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.
adain24
Pool Newbie
Pool Newbie
Posts: 1
Joined: Sat 25 Jul, 2009 04:46

Muriatic Acid versus granular acid

Postby adain24 » Sat 25 Jul, 2009 04:53

sounds so delicious! Thanks


-------------------------------------------
Nu-Pet Granular Greens


darryl2

Muriatic Acid versus granular acid

Postby darryl2 » Thu 10 Sep, 2009 12:22

I just poured 2/3's of a 1lb,6oz bottle of sodium bisulfate to to my above ground pool.It's measurements are 18'x26'x4'.A free water test at a store said my ph was high and chlorine low.And that was all.So I picked some up.I have yet to add chlorine.I have some tablets laying around for the pool,and a 2 1/2 gal container I was going to use for the well water.Did I do this right?
Guest

Muriatic Acid versus granular acid

Postby Guest » Sun 12 Dec, 2010 21:36

I have never heard of anyone recommending mixing chemicals (acid or otherwise) in a bucket of water before adding to the pool. I would not listen to this recommendation as it is BS.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Muriatic Acid versus granular acid

Postby chem geek » Mon 13 Dec, 2010 02:29

The only "bucket of water" reference was in the first post in this thread and that bucket was only being used to mix acid with water. So long as acid is added to the water and not the other way around, then diluting the acid in a bucket of water is OK, though not usually necessary since adding it slowly over a return flow usually provides enough mixing, especially if the pool side and bottom is lightly brushed in the area where it was added.

The part about Muriatic Acid and dry acid behaving differently in terms of TA is bunk, but diluting acid in a bucket of water isnt' a problem. I agree that one should generally not mix chemicals in a bucket (other than dilution with water in the bucket first).
Guest

Muriatic Acid versus granular acid

Postby Guest » Thu 11 Aug, 2011 19:03

Hi I just wanted to confirm that in my inground pool the muriatic acid did lower total alkalinity and I had to use Baking soda then back to acid , etc. When I use PH down I don't have the same problem. This year I didn't have to use baking soda once until I used muriatic acid. So the first explanation was accurate for me and not BS as stated.

Oh and PH always rises in my pool anyway I have a salt system but total alkalinity did not crash until muriatic acid was introduced.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Muriatic Acid versus granular acid

Postby chem geek » Thu 11 Aug, 2011 21:55

No, no, no. Why did you add baking soda? If you have a problem with rising pH, then you do NOT want to raise your TA back up higher. TA is a SOURCE of rising pH through carbon dioxide outgassing. The procedure for lowering TA is described in this post where you will notice that it is a combination of acid addition and aeration at lower pH. There is NO adding of baking soda to raise the TA, even if the TA is below 80 ppm. If your pH tends to rise, as is often the case for saltwater chlorine generator (SWCG) pools, then you want your TA to be lower. If you use 50 ppm Borates in the water, then you can have the TA even lower than 70 ppm because the borates provide additional pH buffering. If you have a plaster pool, you can have the CH be higher to compensate and should also target a pH such a 7.7 instead of 7.5.

The dry acid most certainly lowers the TA just as the Muriatic Acid does, but perhaps you didn't use as much dry acid. If you used too much Muriatic Acid then that would obviously lower the TA more, but outgassing of carbon dioxide would bring the pH up again eventually so the key is to lower the TA level and KEEP IT LOWER. You do NOT want to raise it by adding baking soda.

There are thousands of pool owners with SWCG systems who have significantly lowered the rate of pH rise in their pools and the amount of acid they need to add -- they did this through the combination of lower TA, higher CYA, and use of 50 ppm Borates as described in Water Balance for SWGs .
Alfonso

Muriatic Acid versus granular acid

Postby Alfonso » Tue 01 Jan, 2013 18:56

What is the chemistry involved in the action of sodium bisulfate to lower pH in a pool/spa?
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Muriatic Acid versus granular acid

Postby chem geek » Thu 03 Jan, 2013 11:01

NaHSO4 ---> Na+ + H+ + SO42-
Sodium Bisulfate ---> Sodium Ion + Hydrogen Ion + Sulfate Ion

The solid sodium bisulfate dissolves in water to release hydrogen ions and these lower the pH. You will notice that you get leftover sodium and sulfate ions as a result. Compare this against using Muriatic Acid which is usually 31.45% Hydrochloric Acid which is

H+ + Cl-
Hydrogen Ion + Chloride Ion

So with Muriatic Acid, you don't get sulfates and only get chloride ion (i.e. a component of sodium chloride table salt). If you use a lot of acid and build up sulfates to a high level, then this can become damaging to plaster surfaces.
Guest

Muriatic Acid versus granular acid

Postby Guest » Sun 12 Jan, 2014 23:07

I would not worry about TA being at 150 as long as your pH is in a good range 7.2-7.6 then all good. You will find keeping your pH in a good range with the addition of acid (dry or liquid) will bring down the TA naturally so having high TA is usually a good thing. One less thing you have to balance in your pool.

Return to “pH & Total Alkalinity”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 0 guests