Muriatic Acid versus granular acid

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
diddlyD

Re: Muriatic Acid versus granular acid

Postby diddlyD » Tue 15 Aug, 2017 18:52

Mr. DARTH DOUGY, I was ever so pleased to find your well detailed explanation on this subject mainly as it pertains on how to effectively lower PH "without" lowering TA that otherwise would utimatley results in a YoYo cycle effect that's senceless. I can attest to the fact that "Dry Acid" did not lower my TA only my PH and I was done. in fact, my TA actually had a very slight rise 10ppm. My PH has remained stable since for several days now. :) I would not recommend using Muriatic Acid as the ideal way to lower PH alone. Although Dry Acid costs more than Muriatic Acid you won't spend as much on chemicals in the long run as you won't endure the lowered TA and ultimately spike in PH again and have to add more chemicals on this endless cycle. IMHO, focus on keeping PH balanced as the priority and then TA should be easier to maintain.


diddlyD

Re: Muriatic Acid versus granular acid

Postby diddlyD » Tue 15 Aug, 2017 19:44

diddlyD wrote:Mr. DARTH DOUGY, I was ever so pleased to find your well detailed explanation on this subject mainly as it pertains on how to effectively lower PH "without" lowering TA that otherwise would utimatley results in a YoYo cycle effect that's senceless. I can attest to the fact that "Dry Acid" did not lower my TA only my PH and I was done. in fact, my TA actually had a very slight rise 10ppm. My PH has remained stable since for several days now. :) I would not recommend using Muriatic Acid as the ideal way to lower PH alone. Although Dry Acid costs more than Muriatic Acid you won't spend as much on chemicals in the long run as you won't endure the lowered TA and ultimately spike in PH again and have to add more chemicals on this endless cycle. IMHO, focus on keeping PH balanced as the priority and then TA should be easier to maintain.


I would like to make a final comment: Although my experience started with my TA on the very low end of the scale at 70ppm while my PH was too high, after adding Dry Acid it resulted in a slight "increase" to my TA now at 80ppm, which was fine; on the other hand, someone else has reported their experience with Dry Acid to lower their PH also lowered their TA "BUT" the difference was their TA started out on the other extreme with very high TA. So in conclusion, I believe TA is self adjusting in response to the PH changing not directly due to direct effect from the Dry Acid, so if the TA on the high side prior to adding acid it can be lowered and just the opposite can see an increase in TA.
Denniswiseman
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Re: Muriatic Acid versus granular acid

Postby Denniswiseman » Fri 18 Aug, 2017 17:39

Use these chemicals to balance your water
Liquid chlorine (sodium hypochlorite or plain bleach)
Muriatic acid (hydrochloric acid) to lower pH and TA
Bicarbonate of soda to raise TA
Aeration will raise pH only
Soda ash will raise pH and TA

This is proven and used by thousands of pool users check out www.troublefreepool.com
DittlyD
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Re: Muriatic Acid versus granular acid

Postby DittlyD » Sun 08 Oct, 2017 21:23

I read the above posts and don't have that same experience at all with using dry acid to the most part. The dry acid (PH down) I use is also 95% sodium Bisulfate. My TA does not or barely moves when adding "dry" acid to lower PH from 8 to 7.6 or 7.4 which usually takes about 1 1/2 cups according to the Taylor test kit Reference Manual (I highly recommend using). Today for example, PH was 7.8 not quite 8 and I added enough acid to bring it down to 7.4....TA did not change at all, still at 80. But when my PH got real high 8+ one time, I did see a rise in TA to about 90-100 and it did adjust down with the PH but I also added a lot more Acid to get the PH down to 7.4 that time. So maybe the difference here is how high the PH has to get to effect TA changes up and down when using higher doses of dry acid required to adjust the high PH down.

I just sprinkle the acid into circulating pool water a little at a time that's it (wearing protective gear of course) dissolves immediately. I use liquid chlorine in a feeder that dispenses into the pool water based on the pump running at night and adjusting PH "down" goes hand in hand with using liquid chlorine as the sanitizer; SWG I hear are even worse when it comes to high PH issues. So now what I'm hearing here is if my TA were higher than it is, my ph might be more stable, but I'm not sure what "stable" exactly means, a day; a week or never having to adjust the PH again? Maybe I already have stable. I thought I read somewhere that keeping TA on the low side stabilizes PH better. I do realize TA is a buffer to PH but is it better lower or higher; I'm at the low end of the OK range with 80 right now (I read getting it down to even 70 would be better for PH stabilization).

