Alk too high

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Pool_Kid

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Oct 14, 2015
30
AZ
my 7x7 spa has water that i keep nice and clear, balanced for the most part, but my test strips always show alk way high. chlorine and ph are good, over time chlorine goes down and ph rises, so i balance back with chlorine powder and dry acid, but how can i get alk to come down? i do have a nature-2 installed too.

and as good info, my water is about 80% soft water and 20% of very hard water.
 
Probably the best place for us to start in an effort to assist with your question is a full set of test results from your TF-100 or Taylor K-2006. This will help tremendously. If you only have test strips, you're simply not receiving the accurate results you need. Typically, acid is all you need to lower TA, but even that is done only when there is a clear reason to lower TA (i.e. an elevated TA makes the pH rise). Also, be careful with the Nature 2 products as they have been known to add metals to the water which can cause staining. Typically, chlorine (regular bleach) is the only sanitizer you really need. Do a search on this site for Nature 2 and you'll see many such discussions.

We look forward to any test results you can post and hope to help you further. Have a nice day.
 
i can get full test results from local pool supply place.
the n2 was recommended to help sanitize and to lower amount of chlorine. i bought a 3pk, i swap it out every ~6mo. i do use a cap's (~tblsp) worth of Metal Free every week. i use Chlor Brite Granular for sanitizer.

as for acid bringing down ta, i use the acid to bring ph down but this does not seem to change ta at all, well, at least not on my test strips.
 
I see. Well, honestly you'll find here at TFP we don't place a lot of faith on pool store testing primarily because of inconsistencies in their results. What ends-up happening is the pool owner adds products not really needed based on those bad results or simply because the store needs to sell a product. Your best solution would be to obtain one of the recommended test kits from the TF-100 link below in my sig. Because N2 adds metal, you are being forced to add a metal free sequesrant periodically when you really shouldn't need to - again ... money and added chemicals not really needed. I believe the Clor Brite is a non-stabilizing product, but you still need a basic amount of stabilizer in your water, so you may want to watch for that. And remember, chlorine is a fundamental (pure) sanitizing agent. We emphasize the use of regular household bleach for that very reason. Anyone who tries to say you should use less chlorine in lieu of something else is probably just trying to sell you their product. :) Happens all the time.

But to your original question, acid is the key to lowering TA. New fill water will raise it though. With your own test kit, you could test that source water to see if it's high in your area. Hope some of this helps, have a nice "Valley of the Sun" kind of day.
 
We hesitate here to give suggestions based off of test strips. They simply are not accurate enough. I would second the advice above on getting a good kit such as the tf 100 or the Taylor k2600. Also you can find acid cheaper at Home Depot or Lowes. I grab the 2 gallon box from the garden section at Home Depot for less than $5. Make sure it's Muriatic acid.
 
Defgufman said:
We hesitate here to give suggestions based off of test strips. They simply are not accurate enough. I would second the advice above on getting a good kit such as the tf 100 or the Taylor k2600. Also you can find acid cheaper at Home Depot or Lowes. I grab the 2 gallon box from the garden section at Home Depot for less than $5. Make sure it's Muriatic acid.
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yes, i have to get myself a kit. i am using Dry Acid (Sodium Bisulfate). i also have Muriatic acid. i am using about 1/2fl.oz. of dry about once/wk to control the ph. how much Muriatic (and what % of Muriatic) would be the equiv? from some online data, if ph is over 7.6 i should add ~0.5fl.oz of Muriatic to 400gal (my spa is ~386 gal). but, i wont switch until i get a test kit. i will get the k2006 kit from wal mart in just a few min. what tests are needed from this kit, just chlor/alk/ph/ca ? or are there others that will help to know whats going on?

i guess the dry acid just isnt doing what i need it to:

Many customers come to us with the problem of their pool water pH constantly rising on them. While there are many reasons for the pH to continuously rise, one of the most common can be due to the use of muriatic acid to lower the pH. It is important that you understand what muriatic acid does when added to your pool water and why this can result in the pH constantly rising on you.

First, you need to understand what Total Alkalinity is and how it affects the pH of your pool water. By definition Total Alkalinity is a measurement of water's ability for the pH to change. In other words, the higher the Total Alkalinity, the harder it is for the pH to change. It is important that you maintain the Total Alkalinity between 80-120 PPM. (This can vary somewhat depending on local and source water.)

Muriatic acid is a dilute form of hydrochloric acid which is a very strong acid. Even diluted, muriatic acid is still a very strong acid. When you add muriatic acid to your pool (even if you have diluted it more in a bucket of water), not only do you lower the pH of your water but you also lower the Total Alkalinity of the water. With the Total Alkalinity lowered, it is now easier for the pH to rise again (this can be due to many reasons), so if you add more muriatic acid to lower the pH, you also lower the Total Alkalinity even more, thereby making it even easier for the pH to go up again. As you can see, it is a vicious circle you are in.

How do you lower the pH without lowering the Total Alkalinity? You should use a dry acid (pH lower, pH minus, etc.) mixed into a bucket of water first, then poured around the pool. Dry acid is a much milder acid than muriatic acid and when diluted in water will have almost no effect on the Total Alkalinity of the water while lowering the pH. This will allow you to maintain the Total Alkalinity level, which will make it more difficult for the pH to change, thereby reducing your pH fluctuation.

