your pool water.

My first thought would be to figure a way to get a good sample of your pool water and compare.

 

[borjis]

agreed. I would wait for a thaw and run the pump a couple hours then sample from the deep end.

My TA is down from 70 to 50 due to rain fills and draining down to skimmer level.

 

[three4rd]

agreed. I would wait for a thaw and run the pump a couple hours then sample from the deep end.

My TA is down from 70 to 50 due to rain fills and draining down to skimmer level.

I would not plan on running the pump being that the entire system is drained and antifreeze in the lines. I just use a kayak paddle (lol) and agitate the water for several minutes...probably still not a great sample but good enough I suppose.

- - - Updated - - -

I understand the issue of getting a good sample, but I don't like the sample from the skimmer at all......I do not think it is representative of your pool water.

My first thought would be to figure a way to get a good sample of your pool water and compare.

Yeah...I'm not content with the skimmer sample. I'm thinking that the CH reading I'm getting is probably mostly from rainwater and ice melt - since there was a decent amount of ice in there when I took the sample.

 

[zea3]

You can use a length of flexible tubing to slip under the cover and siphon a sample from 2-3 feet deep in the pool, however if you closed with a CH of 190 you were already too low. Minimum CH for a plaster pool is 250. It would be difficult to add CH while the pool is winterized since the added calcium may not dissolve well in the cold water.

Most likely you are correct that the skimmer sample is rainwater and not representative of the bulk of the pool water. You can try and siphon out a better sample to test, but if the calcium is low it will be difficult to correct without opening the pool.

 

[three4rd]

I took off part of the cover - as I usually do when checking the water and adding any chemicals during the off-season. It turned out I was way off. The true readings are:

pH - 8+ (guessing around 8.2 or 8.3)
TA - 130
CH - 230

So I'm a bit in the scaling zone...added some pH decreaser, agitated the water around for several minutes, and then reattached the cover. That should do it probably until I reopen in spring. I might recheck in a few weeks unless the pool is frozen by then. Thanks to all who replied. I have to remember not to rely on water samples from the skimmer any more.

 

[borjis]

You hadn't mentioned you were at winterized levels in the first post so, yes my idea would not work.