What are the practical limits to MA additions?

[SunnyOptimism]

Hi All

General muriatic acid (31.45%) addition question - is there a practical limit to how much acid you can add to pool within a given time period? I seem to remember reading somewhere on another site that you can't down adjust your pH too quickly with a large acid addition without risking damage to your pool.

For example, let's say you use my 17k gallon pool and I'm at a pH of 7.8 and I'd really like to be down at 7.0 to reduce my TA through acid/aeration process (assume my other parameters like FC/CC/CYA are all good). Based on previous acid demand tests and PoolMath, I'd be adding something like 2 quarts + 2 cups of 31.45% MA. Obviously one would add that much acid very slowly in front of a return and perhaps do a good brushing to ensure proper agitation.

Can I really add that much acid to the pool and/or practically drop the pH that far without seeing some serious pH rebound or possibly damaging walls and SWG's? Is it better to dilute and broadcast around the pool or break up the additions with some wait time in between? Just trying to get a feel for a good methodology

 

[kcindc]

According to pool school it is okay. Just make sure that you pour very slowly in front of the return with the pump running.

"Muriatic acid should be added to the pool by pouring slowly in front of a return jet with the pump running. You should pour slowly enough that pouring an entire jug takes more than two minutes. Leave the pump running for at least 30 minutes after adding muriatic acid."
http://www.troublefreepool.com/content/139-recommended-pool-chemicals

 

[jblizzle]

You can add as much acid as you need as long as you keep the pH in the 7s.

I am not sure where the pool store gets the idea they told me that you should never add more than a quart at a time ... with no knowledge of pool volume.

Just add the acid in front of the return jet and a quick brushing is good insurance.

 

[HouTex]

Focus on slowly. I got in the habit of pouring too quickly over the same return, but with my shallow pool (4.5 feet in the deep end) I eventually eroded a small hole in my plaster. About the size of a half dollar.

 

[JasonLion]

The key is to never lower PH below 7.0, keeping in mind that large PH changes tend to be more mistake prone than small PH changes. Generally for large PH changes you don't want to add more than 2/3rds of what PoolMath calculates, give it half an hour, test again, and adjust from there.

As long as you don't lower PH below 7.0, you can add lots and lots of acid at one time. Just remember to pour slowly in front of a return jet while the pump is running. Brushing is not required as long as the pump is running, and remains running for at least half an hour after the acid addition.

 

[SunnyOptimism]

Good points all around. I'm prob going to need to lower my TA soon (have some CYA issues to clear up first) so I'll need to do acid/aeration at some point. My pH is at 7.6 right now. So when I do my additions, I'll do a half add, mix, measure and adjust further if needed.

THANKS.


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