Why does the dry acid not reduce the Total Alkalinity like muriatic acid does? Because for the Total Alkalinity to go down, you must get the pH below 5.5 in the water. Adding muriatic acid (because it is so strong) lowers the pH of the water. When you pour it to below 5.5, the chemical reaction that lowers Total Alkalinity now takes place. Adding a dry acid (a much milder acid) especially when diluted in a bucket of water does not lower the pH in that area to below 5.5. Therefore the chemical reaction that lowers Total Alkalinity does not take place.
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Defgufman said:
If TA drops too much just add Baking Soda
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OP's issue is that the TA will not come down.

Pool_Kid said:
my 7x7 spa has water that i keep nice and clear, balanced for the most part, but my test strips always show alk way high. chlorine and ph are good, over time chlorine goes down and ph rises, so i balance back with chlorine powder and dry acid, but how can i get alk to come down? i do have a nature-2 installed too.

and as good info, my water is about 80% soft water and 20% of very hard water.
Click to expand...

Dom
 

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ok, that quote came off another pool info site. in words it explains that dry acid will not reduce ta like muriatic will. is that correct?

and, my local chemicals/pool supplies store gives info that is confusing. he tells me that dry acid and muriatic are the same thing.... i guess he means they are both acids.

he also tells me to let ph climb near 8+ and then use like a 2oz dose of dry acid and this will pull down the ph and ta. this does not make sense to me. i suspect the dry acid is not the right chemical to pull down ta in my spa water, maybe i use muriatic when ph is high and that will drag both down, then attempt to keep ph in the middle using the dry ??

i went to wal mart to get the k2006 kit (as seen on their website) but xmas has taken over everything where pool supplies would be. geez, not even 31Oct yet and xmas has taken over.

i'll get the test kit 1st, get some #'s, and then go from there. but if you can explain why muriatic pulls ta down better than dry acid, i am all ears. thanks.
 
Any strong acid will reduce pH and TA, liquid or dry.

Also, the higher your TA the faster the pH will rise.

Have you you read the article in Pool School on how to lower your TA?

It explains how to use acid and aeration to correct your TA/pH balance.

There is some incorrect info in that post you quoted. Higher TA levels generally do not help stabilize pH rise, instead it is usually the opposite with higher TA levels actually causing the pH to rise quicker. Also, any strong acid added to the pool will effect both pH and TA, dry or otherwise.

[edit] it is better to let your pH climb a bit to 7.8 or so, then add enough acid to get to 7.2. You need the larger additions of acid to get your TA moving downwards. Try to stay in the 7.2-7.8 range while doing this. [/edit]

Dom
 
i read that page. the quote i gave is backwards then, high alk will allow ph to swing easily. some data i find on ph and alk for marine tanks, they test vinegar to lower ph, and then muriatic acid, both lower ph but vinegar did little on alk while muriatic acid lowered both ph and alk.

so, it seems not all acids will lower ph and alk. i need explanation on this.
 
I have an attached spa to our pool and every year in the spring I start with a fresh fill of water with a TA of 130ppm. It takes me 5 months of adding MA it to get it down to a TA of 70ppm with adjusting the ph from 8 down to 7.2 each time. We have our pool winterized now with the spa still open. It takes only 2 ounces of MA to go from ph 8ish down to 7.3ppm for our 900 gallon spa. Once I hit 50ppm of TA I add 50ppm of boric acid which helps settle down the ph. I'm going to add the boric acid this weekend since I'm almost at the 50ppm TA.
 
If you have a high TA in your fill you probably will just be adding the MA as needed to keep the PH in check. Be careful with the MA because it is nasty stuff compared to the powder that you have been using. It will stain decks and don't get a wiff of it when you add it to the water.
 
Pool_Kid said:
i read that page. the quote i gave is backwards then, high alk will allow ph to swing easily. some data i find on ph and alk for marine tanks, they test vinegar to lower ph, and then muriatic acid, both lower ph but vinegar did little on alk while muriatic acid lowered both ph and alk.

so, it seems not all acids will lower ph and alk. i need explanation on this.
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Vinegar is not a strong acid, and is not something we recommend to be put in a swimming pool.

The recommended acid to be used in a residential swimming pool will address your issues with TA. I don't know why you insist that some acids will not effect TA. All true acids will effect alkalinity, weaker acids (like vinager) will not effect it as much.

Hopefully Chem Geek will be by to properly explain the chemistry involved.

Dom
 
so, i measured it with test strip now (had to order k2006 from amzon, local places did not have).
ph/alk (ppm)
by color, it was ~7.8/240 (maybe higher on alk side, seemed to be the darkest color the strip would go and match the label, etc)
i added ~1.25 fl.oz of ma (the 35% stuff, it's called "contractor ma", not sure if pool ma is a lesser or greater % than that)

i let circ for about 15min on hi and low pumps and retest with strip, i got some movement, now its ~7/180 (by color matching)

if i am adding about 1/2fl.oz of dry per wk and only see movement in ph, does that mean i need more dry to see the movement in alk? the dose may not be the full story since % concentration of the acid plays a big role here. the dry is 93% sodium bisulfate.

so, in 1fl.oz, 93% of sodium bisulfate vs 35% ma ?? the diff in chemical reaction is ?? my chemistry is not sharp these days.....
 

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