Acid Bath


Well-known member
Jun 20, 2013
Huffman Tx
I am building a koi pond black plaster is in and full of water . Koi people tell me to take the ph down to 6.0 for 1 month , The idea is to get the plaster to leach out . I think lime that makes the plaster pools run high ph for the 1st year.. make any sense ? input welcomed


LifeTime Supporter
TFP Expert
Jun 7, 2011
Midland TX
Yes, the constituents in plaster can cause the pH to rise in the first year. How well 6.0 for one month will do I can't say, but it won't be good for the plaster long term. Will it likely be fine? Probably, but it may get blotchy looking...hard to say what will happen. Just curious, I assume this is prior to adding the Koi?


LifeTime Supporter
TFP Guide
May 22, 2013
Hudson, WI
Depending on the expense and finish of the pond you might want to get the advise of a pool builder rather than Koi people. I know it's common practice to add a lot of acid to a fresh plaster job but I'd rather be taking advise from someone who builds ponds or pools so I know that 6.0 figure won't damage or fade the surface or color.

Do you have any pictures of the pond ??