Question on cooking rocks with muriatic acid

[MBVette]

I picked up some rock the other day from a member and I need to cook it b/c it has been out of the water and had all kinds of algae. So I went to the store and picked up a bottle of muriatic acid today, and plan to cook the rock this weekend.

 

Now I just want to make sure I dont mess up using this stuff and it has me a bit nervous since I have never used a chemical like this.

 

I plan on doing the cooking in 5 gallon buckets and I have some long rubber gloves to take the rock out.

 

So I will put the rock into the bucket, cover with water and then the bottle says use a 1/20 ratio of acid to water.

Then I will let it sit in the bucket an hour or two?

Take the rock out and can I reuse the same water/acid mix for more rock or should I get rid of the mix for every new batch?

 

Then I was told I can pour baking soda into the mixture to counter the acid and then I can basically pour it into the sewer?

 

Any advice on this would be very appreciated.

[Steve175]

Use gloves. Careful not to breath fumes. Try not to fill bucket more than half (water will bubble up when Muriatic is added to bucket). Replace water with each batch for consistent effect (acid will be variablt diluted as H+ used up). I have always poured directly down drain while running water without ill effect, but sodium bicarbonate would make sense. Not sure how long to soak rock or what to expect: I use muriatic all the time, but only to clean (tanks, skimmer, PH, etc)

[AlanM]

Here is where I did it:

 

http://wamas.org/forums/topic/51680-getting-in-to-reef-tank/#entry450963

 

and here is a separate topic where Origami was schooling me on the acid chemistry:

 

http://wamas.org/forums/topic/53473-using-vinegar-vs-muriatic-acid-to-clean-aquarium/

 

After I cooked the rocks I soaked them in bleach for a while and then soaked in RO/DI and rinsed over a few days. I was told that I could have used tap for the rinses. It's brilliant white now.

[MBVette]

Thanks. So do about a 1:10 ratio, leave it sit until it stops bubbling and then dump out and start again.

 

So after this you did a rinse in bleach for how long? And then just soaked it in water for a few days and your rock was good to go?

[AlanM]

I dont have it in a tank, so I cant guarantee that it is good to go, but i did leave it in RO/DI for a week after I did three days of soaking in tap and dumping the water out each night, and I didnt get any nitrate or phosphate on the red sea pro tests I did.

[MBVette]

And I assume there is no smell of the acid left. As long as it tests 0 I think thats all I need. Im going to have this running empty for a few months while cycle it anyway

[AlanM]

No smell, here are some pics of the current state dry. I dont have before, but it had been a heavy algae filled tank that had then been set out on the back porch in a dry trashcan for two years.

 

 

[sachabballi reef]

dang that is the whitest rock I may have ever seen!!!

[AlanM]

The underparts were also covered in the little white sponges or tubeworms or whatever those things are, and they all came off too.

[swimmatte]

Muriatic (Hydrocloric) Acid is some nasty stuff. We use it in my industry on a daily basis and boy have I seen some serious accidents. With that said, as long as proper precautions are taken it's not a big deal. The biggest thing is, DO NOT MIX IT WITH BLEACH, or any similar chlorine type of product. You will certainly have a visit to the ER in your plans.

[wade]

Also, always add acid to water, not the reverse. It can boil up and burn you if you add the water to a pool of acid.

 

Hydrochloric acid has no real odor. Any odor is decaying organic matter. That said, the rock will dissolve as well as any organics left on its surface if you leave it too long.

 

As for neutralizing the acid before you dump it, yes! If you have old piping in your house (copper or iron) running acids through it is not recommended. Use baking soda and you wind up with salty water.

[swimmatte]

Also, always add acid to water, not the reverse. It can boil up and burn you if you add the water to a pool of acid.

 

Hydrochloric acid has no real odor. Any odor is decaying organic matter. That said, the rock will dissolve as well as any organics left on its surface if you leave it too long.

 

As for neutralizing the acid before you dump it, yes! If you have old piping in your house (copper or iron) running acids through it is not recommended. Use baking soda and you wind up with salty water.

 

Correct. When we use MA to clean with, we are actually taking off a very thin layer of the surface rather than "cleaning" it.

[AlanM]

My rock got noticeably more fragile after I put it through the acid bath. Lots of nice pores, though. 8)

 

It was much less acidic after the rocks sat in it for an hour. The calcium carbonate in the rock neutralizes it just like sodium bicarbonate does. That's what's happening when it's doing all that foaming.

 

As wade and others have said, even though you can buy it in gallon jugs at Lowes or HD, this stuff is no joke. When we use acid of this strength at work we do it in a specifically designated and certified fume hood with special gloves and detailed procedures for working with strong acids and neutralizing the remnants. We don't go dumping it at arms length into Brute trash cans full of water while holding our breath with our eyes closed, neutralizing it with a Costco bag of baking soda, and tipping it over to hose the goo off the deck (all of which, I did).