Why did my pH just drop suddenly?

[8ightiesfan]

I've been taking care of our pool for almost 3 years now, pH has always remained very steady at 7.6 and I very rarely add any acid.

Recently I tested and pH was the usual 7.6, but CYA was extremely low (hadn't tested CYA in a while over winter) so I added dry stabilizer in 3 doses, 500g, 500g, 1kg over a 1 week period. CYA increased to 80. I also added 20kg of salt to top it up.

Yesterday I did a test and pH tested very low around 7.0, this has never happened before, could this be caused by something I did or we also have had a lot of rain recently, could a particular rain event cause this? I've increased it slightly via aeration to 7.2, but will look at adding some soda ash to bring it back up to 7.6

Just trying to understand if this is something that I caused?

Thanks

 

[pjt]

I added dry stabilizer

This will lower your pH.

Use PoolMath --> "Effects of Adding" --> "Dry Stabilizer".

pH tested very low

Clear Choice labs test kit

Possible testing uncertainty. Do you have access to a Taylor pH test (maybe a neighbor or friend)?

will look at adding some soda ash

Just keep aerating and the pH will rise. No need to add chemicals.

Consider bumping up your CH to help your CSI. Your pH will probably stabilize in the high 7s, which will also help your CSI. You need to have higher FC if your CYA is 80.

 

[8ightiesfan]

This will lower your pH.

Use PoolMath --> "Effects of Adding" -- "Dry Stabilizer".



Possible testing uncertainty. Do you have access to a Taylor pH test (maybe a neighbor or friend)?


Just keep aerating and the pH will rise. No need to add chemicals.

Consider bumping up your CH to help your CSI. Your pH will probably stabilize in the high 7s, which will also help your CSI. You need to have higher FC if your CYA is 80.

Thanks for the reply, I do have another older drop test kit that I also use to check pH, this also showed pH at 7.0

Thanks for pointing out the effect of adding in the app, I have never looked at this before. adding 2kg of dry stabilizer shows a drop in pH of 0.5, this definitely explains it!

Yes, I have some Calcium Chloride at the ready which I was about to add when I realized the low pH

Thanks for your help.