What Color Is Muriatic Acid Supposed To Be?

[rrgone]

Greetings!

I've been adding MA periodically to keep the pH from drifting up. When I opened the box of MA a few minutes ago I was shocked to see that both jugs were a deep yellow in color (no lie - looks like jugs of urine - ick!) This is KEM-TEK brand MA. I remember the MA I used previously being much more clear in color. I don't remember what brand I used previously. Do you think there's a chance I got a tainted batch?

Thanks for reading.

[rrgone]

Huh - nobody has a jug of muriatic acid that they can look at and tell me the color?

[chem geek]

It it near colorless to light yellow, depending on concentration, but typical Muriatic Acid is light yellow. If you had chlorine instead, it would be closer to green and you can tell the difference right away since Muriatic Acid does not smell like chlorine and is in some ways even more irritating (just use your hand to waft fumes from an open bottle towards your face and you should be able to smell what it is).

As for being a deep yellow, that does sound strange, but doesn't sound like chlorine. It may just be a more contaminated form of Muriatic Acid.

Your pool can still experience a rise in pH after adding acid if it is high in Total Alkalinity (TA) and/or has a source of aeration such as waterfalls, spillovers, fountains, showers and especially a saltwater chlorine generator (SWG) since that produces hydrogen gas bubbles that pull out lots of the carbon dioxide from the water and into the air and that causes the pH to rise (it's a myth that the reason SWG pools rise in pH is due to the added chlorine -- chlorine is alkaline/basic when added, but chlorine usage is acidic and exactly compensates so hypochlorite sources of chlorine as well as SWG-generated chlorine are essentially pH neutral).

Richard

[rrgone]

Thanks for your reply Richard. I'm sure it's not liquid chlorine - I shock with that so I have a few boxes of that here too. In fact I shocked last evening and the chlorine was a pale yellowish-green color. I'm convinced I got a box (two 1 gallon jugs) of tainted something. It's marked Muriatic Acid but I really don't want to open it or put it in my pool.

Thanks for reading.

[Tom]

Greetings!

I've been adding MA periodically to keep the pH from drifting up. When I opened the box of MA a few minutes ago I was shocked to see that both jugs were a deep yellow in color (no lie - looks like jugs of urine - ick!) This is KEM-TEK brand MA. I remember the MA I used previously being much more clear in color. I don't remember what brand I used previously. Do you think there's a chance I got a tainted batch?

Thanks for reading.

My father, a tinsmith, used to use concentrated muriatic acid as a flux for soldering galvanized iron; that acid was a deep yellow and it seems to me that the color deepened with age. It could be that your current batch is either more concentrated or older than your previous batch. Either way, it should work as expected (perhaps in lower doses if the concentration is different).

[rrgone]

Well if anyone is still interested I picked up a new box of muriatic acid yesterday. This new one came from Ace Hardware, the older box with yellow colored acid came from Home Depot. The new acid is nearly clear as described by chem geek. Interestingly, the new, clear MA is stronger than the yellow MA. The new MA is labeled 29% hydrogen chloride and the older MA is labeled 14.5% hydrogen chloride. Does that mean that the new MA is twice as strong as the old? I'm going to use the clear MA in my pool tonight to lower the pH.

I'm curious if anyone else has some of the yellow MA they have used?? I guess it's probably OK, just weaker?

If anyone is really curious I put up a couple of pictures here:

muriatic acid 1

muriatic acid 2

Thanks for reading.

[chem geek]

Yes, the newer MA is twice as strong as the old. It used to be that all Muriatic Acid for pools was 31.45% so the 29% is at least close to that. At some point, someone figured out to sell 15-16% MA at the same price and several users have reported that around the country so you really have to read the labels carefully. The main advantage to the lower concentration is that is should fume less so be less noxious -- it's probably the harshest chemical added to a pool.