High PH, low KH - how to fix?

[Charlottekoi]

Hey guys - question for you. My city tap water has a PH of over 9.3 but a KH of under 40. I thought that wasn’t possible, because I assumed if the PH was high, the KH would be high too. I now know to add baking soda or oyster shells to get the KH up (which stabilizes the PH) but won’t the baking soda actually raise the PH too?

I HAVE to add the baking soda because as you know the KH needs to be 100+. My pond PH is around 8.6 which seems a little high; so if I add baking soda to get the KH up, I don’t want to push my PH past 8.6! I’m confused here - any guidance would be helpful. thanks Charlottekoi

Ps hope everyone is staying sane while under lockdown!

 

[JRS]

My understanding is the baking soda will raise the KH while having a minimal effect on the pH. Stability is more important than your pH which is high but acceptable and this is your goal.

PH, KH And GH in Depth

There are questions about pH, KH, and GH posted on this forum nearly every day. In this thread, I will discuss what these mean and how they affect your pond. Please do not post comments directly in this thread. If you have any questions or comments, you may PM me or start a new thread and we...

www.koiphen.com

 

[Alice_Bee]

it may be gypsum raising your pH, because it isn't carbonate, the KH remains low. It won't show up on a College lab test unless you ask them to test for it. Do your plants die unless potted in dirt? I have never raised the kh with baking soda without first burning off the gypsum, which is easy to do but dangerous to fish, if you already have fish in the pond