My plaster (Quartz) pool was completed this spring. The last 2 tests I have done for CH are showing very little calcium so I am going to go buy some today. I just want to make sure that this is all normal. When the pool was started the CH was very high (600) and I have never added anything to it. I learned it was due to the new plaster and that it would balance as the plaster aged. SO has it now just reached the age that it is not adding calcium to the water any more? I just want make sure I am on the right track and not missing anything!!

Here are full numbers from today...

FC 5 (raising to 7)
pH 7.8
TA 80
CH did not get any red on test
CYA 50

THANKS!!!

CH does not normally fall noticeably unless you have massive amounts of water replacement going on. The only way I would expect CH to go from 600 down to around 0 is if you have a leak and an autofill system replacing water constantly. CH does drift around some, just not that much. A drop of 100, or even 200, wouldn't surprise me (even though increases are much more common). But going down from 600 to near zero is just too much to be normal.

We do not have an autofill and we have not added any noticable amount of water. Could any of the testing chemicals go bad? I did do a strip test just to see if I would get a reading and it said about 500 so I will test again tomorrow and see if I can figure it out. Any other suggestions would be helpful!

It is possible for the test reagents to go bad, but it is fairly unusual for that to actually happen.

If you haven't already, now might be a good time to read the Extended Test Kit Directions for the CH Test. There is always some chance that you are doing something about the test incorrectly or have gotten some of the reagents switched with others.

My first instinct is that the test was done wrong. All of us have grabbed the wrong bottle from time to time and wondered why the thing won't change color....

Second guess is massive dilution, which you have dismissed.

Third would be that it's falling out of suspension.....and starting to form scale. Has pH ever gone above 7.8 for any length of time?

Did the water go straight to blue, did it turn purple with floating lumps, or what?

What do you get for the calcium level when you test the fill water?

My first guess would be metal ion interference.

The issue has been resolved. It was due to some chemical problems. Thanks to everyone for your input.