Adding Too Much Muriatic Acid -Raise my TA?

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D

dfiletti

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LifeTime Supporter
Jun 12, 2008
76
Thornton, PA
Folks-

I've been having to add at least .5 - .75 gallons of muriatic acid per day for the last few weeks to keep my pH in check. Seems like a lot to me. If I skip a day, my pH goes over 8! +/_ two weeks ago, my TA was 130, now it's 60, and I have not been aerating. I'm guessing that T/A loss is from the incessant muriatic acid -please confirm?

I saw a note on the pool calculator that indicates that with a SWG, a good T/A target is 60-80. But I also know that it's a new pool (1 year old) and that, plus SWG has a tendency to raise pH, thereby needing stabilization -true?

Anyway I'm thinking of adding 5.8 lbs of baking soda to bring the TA up (which will yet again raise my pH, but c'est la vie...) I'm buying muriatic acid by the 5 gallon jug these days.... I'd appreciate thoughts as to a good target level for T/A

Any other thoughts as to why my pH keeps raising so much more dramatically than last summer? -Last summer I had to add muriatic acid maybe once every three weeks, and even then, not a lot -course my T/A was hovering around 110...

My numbers:
FC: 3.5
CC: .5
TC: 4
pH: 7.6 (at the moment)
T/A: 60
CH: 440
CYA: 30 (I know this need to go up to +/- 60)
Temp: 78
Salt: 3300

Any and all help would be appreciated.

Thanks,

Dan
 
dfiletti said:
Folks-

I've been having to add at least .5 - .75 gallons of muriatic acid per day for the last few weeks to keep my pH in check. Seems like a lot to me. If I skip a day, my pH goes over 8! +/_ two weeks ago, my TA was 130, now it's 60, and I have not been aerating. I'm guessing that T/A loss is from the incessant muriatic acid -please confirm?

Acid will lower both PH and TA. Aeration only raises PH.

I saw a note on the pool calculator that indicates that with a SWG, a good T/A target is 60-80. But I also know that it's a new pool (1 year old) and that, plus SWG has a tendency to raise pH, thereby needing stabilization -true?

By new pool, do you mean a new gunite/plaster pool? A plaster pool will have the tendency to raise both PH and TA while it is curing. However, you shouldn't have much of that anymore. Generally, a low TA will help keep the PH down so you don't want to raise TA.

Anyway I'm thinking of adding 5.8 lbs of baking soda to bring the TA up (which will yet again raise my pH, but c'est la vie...) I'm buying muriatic acid by the 5 gallon jug these days.... I'd appreciate thoughts as to a good target level for T/A

This would be counter productive. I would leave the TA alone.

Any other thoughts as to why my pH keeps raising so much more dramatically than last summer? -Last summer I had to add muriatic acid maybe once every three weeks, and even then, not a lot -course my T/A was hovering around 110...

My numbers:
FC: 3.5
CC: .5
TC: 4
pH: 7.6 (at the moment)
T/A: 60
CH: 440
CYA: 30 (I know this need to go up to +/- 60)
Temp: 78
Salt: 3300

Any and all help would be appreciated.

Thanks,

Dan
Click to expand...

First, get the CYA to 80 ppm. This will help reduce the amount of on time for the SWG and reduce the PH rise. Also, how high does the PH actually get? I wouldn’t bother lowering it until it hits 7.8.

Another factor could be your fill water. Test that as well to see if you have low TA or high PH.
 
Mark-

Thanks for the reply. Not sure how high exactly my scale only goes to 8.0. Anecdotaly seeing what .5, and 1 gallon does, over time, it seems as though if I skip a day, it get's to 8.5ish. For instants, I skipped Monday after the pH was 7.6 on Sunday afternoon. Measuring it on Tuesday, the there was clearly no orange in the color so it was 8+. I added 1.5 gallons last night and it read 7.2 this am -mustard/ yellow. When I got home it was what I consider a perfect orange: 7.6.

Wow, so low CYA can have a effect pH swings -I thought that was the the job of TA -learn something new every day.

Thanks,

Dan
 
dfiletti said:
Wow, so low CYA can have a effect pH swings -I thought that was the the job of TA -learn something new every day.
Click to expand...
Not directly. The CYA buffers chlorine; chlorine is generated by the SWG; the SWG operation increases pH. So a higher CYA will buffer more chlorine, i.e. you lose less to sunlight, therefore the SWG doesn't need to run as much, therefore the pH doesn't go up as fast.

If you don't have a SWG then the CYA level doesn't really affect pH.
--paulr
 
dfiletti said:
Wow, so low CYA can have a effect pH swings -I thought that was the the job of TA -learn something new every day.
Click to expand...

Not directly, but increasing CYA lets you decrease the percentage output on your SWG. This will help keep the pH from drifting up. :goodjob: Adding borates will introduce a second buffer that will help stabilize the pH as well.
 
Reporting back/ Updating.

I added 8 lbs of CYA 10 days ago, and I measured CYA this AM and it still shows low -~45 (up from 30 before the 8 lbs). Hmmm.
a reading of 50 would have been generous as I could still see most of the black dot @ waist level. Not the easiest test to interpret, but it definitely was not the 60 the pool calculator indicated it would be. I added 4 more lbs this morning and will measure later in the week.

