Is it OK to use liquid acid in an inground, vinyl pool?

rugadog

Member
May 23, 2009
20
USA
I took a water sample to Leslie's to have them analyze the CYA level just to make sure the reading of 80-100 I keep getting was correct. The teenager working the other afternoon confirmed it was about 90. Then the sales pitch started, he said everything else in the water looked OK except the ph, which he said was high, about 8.0. This is the same level I measured. After having the water checked at Leslie's I was planning on going to Home Depot and picking up some acid to drop the ph and picking up pvc parts to to build an aerator (thanks to Ashbourne).

I told the kid I already had the acid and what my plan was. He said, "Liquid acid in a vinyl pool? Are you sure you want to do that??". I asked why and he said liquid acid isn't good for vinyl pools.

So, is the kid right???
 

duraleigh

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Apr 1, 2007
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So, is the kid right???
Well, he's batting .500 (which is not bad for a young, lead-off hitter and really excellent for Leslie's :lol: :lol: )

He apparently did a good job on the CYA test but he struck out on the acid question. Hundreds, if not thousands of people on this forum use acid everyday to lower the pH in their pools.
 

woodyp

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Apr 17, 2010
10,371
East Texas
You DO know to pour it in SLOWLY in front of a return, right? Most folks don't add over a quart at a particular time, and leave the pump running for 3 or 4 hours after you add.
 

rsharp

Well-known member
Jun 12, 2010
129
on my bottle of acid it said to always dilute the acid first. i dont know if this holds true for pool use but i always pre dilute it in a bucket of water. (wearing safety goggles).... i havnt had any problems.
 

geekgranny

LifeTime Supporter
Aug 20, 2009
1,358
North Central Texas
I always dilute first even in my plaster pool. Acid into water always; not the other way around. I saw a video last year where someone put dye in MA in poured it into a pool. It sank almost immediately and then ran down towards the drain. Made an impression on me. So I dilute and then pour in front of returns. I use a 2-4 gallon plastic bucket filled with water about 2/3 and then pour part of the measured acid in water. Redo as needed to get proper amount into pool. Also make sure the handle on the bucket is intact and not aged from sun. I like the buckets have plastic handles so no problem if I splash acid on them.

In spa I turn jets on. They say not to turn bubbler on because of splashes but I turn it on too and have eye protection on. BTW..... I've used MA for most of my adult life for all sorts of projects. Even acid washed my pool several times. I've never gotten any eye splashes because of eye protection. I was at a friends house the other day. Her pool needed a little acid. I was in a great hurry to leave so poured small amount standing on top of 4' sheer decent. No eye protection. I got my first eye splash but it was mostly water. So wear that eye protection.

gg=alice
 

mitch08

Well-known member
Jun 30, 2008
400
Suffolk County, NY
Quick question on this topic.

Will liquid acid bring down my TA? I want to drop the PH a bit (maybe .2 or so) but keep the TA where it is since my pools been extremely consistant with the TA at 70.

Thanks.
 

Melt In The Sun

TFP Expert
LifeTime Supporter
Oct 29, 2009
3,899
Tucson, AZ
Addition of any kind of acid will lower your TA. Typically though, it takes a bunch of acid to make TA move significantly. See the "effects of adding chemicals" section at the bottom of the Pool Calculator.

I wouldn't worry about it; if TA gets low enough that it causes issues, you can very easily bump it up with baking soda.
 

svenpup

LifeTime Supporter
Nov 18, 2009
835
Sacramento, CA
mitch08 said:
...Will liquid acid bring down my TA?...
Yes. So will any acid. You can use the "effects of adding chemicals" section of the pool calculator to see the specifics.
Why are you worried about TA changing? It isn't a big deal and is easy enough to bring back up. Many of us who use liquid chlorine or SWCG like to keep TA low to offset pH rise anyway. Are you worried about CSI?
 

mitch08

Well-known member
Jun 30, 2008
400
Suffolk County, NY
Thanks. The thing is, it becomes a never ending cycle.

Sure the TA is easy to bring back up. But then the PH goes back up with it.
So Ill add acid which brings my PH down but then I need to bring the TA back up...

:hammer: :hammer:

My TA is 70 and my PH is 7.8.

Everything is fine I guess, but I would really like to bring my PH to 7.5.
But when my TA goes below 70 my PH gets more volatile.
 

Melt In The Sun

TFP Expert
LifeTime Supporter
Oct 29, 2009
3,899
Tucson, AZ
Yes, it always is a never ending cycle, but if you bump your TA up to about 90, you'll have quite a bit of time before it drifts back down.
 

svenpup

LifeTime Supporter
Nov 18, 2009
835
Sacramento, CA
Have you tried leaving it at 7.8 and seeing what happens?

Up until recently I would immediately bring my pH down to 7.5 every time it got up to 7.8. I have heard that pH likes to sit at around 7.8 with borates so I am doing an experiment now to determine how long it takes to get up to 8.0.

The impression I get from the experts here is that a little bit of "hands off" philosophy can save frustration as far as pH is concerned (within reason of course) as opposed to constantly fighting it. I have (had?) a tendency to see a recommended range and decide I must be right in the middle. As I get more experience I realize that the edges (or even outside) those ranges can be OK as long as you have a reason and understand the effects. (Zen and the art of pool maintenance)
 

mitch08

Well-known member
Jun 30, 2008
400
Suffolk County, NY
Its actually been 7.8 for about 3 weeks. But a few people complained their eyes were hurting a bit lately so I figured I would try dropping it to 7.5. I like the idea of bringing the TA to 90 but then Im afraid Ill be adding acid all the time. Right now its extremely stable although just a bit high.

Sorry... Didnt mean to hijack the thread but it was on topic :)
 

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