What is the best/safest way to lower PH from above 9

[studiovette]

I tested my water today with my pond master kit since I had 1 fatality last week and another fish is sick. My levels were perfect with exception of PH which seems to be over 9.0. So what is the best and safest way to lower then stabilize it. My tap water is around 6.5. It's been raining all week. My pond is aprox 1000 gallons and haven't had this issue before. I know some use oyster shells
Thanks

 

[Fishylove]

Oyster shells will work, but over time. Wow over 9? Temp of the water will effect things too. I don't believe I've seen one that high in a pond. You'll need to bring it down slowly for sure. I have some ideas but, I think there are others on here more experienced with Ph, so I pass to them.
Good luck

 

[j.w]

You could do a very slow water change as your tap water is quite low and would fix it eventually. Do it at just a trickle tho.............water going in, water coming out at the same time. You don't want to shock the fish. I always thought that oyster shells once put into the pond just kept your ph at the same level. Did not know it lowered ph.

 

[JohnHuff]

Um, I think oyster shells release carbonate and increases pH. You want to decrease pH and make it more acidic. I googled and it said use 1/4 cup of vinegar for every 500g. My suggestion, add 1/4 cup, test and adjust.

 

[Fishylove]

Which is why I leave this to the experts

 

[studiovette]

Yea I'm gonna go with the vinegar. Addy also suggested it and it seems like a reasonable and easy way to try to lower it. Once I have it in the target range I will start to use some oyster shells.

 

[Mucky_Waters]

Do you have any idea why the ph in your pond is so high when your tap water, which I assume you are filling your pond with, is 6.5?
Actually you asked for the "best and safest way" to lower and stabilize the PH of your pond water, and doing so with chemical (in this case vinegar) is neither safe, nor stable. Rapid PH swings can be just as harmful to fish as rapid temperature changes.
Your best and safest way is to do a J.W. suggested, slow water changes. Just set up a slow drip from your hose and let it drip for a week or so. If you have any chlorine in your tap water, and get a slow drip going, the chlorine will neutralize before it builds up to any harmful or even detectable level.

Drip,,,,, drip,,,,,,, drip....

 

[studiovette]

I am going to retest this morning. I tested around noon yesterday which seems to be the worst time to test. Also when I tested the PH with a liquid test it showed up as solid blue which means 9.0 or above . When I tested with my pool dip stick the PH was in the 8.0 range. I might also take a sample of my water to be tested to make sure I am getting an accurate measure.
I agree after thinking about it the drip method is more logical and safer

 

[addy1]

I struggle to keep mine in the 7 range, crushed oyster shells, have made my pond water harder. It took a season for the ph to settle at 7.6 Might be the plants, the bog, algae, age who knows, but it is working............whew!

 

[Grillmark55]

I'm new to "ponding" and to the forum but thought that I'd throw my hat in the ring on this. We have a pond that is about 1200 gallons and has been open about 8 weeks. (Well, maybe more like 4 weeks; we had a heavy rain - over 4" one night- that washed a bunch of clay into the pond. It wouldn't clear so we drained 100% and refilled... but that's another story). Anyway all of our pond's levels (ammonia, nitrite and phosphate) are under control (all 0 ppm) except for pH. I tested it a few days ago late in the afternoon and it was over 9. Retested it before sunrise the next morning and it was down around 7.5. We have about 50% of the surface covered with plants but quite a bit of algae. We have 10 fish all under 4" long. Can't see more than about 6" or 8" deep so it's bad but not horrible. I did a lot of research about lowering the pH and the consensus seemed to be don't do ANYTHING to try to adjust the pH until the algae is under control. I don't know if that is your situation, but I did read quite a bit on NOT dumping in chemicals to raise or lower pH until other factors have been addressed.