Muriatic Acid Useful Life or Expiration Date

[swimer]

How long does Muriatic Acid last in its original gallon bottle? I have some that must be at least 3 yrs. old. Thanks.

[PoolDoc]

Forever! It does not go bad.

BUT . . . and this is a HUGE BUTT . . . the bottles do go bad, if exposed to sunlight. And, a brittle old bottle can crack open without warning, spilling acid everywhere.

[Upgraded membership; moved thread]

[JimK]

That reminds me, I have a couple bottles of MA that are years old (stored outside in a plastic, covered garbage can). Since adjusting TA and adding borates years ago, pH has been rock solid, so I haven’t had to add acid.

This thread reminds me I need to contact the city to find out how to properly dispose it.

[PoolDoc]

That could be problematic. HAZMAT fees can be horrendous.

Here are some alternatives:

• Give it to a brick or masonry contractor.
• Give it to pool contractor
• Add it to 5 gallons of water in a plastic garbage can; add "washing soda" till it stops foaming; pour it down the tub. It's just salty water at that point!

[JimK]

That could be problematic. HAZMAT fees can be horrendous.

Here are some alternatives:

• Give it to a brick or masonry contractor.
• Give it to pool contractor
• Add it to 5 gallons of water in a plastic garbage can; add "washing soda" till it stops foaming; pour it down the tub. It's just salty water at that point!

Interesting. I like the third option. Is there a certain amount of water I should use for each gallon of MA? I’m not sure the exact amount I still have...will have to look tomorrow.

Thanks.

[PoolDoc]

2 gallons of water to 1 gallon of acid will stop the 'fuming' or release of hydrogen chloride gas. This is important, since sodium carbonate (washing soda) + hydrochloric acid (muriatic acid) => carbon dioxide + salt. The carbon dioxide is what will be bubbling up . . . but if the acid is still concentrated will facilitate the release of acid gas fumes.

[JimK]

2 gallons of water to 1 gallon of acid will stop the 'fuming' or release of hydrogen chloride gas. This is important, since sodium carbonate (washing soda) + hydrochloric acid (muriatic acid) => carbon dioxide + salt. The carbon dioxide is what will be bubbling up . . . but if the acid is still concentrated will facilitate the release of acid gas fumes.

Thanks. I’ll give it a try.

[JimK]

Thanks for the info, Ben.

I did as you suggested. I had just over two gallons of MA left. It took just under 4 boxes of washing soda (55 oz each I believe) until it stopped reacting with the diluted acid.

Btw, I visited 4 stores before finding one that had washing soda. ��

I have a few boxes left. I assume I can use this in the future in the pool to raise pH if needed? I usually have to raise pH at spring opening, and then it stays rock solid all season.

[PoolDoc]

In our area, Walmart has washing soda and borax in stock more consistently than others.

FYI "washing soda" = sodium carbonate = 'pH Up' aka 'pH increaser' aka pH+', etc. Contrary to some pool store villains, it's not almost the same, it's exactly the same as what's sold as pH+ and so on.

And it too, will keep indefinitely, though it will turn into white lumps if it gets damp.

[JimK]

That’s good to know. I’ll keep the rest inside (climate controlled) to minimize clumping.

I normally use borax to raise pH, but I used the last I had at opening. It was really clumped up from being stored in the shed.

I’m glad to be rid of that old MA. I haven’t needed it in years.