CH levels going up and down

[Delph]

I have been several times to my pool dealer to test my water this last month, and every time, the CH levels come back different. Like completely different. one day it will be at 180, and next time at 350, and everything in between...When it was at 350, I was told to partially drain my spa and refill. I did not, and I'm glad I didn't because it was down to 200 a few days later, without me doing anything to it...

Does the CH levels fluctuate like that or are these tests not accurate at all?

I should say, same thing happened with the TA levels. One day it was too high, i didn't do anything and the next time it was too low..

[MPurcell]

Pool store testing is notoriously inaccurate. Your best bet is to purchase a good quality test kit and do the testing yourself. That's what I do. Your experience proves the veracity of this statement. If I were you, I wouldn't rely on pool store testing, or even use it at all. Pool stores stay in business by selling products, most of which you do not need, and some of which can cause serious problems in your spa. Calcium Hardness should not vary too much over time unless you are using a product with calcium in it, like calcium hypochlorite. But it wouldn't go up and down. Total alkalinity can drift slowly up and down as you adjust your pH up and down, but it wouldn't be radical differences.

Oh, and test strip type testing is also rather inaccurate and unreliable. You need to invest in a good test kit with reagents, such as the Taylor K-2106 if you are using bromine, or the K-2006 if you are using chlorine.

 

[Delph]

Thank you. I just purchased the Taylor K 2106 and hopefully that will make things easier!

[MPurcell]

Once you get the kit, it's a good idea to log your results and keep notes about when and what you add to the water so you can get a clear picture of your results.