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Thread: Muratic Acid/ Ph automation questions

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    Muratic Acid/ Ph automation questions

    Even after lowering TA, raising Ph, no aeration, etc... I am still having to add MA dailey. Ph rises .2-.3 per day. I was considering adding a Stenner for chlorine but am rethinking that MA is a bigger issue. I have read with interest the posts on the Simpool setup but availability is an issue. Stenner pump / timer would work as I cosistantly have to add 10 oz per day. Assuming dilution of the acid with water (ex 4 to 1), does the acid/water have to be mixed periodically? Wouldn't the acid sink to the bottom of the storage tank? Any other insight, especially on the Simpool would be appreciated!

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    Re: Muratic Acid/ Ph automation questions

    In this post it sounds like you just got new Pebblesheen. Since that likely involved some new plaster in between the rocks, you could still be experiencing a pH rise from that. Was the rate of your pH rise the same before the Pebblesheen, assuming your TA was low before as well (if not, then you can't compare)? Having to add acid every day is only something we hear about with new plaster. What's your TA level now?

    Acid and water are miscible meaning that the mix together thoroughly. The acid only sinks to the bottom if you add it quickly to water because the acid is more dense, but if you mix it up by stirring it with turbulent flow, then it will stay mixed. Muriatic Acid is 31.45% Hydrochloric Acid and stays mixed -- the acid does not settle to the bottom.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Muratic Acid/ Ph automation questions

    Unfortunately, I am having the exact same issue with the Pebblesheen as I did with the previous 14 yr old plaster! I almost switched back to pucks aftet the refinish but decided the CYA issue wasn't worth it. TA has gone from 110 after fill to 60 bbecause of the acid addition and ph rise has not slowed a bit. Target ph is 7.6-7.7. Switched from Walmart LQ to HASA LQ hoping that had something to do with it. I have no water features and have gone over all plumbing for possible air leaks. There are no bubbles indicating air in the system. Returns are pointed down and cleaner is adjusted to stay on the bottom. Most of my neighbors and co- workers rarely have to add acid!!! I have repeatedly read every ph related post in this forum to no avail. This is why I started researching an alternative to manual addition. I can miss a day or 2 with chlorine but the ph problem is far more critical because it rises so fast and so much. Borates seem to work great for some and do nothing for others, so I am not big on the idea right now. Still open to advice and suggestions!

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    Re: Muratic Acid/ Ph automation questions

    Mmmm... Well maybe the Walmart chlorinating liquid had a lot of excess lye in it, but it would have to be an awful lot to rise as much as you are seeing. I use Hasa in my pool and it does contribute to a rise but not by that much -- adding acid every week or two to move down 0.2 pH units (7.8 to 7.6 usually). With your TA down to 60 ppm after the fill, that would very much lower any carbon dioxide outgassing so I wonder what your source of rising pH is. Since you have a rising CH issue from evaporation and refill, if you do replace your water to dilute it over time then you could use pucks sparingly and get some pH lowering from that, but as you point out it will raise the CYA if you don't have water dilution.

    The borates would slow down the rate of pH rise, but wouldn't change the total amount of acid that would need to be added. It's a pH buffer, but it wouldn't change total acid amounts unless you had low-level algae growth that it helped control so that it lowered chlorine consumption. What's your daily FC consumption like? Is it around 2 ppm FC per day?

    You had mentioned your neighbors and co-workers before, but I thought they were using Trichlor pucks/tabs in which case they'd have the opposite problem and might need to use pH Up to keep the pH (and TA) from dropping too much. Do you know the pH and TA of your fill water (you can always test it)?
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Muratic Acid/ Ph automation questions

    Chem Geek,

    I recall that recently you stated, in another thread, that since the TA was going down along with the MA additions to lower pH. That the cause was not the plaster curing, it was now from another source.

    So that sounded to me like TA doesn't go down with the addition of MA being added to control rising pH when in the presence of curing plaster.
    Somehow the excess calcium releasing from the plaster keeps the MA from dropping TA as it normally would.
    Once the curing process is complete, then TA will go down with MA additions for lowering pH.

    Is that correct?
    Thanks for reading... - Tony
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    Re: Muratic Acid/ Ph automation questions

    He replaced the water so the TA there now was from the fill water. I don't know if the earlier TA was dropping or not. You are right with your description that any pH rise from initial plaster curing would have the TA remain stable when acid was added to maintain the pH. If the TA drops over time from acid addition when one is trying to keep the pH stable, then that means there is carbon dioxide outgassing.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Muratic Acid/ Ph automation questions

    OK, chlorine use is consistantly 2 per day, so adding 27 oz of 12.5% per day. CYA is between 25-30. Starting off lower in case I tried using pucks for a while. Should be cooling off soon which will probably reduce CL consumption even more. Make-up water is at 7.6/110. Have tried no acid addition for 2 days and it climbed to 8.0. Did not let it go further for any warranty issues with the finish. The frustrating part is that others on this forum are having the same issue and with all the very knowledgable people here, we haven't found an explaination. Some say that some pools just require more acid than others. I am okay with that, would just love to know why!

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