Muriatic Acid loosing strength over time?

[lovingHDTV]

I built myself an acid injection system for MA, but think I may be loosing the strength of the MA as it sits in the storage tank waiting to be injected into the pool.

I dilute my MA 50-50 with water and store it in a 5 gallon container that has a 1/8" barbed fitting that is used as an air vent. I can't let the pump create a vacuum in the tank or it wont work as the pick up tube would collapse on itself.

I don't have specific numbers to compare, but it appears that the acid solution is not working as well over time as pouring the full strength acid directly into the pool. Previously I thought I was using about 1 gallon of acid per month, so I setup my pump to inject this amount into the pool and it does this quite well. I have noticed that I still have to add about 1 gallon of acid per month in addition to what the pump is delivering.

This could be that I was not correct in my assumption previously because I never logged my acid usage. I just put it in and periodically reduced TA after adding fill water. But I was wondering, could I be loosing MA do to evaporation or some other means?

How do the "commercial" tanks handle the venting of the tank so that they do not form a vacuum?

thanks,
dave

 

[duraleigh]

The chem guys will be along soon but I believe muriatic stays at the strength at which you purchase it.......for a very long time.

I will learn something new if that turns out to be incorrect.

 

[JasonLion]

Higher concentrations evaporate very quickly, but by the time you dilute it the evaporation rate is far lower. If it isn't obviously fuming it should last a good while in a container with only a small hole in it.

 

[heikejohn]

Just read in another thread, that the MA from Home Depot is only half the strenght as the stuff at the pool store. Something like only 14%.
What is the strenght of your MA?

 

[lovingHDTV]

Just read in another thread, that the MA from Home Depot is only half the strenght as the stuff at the pool store. Something like only 14%.
What is the strenght of your MA?

I get all my MA from the pool store at 31.45% I think.

dave

 

[sbagdon]

I can definitely say that MA losses strength, as bottles stored over the winter don't have the same "punch" as those bought that year. It's not measured, yet it appears measurable. I'm not sure what chemical reaction would cause the loss of strength (apply a base to an acid?), yet I plan on it happening (if there's any MA left over at the end of the season, and it's going to be stored until the following season).

 

[lovingHDTV]

If this happens would it be like chlorine, where the volume of the acid does not change, but the chemical make up does?

Hope that makes sense.

 

[chem geek]

Muriatic Acid shouldn't be losing its strength. That's not my experience with it and normally pure acids and bases have a very long shelf life. I don't have an explanation for your experience with it unless your TA or borates level increased which would require more acid to be used to lower the pH level.

 

[DBfan187]

AFAIK it has infinite shelf life

 

[lovingHDTV]

Muriatic Acid shouldn't be losing its strength. That's not my experience with it and normally pure acids and bases have a very long shelf life. I don't have an explanation for your experience with it unless your TA or borates level increased which would require more acid to be used to lower the pH level.

This is good to know. I'll chalk it up as not fully tracking all the acid I used prior to my setup. I just wanted to be sure that my setup did not have something fundamentally wrong. If nothing else, this process has let me know that I use much more acid than I thought.

Wish my fill water did not have a TA=200 . . .