I'm currently adding PH down once to twice a week depending on when I add fill water (aeration). I see to many minuses for using Muriatic Acid mainly because it has very caustic fumes which most people pour right into the pool water that is so strong if not careful can stain the pool plaster (I don't have a diving pool with 12 ft deep areas) along with the instability of both PH and TA to save a perceived dollar doesn't pass the test for me. I also have not had to add any shock treatments but my water is not exposed to high levels of contaminates either. I hope another posted view is well excepted!
Denniswiseman
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Re: Muriatic Acid versus granular acid

Postby Denniswiseman » Mon 09 Oct, 2017 02:27

If you are currently reducing your pH up to twice a week then you may be aerating your pool water (fountain, infinity edge, waterfall or other aeration) Failing that your TA is to high, keep reducing it untill your pH stabilises
Each pool is different and the recommended levels suggested by the industry aren't always relevant to individual pools
Such as Chlorine / CYA Chart when the industry standard is 2-3ppm
DittlyD
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Re: Muriatic Acid versus granular acid

Postby DittlyD » Sat 27 Apr, 2019 16:44

I just did this with my pool so I can speak from practical experience. My TA was high compared to what it usually is I'm assuming to be from the city water which I test (ph 7.8 TA 130). I have been constantly fighting high PH 8+ and adding acid almost daily to get it back down to 7.8 and going through a lot of acid (no water features, no rain, no swimmers, just the pump running at night circulating the water and adding small amounts of diluted liquid chlorine via a feeder that's it). Everything I have read on websites says the remedy to stabilize PH is to drastically reduce PH with acid to around 7.0-7.2 in order to force TA to adjust down. I use dry acid, so I added the dry acid with pool pump circulating and waited about an hour and tested ph again, it came down from 8+ to 7.8 TA stayed the same, I repeated the same procedure and again Ph came down some more but TA stayed the same and so on until I got down to 7.2 and still TA didn't budge, until I turned off the pump and let it sit. TA has now lowered 30ppm although PH rose some too? So not sure if i have stabilized my PH as I read would be the result from this procedure; time will tell. At the moment my PH is 7.6 and TA is 100 which seems ideal according to pool calculators. So if I understand correctly, if I still have PH swings upward daily, then I should do this procedure again and lower TA further until I get a PH lock. The only thing is some people say the higher the TA you stabilize PH, so which is it very confusing? My previous post my TA was only 80 and I was having high PH problems this time it started at 130 and still having constant high ph issues. I wondered if maybe it's the liquid chlorine I read is the cause of high ph but other people seem to be able to control their PH and use the same unstablized liquid chlorine?
Teapot
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Re: Muriatic Acid versus granular acid

Postby Teapot » Sat 27 Apr, 2019 17:22

Not a lot of time to write a full reply tonight.
Yes with a high TA your pH will stabilise (buffered) unfortunately this is at pH of around 8.3!

Does that matter? Not if you have CYA in the water.

My pool being vinyl lined TA is not important but my local water has a TA of around 280, my pool I run at a TA of 40 and haven't added any pH minus products for 2 years, my pH dosing pump is disconnected. Same for many of my customers.

More tomorrow.
DittlyD
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My Pool: My pool is in AZ, 10,500 gal plaster play pool with cartridge filter, VS pump, off-line Liquid Chlorine feeder, auto vac sys., use Chemical test kit, dry acid for ph control.

Re: Muriatic Acid versus granular acid

Postby DittlyD » Sat 27 Apr, 2019 17:32

I will wait to hear more because your remarks are confusing. How do you get your TA to 40 then if your adding city water with TA at 280? Why is there these contradictions to lower TA to stabilize and you have the opposite position it needs to be High yet your pool TA is extremely low at 40 and so your not adding PH down (acid)???
DittlyD
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Posts: 4
Joined: Tue 15 Aug, 2017 15:07
My Pool: My pool is in AZ, 10,500 gal plaster play pool with cartridge filter, VS pump, off-line Liquid Chlorine feeder, auto vac sys., use Chemical test kit, dry acid for ph control.

Re: Muriatic Acid versus granular acid

Postby DittlyD » Sat 27 Apr, 2019 18:00

Here's some info that shed's light on the whole high PH never ending battling issue:

Pool pH is Always High:

The most common reason for a consistently high pH level in pools is using liquid chlorine, or a saltwater system as the primary sanitizer. Sodium hydroxide is produced, with a pH of around 13. New pool plaster or pebble finishes will also raise pH in pools, for about a year.

