Muriatic (Hydrochloric) acid and lowering pH

[cschwaderer]

Well after 6+ years of keeping Discus and every winter around this time having stressed out fish, I finally talked to our water department lab and talked with them about what changes this time of year.

They said that our water gets much harder this time of year, so they raise the pH to precipitate out much of the calcium and other solids from the water. They said the pH measures between 9.2 (normally) to 9.8 (now - this time of year). Now when I do my pH tests with my master test liquid kit, I normally get around 7.4-7.6 in my aging container. But right now I'm getting about 8.6 so either my pH liquid testing is inaccurate or somehow the tap water lowers in pH somewhere between the water plant and my house.

Anyway, the water lab guy (and some old articles on this message board) mentioned lowering the pH using muriatic acid, so I got some Sunnyside Muriatic acid which said 31.45% Hydrochloric acid and 68.55% "inert ingredients". When I called the company they said the inert ingredients is water, but it might have a few ppm trace contaminents since its commercial grade.

The water lab guy said a few drops should lower the pH, but I'm wondering about the future stability of the pH once I do that - will it stay at the new pH indefinitely? Will the water be more unstable once I do that? Does anyone have any experience doing this? Should I consider another method?

Every year my Discus stress out with their water changes and stop breeding for a few months, so I suppose I shouldn't just keep doing nothing. When I measure the pH at about 7.6 I figured that should be ok as long as I've got clean tanks, etc, but maybe I should be shooting for something lower since I'm spawning discus as well?

Thanks for any info,
Curt

[Moon]

I have rock hard well water with a ph 8.2 and conductivity of 350. This water is very stable and fine for growing out young ones. For breeding adults and wc discus I use RO water. The product water from the RO system comes out with a ph 7.2. I've tried Muriatic acid to lower the ph. I tried this in a holding barrel with a few drops (about 10) per 30g of water. The ph crashed to aout 3.2 almost immediately and the conductivity increased back to 350.
The conclusion is that the buffering capacityof RO product water is not capable of handling the introduction of acid even in small quantities. Caution is needed in the addition of acids to RO water. Now I use peat moss. It does not reduce the ph by much but a much safer method imo.

[ShinShin]

Curt,

I used muratic acid to lower my pH for about a year for a tank of wild discus. I would fill a 75gal with fresh water and several large air stones for 24hrs. I would lower the 100gal tank that housed the discus to 25% full, then pump the 75gal into the 100gal. . The pH never varied for me. I do have naturally low conductivity in my tap, ~55mS. I don't know if your water's parameters would keep your pH stable after adding the acid.

Mat

[MostlyDiscus]

I agree with Larry here, I have tried a few different acids over the past year and now only use Muriatic acid solution with no problems in water stability. If you try to adjust your RO/WC water first it would be too difficult to control. I use a cole parmer ph controller(15yrs old now) and a doping jug(old gallon pickle jar) to control the tank water itself. My ph will change a bit during large water changes but I position the probe down stream from the doping tube. I would dilute the doping jar a bit till you get a feel for the right amount of acid per gallon. hope that helps.

Ed

[cschwaderer]

Thanks so much guys for your informative responses. It's just fantastic to have a resource like this to get information from.

So I think the consensus is that if you attempt to lower the pH of water that is mixed with RO, the water is quite unstable and I'll be succeptible to pH crashes if I attempt to use muriatic acid. The interesting thing is with my 4-stage RO unit, I measure the pH of that water at about 6.4. One of the posters said his RO water is at 7.2. My brain says that distilled water should of course be 7.0. Any explanations? The TDS of my RO water is 6.

My water TDS is about 180ppm this time of year and increases to about 210ppm in the summertime.

Right now I have a 40 gallon garbage can I store the RO in and a 160 gallon storage container with a sump and piping to all my tanks. When I use RO, I do the bucket-brigade thing - fill the tank with storage water and add buckets of RO until the desired % is reached at the same time.

Seems like my options are:
1. Go ahead and mix RO into my storage tank. This would be better for my breeding tanks, but worse for my grow out tanks.
2. Use the muriatic acid on my aged tap water storage container and just use that. I'm intrigued by Ed's ph monitoring system and doping jug. Ed, is there anywhere I can get a more detailed description on how you set one of these systems up?

won't adding muriatic acid increase the TDS of the water? I've heard that Discus pairs do best in low ppm water.

Another question - my water is about 180ppm at this time of year and the last water change stressed one of my pairs, so I added some aquarium salt to see if that would help. That made the ppm about 450. Then they spawned in this water yesterday. If the ppm is that high, but because of adding salt, will that have an adverse affect on fertilization?

Thanks,
Curt

[ShinShin]

I just happen to have great water here out of the tap so I never had to know alot about water chemistry. One would think that R/O and distilled water ought to be neutral, but it is slightly acidic. If I had water questions, I would shoot RandalB a PM and ask him.

Mat