Latest numbers:

FC: 3.25
CC: 0
TC: 3.25
pH: 7.8
TA: 70
CH: 460
CYA: 45
Temp: 82
Salt: 3300
Filter Pressure: 22
SWG Setting: 15%
Motor Run Time: 12 Hours/ day
Pressure Side Cleaner Run Time: 4 Hours/ Day

I am still adding ~ 1/2 gallon MA per day (actually 1 gallon every other day, but it has not changed after treating with 8lb of CYA) It just feels excessive.

Any additional thoughts?

Thanks,

Dan
 
dfiletti said:
Reporting back/ Updating.

I added 8 lbs of CYA 10 days ago, and I measured CYA this AM and it still shows low -~45 (up from 30 before the 8 lbs). Hmmm.
a reading of 50 would have been generous as I could still see most of the black dot @ waist level. Not the easiest test to interpret, but it definitely was not the 60 the pool calculator indicated it would be. I added 4 more lbs this morning and will measure later in the week.

Latest numbers:

FC: 3.25
CC: 0
TC: 3.25
pH: 7.8
TA: 70
CH: 460
CYA: 45
Temp: 82
Salt: 3300
Filter Pressure: 22
SWG Setting: 15%
Motor Run Time: 12 Hours/ day
Pressure Side Cleaner Run Time: 4 Hours/ Day

I am still adding ~ 1/2 gallon MA per day (actually 1 gallon every other day, but it has not changed after treating with 8lb of CYA) It just feels excessive.

Any additional thoughts?

Thanks,

Dan
Click to expand...


PS. I only added 4 lbs (which the pool calculator shows should take to me 60) out of concerns of overshooting. I'll add 3 more lbs if my new CYA test @ ~60 in a week.
 

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bring you CYA up to 80 ppm and then adjust the SWG down to maintain the correct FC level.
BTW, both the pool calculator and my own hand calculations say that 6 lbs should have raised your 24k gal pool from 30 ppm CYA to 60 ppm so there is something wrong here.
You have a free form pool and it seems the gallonage you are using is underdosing. I would suspect that your pool is bigger than you think. Free form pools are a problem. What shape is it? There are some freeform shapes that are fairly easy to compute but others need to have the volume determined chemically.
 
I'm fairly certain that the 24K is ~ accurate. It was what the pool companies' CAD calculated, and was backed up by the amount that the water delivery delivered +/- 1000 gallons. Hmmm.

Any possibility I got weak CYA? Bought it from my local Carlton pool store. It reads: "Chlorine Stabilizer" (100% CYA on the ingredients).

Well, 4lbs more should have an effect. I'm thinking I'll bring it up incrementally and continue to add MA 3-4 times a week.

I'll work on getting my CYA up to 70 or 80 and report back on MA usage once that has been done.

Thanks for the input.

Dan
 
PaulR said:
800 sq ft at average 4' deep is 24k gallons... if the deep end is reasonable size or deeper than 6' this is probably a lowball estimate.
--paulr
Click to expand...

The deep end is 7' deep and there is no dive well so it's, I gather, fairly small as a percentage of the rest of the pool +/- 20% maybe before the ramp to the shallow end starts. As for shape, it's very irregular. I custom designed it with the pool builder using the "Mountain Lake" template as a starting point if that rings any bells with anyone. As I said though, I'm fairly sure the gallonage is +/- accurate.

Thanks,

Dan
 
If you want to go to the trouble this method of chemically determining the volume of a pool works if you do it carefully!
http://www.poolhelp.com/ChemicallyDeriv ... olumes.pdf
The only way CYA could be 'weak' is if it is cut with something. If it says 100% cyanuric acid and it's not then we have a truth in packaging problem!
I do know that some companies are selling CYA that is not 100% cyanuric acid but has fillers in it. However, this is marked on the label.
 
I'm wondering if my application method of CYA has anything to with my anomalous results? For the 8lbs, I added maybe 3lbs into each skimmer. and then two lbs into an extra canister filter I had installed that comes off the main drain. It has a mesh bag that can be emptied from the deck sort of like it's a skimmer basket with a lid -and I put it in the mesh bag. Anyway, with +/- 6lbs going thought the skimmer baskets/ pump basket into the DE filter, could the effect of the CYA have been mitigated in some way? I did not back wash. I seemed to remeber that this was the correct way to add CYA, but maybe not?

Grasping for straws, but thought I'd ask.

Thanks again.

Dan
 
Just a follow-up, I got confirmation yesterday that my pool DOES have considerably more water in it than I thought. The pool company came out yesterday and drained and re-polished my Hydrazzo. The water truck driver indicated he put 27,000 gallons in and I had to run the hose for a few hours to get it up to my mid-tile line (was down about 3" and that did not justify another whole truck). So I'm figuring I have a +/- 28,000 gallon pool, as apposed to a 24,000 gallon one.

So I'm starting over on chems -new water, and I'm out of CYA reagent -just reordered some. In the meantime, can anyone offer input on how much CYA drinking water has in it typically? Can I assume it's near zero usually? I'd like to get my CYA up ASAP. I'll post out numbers later.

Thanks,

Dan
 

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