I use HASA Chlorine 12.5% which is high level of sodium hydroxide compared with most other brands on the market. Although, it is diluted in the feeder when it is dispensed via the pool pump about 4ppm during the night to reach about 7ppm to start the day (AZ) and so it's still at least 3ppm by evening when it will be used. My CYA is 50ppm which is in the OK range.

BTW, My CYA dropped after I had let my pool chlorine level get down to 0ppm (unintentionally, just ran out of chlorine), honestly. This occurred twice and both times it resulted in lowered CYA levels. It went from 90 to 50!!! No features, no one using the pool, no kids. No lie.
Teapot
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Re: Muriatic Acid versus granular acid

Postby Teapot » Sun 28 Apr, 2019 08:32

Hi DittlyD,
If you read the chemgeek posts early on the thread you'll get some idea.
chem geek wrote:The reason for rising pH has to do with the Total Alkalinity (TA) being too high since a higher TA means the pool is more over-carbonated. The outgassing of carbon dioxide makes the pH rise. Having more aeration or a lower pH has this happen faster.
Richard


I used to talk to Richard frequently and he is a better chemist than me, I experimented following discussions with Richard. I have a customer with really soft water and a supply of water with the TA at 27-30!! Being his pool person I immediately wanted to get the hardness and TA within the "industry" levels, it is a vinyl liner pool so no degradation of plaster or tile etc. I slept on the problem and also realised I had never added pH minus despite the owner having 2 children who splashed and bomb dived most of the time. We did need to add some pH plus because he was at the time using chlorine pucks.

I came home to my pool TA 280, again vinyl liner and set about lowering the pH and therefore the TA with muratic acid and aerating to raise the pH back up. This as you can imagine took a while but as a pool pro I had to run tests. At each stage of the TA coming down it took longer aeration sessions to raise the pH. I built an aeration tower with an air pump and a small amount of water (1/2 gallon) and commenced testing. With a TA of 240 the pH would climb to 8.3 within an hour. Repeating the test with a TA of 40 resulted in almost no change in pH after 24 hours of aeration (climb within 0.15). The tests were repeated 3 times each with the same result. Richard (Chemgeek) confirmed with a TA of 40 there is still 7 times more bicarbonate in the water than the air so slight off gassing will still occur but very slowly compared to water with a TA of 120 which has many many more times the bicarbonate dissolved into the water so off gassing and subsequent pH rise is inevitable, something the pool industry love $$$$.

The chemistry bit. Buffering water with TA, in our case bicarbonate will have the water buffer at a pH of 8.3, too high for our std pool operations so we fight it with an acid in a silly game the industry loves.

Running a low TA as I do means if you did need to adjust your pH downwards it would take a tiny fraction of the acid to do so as the water is not strongly buffered. Using pucks which have been manufactured to keep a balanced water based on the usual 120-180 TA could mean the puck's acidic content causing a sudden drop in the pH, not a problem if you are using sodium hypochlorite.

If people have tiled or plaster finish then the lower TA can make the water aggressive to these surfaces (the 120-180 TA came about as a way of ensuring this didn't happen by making the pH rise if anything went wrong rather than fall). The calcium saturation index shows us the easiest way to make the water less aggressive in this situation is to increase the pH slightly to offset the lower TA.

When I backwash my filters the water replacing it does raise my TA very slightly but not usually enough to worry about as the CYA is also a buffer but at a pH of 7 ish so helps to maintain in the range we want, the more CYA the bigger the pull (buffer) to pH7 the same as bicarbonate TA pulls the pH to 8.3, the higher the TA the stronger pull to pH 8.3 (buffer).
Teapot
Pool Industry Leader
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Joined: Tue 17 Oct, 2017 10:52
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Re: Muriatic Acid versus granular acid

Postby Teapot » Sun 28 Apr, 2019 09:20

To backup what I said earlier about pH not being important when CYA is present in the pool. Recent research has proved that the effect of CYA on the sanitising ability of chlorine is way more important than the pH. Having sufficient chlorine to overcome the CYA and continue to sanitise is more important than the pH. The pH can then be allowed to drift upwards to pH 8.3 provided sufficient free chlorine is available. Some flocculents/clarifyers will not however operate at such high pH levels. It does at least mean you don't have to struggle so much with pH especially if you reduce the TA.
Article- http://www.poolhelp.com/home/onbalance- ... -efficacy/

On to your CYA reduction, yes we have observed this happening before, it could be a bacteria that thrives on CYA as companies are marketing "enzyme" treatment to reduce CYA rather than draining down and replacing water. These solutions have had limited success but are pricey, you got it for free!! I have also reduced CYA levels down by oxidising the CYA with high doses of chlorine when draining wasn't an option.

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