Question about Alkalinity

Julie46128

Member
Jun 16, 2019
10
Indiana
Hi ! So just filled the pool on Sunday with a water truck using city water. It’s a 16x28 above ground oval 52” deep. Brand new pool and first pool for me. After some great advice from this forum, I purchased stabilizer, bleach and muriatic acid. My water numbers with no chemicals were
ALk 300
PH 8.0
CH 240
I added stabilizer, bleach and muriatic acid slowly several times.
I have only been able to get my ALk down to 220 but my PH hit a low 7.0 so I have stopped adding muriatic acid and am now aerating. I have put in two gallons of the muriatic acid before stopping.
MY BIG QUESTION IS
My water is crystal clear and all other numbers are perfect. I received my water from the city water supply. If it came delivered to me with a Alkalinity Of 300, how can that be so bad? I mean this is the city drinking water so I would think it would be safe to swim in! I mean my PH was at 7.4 perfect along with everything else measuring perfect and my water crystal clear but my ALK was still at 250. Is ALK really all that important if all other numbers are perfect?
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
Hi ! So just filled the pool on Sunday with a water truck using city water. It’s a 16x28 above ground oval 52” deep. Brand new pool and first pool for me. After some great advice from this forum, I purchased stabilizer, bleach and muriatic acid. My water numbers with no chemicals were
ALk 300
PH 8.0
CH 240
I added stabilizer, bleach and muriatic acid slowly several times.
I have only been able to get my ALk down to 220 but my PH hit a low 7.0 so I have stopped adding muriatic acid and am now aerating. I have put in two gallons of the muriatic acid before stopping.
MY BIG QUESTION IS
My water is crystal clear and all other numbers are perfect. I received my water from the city water supply. If it came delivered to me with a Alkalinity Of 300, how can that be so bad? I mean this is the city drinking water so I would think it would be safe to swim in! I mean my PH was at 7.4 perfect along with everything else measuring perfect and my water crystal clear but my ALK was still at 250. Is ALK really all that important if all other numbers are perfect?
Alkalinity isn't a critical measurement. The range on the old poolmath (I use an old flip phone, don't ask me about the app) says suggested range 50-90+. Are you at 90+? Yes. Good. Leave it. All the high TA will do is cause pH to rise faster. And each time you lower pH, you lower TA some, too. It'll come down over time. Your CH is low enough that you're not in any immediate danger of scale formation. Leave the TA alone.
 
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Julie46128

Member
Jun 16, 2019
10
Indiana
Alkalinity isn't a critical measurement. The range on the old poolmath (I use an old flip phone, don't ask me about the app) says suggested range 50-90+. Are you at 90+? Yes. Good. Leave it. All the high TA will do is cause pH to rise faster. And each time you lower pH, you lower TA some, too. It'll come down over time. Your CH is low enough that you're not in any immediate danger of scale formation. Leave the TA alone.
Thank you so much! I really appreciate you taking the time to reply!!
 

Fast7

Well-known member
Aug 8, 2018
180
Plainfield, IL
Hi Julie
When you plan to add anything to your pool, it's best to use PoolMath calculator first to find out how much product to add.
Based on that it looks like 2 gallons of muriatic acid (31.45%) would lower your pH to less than 6.7
You have to be careful with that.
If you can, please add your signature with your pool details, equipment and test kit.
 

Julie46128

Member
Jun 16, 2019
10
Indiana
Okay tested again this morning after aerating and PH is back to perfect 7.4
ALk is still at 250
CH is at 240
FC is at 4.0
TC is at 4.0
CYA is at 20
Pool is crystal clear
so I am forgetting about the high ALK and leaving alone. I will test daily and if my PH raises I will add a little acid at a time and hopefully ALK can come down over time. Does anybody see anything wrong with this approach. Pretty excited about the way my water and numbers look less than three days after fill.
 
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IceShadow

Gold Supporter
Jun 8, 2019
1,072
Milwaukee, WI
That's pretty much what I see recommended. Might not need to test daily, but you'll get a feel for that as you go - if it's changing slower, you can cut back on the amount of testing for pH. :)