View Full Version : Reducing Ph with muriatic acid?

02-20-2006, 12:48 PM
I heard this and was shocked at first, but then I calmed down. Īn a LFS around here I was commenting how my tank ph stands around 8 always (actually, 7.8 as my new more precise test revealed yecterday) and the clerk told me they used to maintain the ph of their discus tank using small doses of muriatic (clorhidric) acid. This sounds a little too drastic to me, and would like to hear opinions about it.

In another store, I was told to use apple vinegar, and the owner claimed it would not start swinging the ph, instead it will remain stable.

I've always been against changing the pH using chemichal products, but this idea has somehow digged into my head.


02-20-2006, 1:15 PM
I've used vinegar and baking soda to lower/raise the pH. The tap pH is like 6.8 so I've given up on it and leave it alone now. FWIW, i never had any problems with either, and they were both effective.

02-22-2006, 7:28 AM
Thats pool acid. Same stuff they use in swimming pools to maintain the PH for humans. I used to manage a pool supply store in FL. In practice it works fine for us, but we dont have gills, so I am not sure about using it for fish. If your LFS uses it for the discus tank, then it must work just fine I suppose.

02-22-2006, 7:57 AM
I have hard water and have used tons of muratic acid in my pool...
the thing that happens is a rebound effect. It will initially lower it, and then it will rebound back up. I have seen the comment made that you are better leaving them at a higher ph and have it stable than to monkey around with it and subject the fish to swingsd in ph, unless you plan to breed them.

02-22-2006, 7:59 AM
Muratic acid is powerful stuff. Unable to clean some grease spots from my driveway with conventional cleaners, I tried it. Scrubbing vigorously with an old broom, the driveway soon sparkled. I set the broom and old sneakers I wore aside to dry. The next time I saw them nothing remained except the stump of the broom and the rubber soles of the shoes.

I too am concerned about the water. The local utility publishes their measurements which I found spot-on in the summer but not now. Their (and my) pH was greater than 8 then but now it is more like 7. I use Seachem 7.0 which worked all summer but now I see the tank pH slowly crawling down. I'm experimenting with several jugs of water outside the tank to try to understand the chemistry. Wish I hadn't slept through the class so many years ago.

02-22-2006, 8:22 AM
Any acid will do the trick, but the stronger the acid is the less chance for error you will have. Muriatic is strong stuff and is used in pools becuase there is a lot of water. Fish tanks are smaller and therefore anythign over a few drops will probably be way too much, also you will want to use it in a mixing tank which can be tricky if you have to prepare large amounts of water.

A high pH/ hardness can easily be diluted using distilled water, though a stable pH is more important than a perfect one.

02-22-2006, 8:47 AM
i did that years ago--i did it because i took care of pools and thought it would do the rick in a tank. It did. As was mentioned you need a separate mixing container/tank. You need gloves and eye protection. Muriatic is dangerous stuff if not handled properly.

The muriatic acid was in the 70's though. Unless you are thinking of keeping and/or breeding some very specific species why bother. water with a pH of 7.8 or higher should be fine for most of the store bought fish of today. And, as was also already said, you will have to deal with the ups and downs of pH level.

What type of fish are you keeping.

If the species really require it why not use RO water and fortify it with tap water to get the buffers and electolytes back into it. That would be much more stable than trying to bring pH down by any method.

02-22-2006, 9:47 AM
Thnaks a lot for your responses. I myself have always told paople to avoid playing with the Ph and have also seen the problem with the ph swinging up and down for adding chemichals.

I use muriatic acid to clean the sink and toilet from time to time. Once I put a lot undilluted acid in the shower ceramic ans the porcelain between the tiles just dissapeared. I know how powerful it is.

I have stingrays in that tank, and though they seem to be doing fine, I've seen some fungal infection in them constantly. The only water parameter thet is not right for them is the pH, which is recommended at 6.8 and my 8 is too high.

02-22-2006, 12:53 PM
Muriatic Acid is a dilute Hydrochloric Acid. My professor in college once spilled some of this stuff on the couter without knowing it. She then leaned against it and it cut a slit right across her pants. No injury but the acid ate away the fabric much like a knife cutting away at the fabric. I've seen people spill a drop of this stuff on their shirts and find later that they had holes burnt into the shirt. Pretty corrosive stuff. Diluted in the fish tank, it would be quite harmless but it does make the water pretty unstable.

02-22-2006, 12:56 PM
Any idea of the effect of apple or any other natural vinegar in the water?

02-22-2006, 1:09 PM
I've heard of using distiled vinigar to lower ph as well. The only thing I've actually used is different forms of blackwater extract (humic acid, and tannins). The problem with that is that you have to use a TON of it in order to eat up the buffering capacity of your water before the ph will drop. By that time I got to the ph I was shooting for (6.5) my water was not just tea colored, but more like weak coffee colored. I could barely see my fish.