Can't Get pH To Go Down

by Jennifer G.

I have a 3,700 gal easy set pool...set it up and shocked water turned yellow green instantly - was told I had excessive amounts of iron in water.

Added chelating agent (not sure on spelling) to get metal out and vaccumed out settled minerals about 5 times a day for the last 4 days.

I have added 1 cup of pH minus each day for 4 days and the pH and total alkalinity are still at the highest colors on my test strips. They don't seem to be coming down at all.

The water has now cleared and has just an extremely light yellow tint but why can I get that dang pH and alkalinity down.

Any advice would be much appreciated.

Thanks for the question Jennifer and I hope you get this answer. Next time you need to fill out the question form completely. If you don't add your email address, (nobody else sees it. It's only to let you know when your question is answered by me) you may not know when the question is answered.

Yellow or discolored water can be one of two reasons, or both. The first is metal in the water, and the 2nd is organics. This is mainly leaves. The part of the leaf that makes water a brown/yellow color is Tannins. Tannins are what gives tea its brown color.

If it's metal, you'll need a good metal sequestrant. You used a chelating property, which is good. The only chelating agent that is commonly used in pools is EDTA (amino polycarboxylic acid derivative).

The majority of chelating products for pools and metal are sequesterants based on HEDP or other phosphonic acid derivatives are not amino polycarboxylic acid derivatives.

All chelating agents are sequesterant but not all sequesterants are chlelating agents.

Some popular brands are Jack's Magic Blue, Purple, and Pink Stuff, Metal Magic, Metal Free, and Metal Klear.

If you have high metal in your fill water, then you're going to need to manually dose your pool each week with a metal sequesterant. A
metal sequestrant does not remove metal from pool water. It holds it in solution until it can get filtered. Then you backwash the metal out.

Now your pH and alkalinity. First thing to know is what is the pH and alkalinity of the fill water. If they're both high you might have an uphill battle, but it can be won with persistence.

Be sure you're using enough acid and broadcasting it around the perimeter of the pool with the pump on. Allow for 1 full turnover of the water before testing and making another adjustment. This is normally 8 - 10 hours. Make the adjustment in the evening then retest in the morning.

Swimming Pool pH Levels

Pool pH

To reduce the alkalinity you'll use muriatic acid, but with the pump off and application in one spot. Allow to sit for 3 - 4 hours, then turn the pump back on and allow for 1 turnover of the water. Very gently sweep the bottom of the pool to break up any hot spots.

Have you taken a water sample to your local pool store? You might be getting a different reading on your strips.

To reduce the pH 0.2 you'll use 6oz. of acid per 5,000 gallons.

To reduce the alkalinity 10ppm, you'll use 0.8 qrts. of acid per 5,00 gallons.

Pool Alkalinity

Total Alkalinity

You may need to do this in the morning and evening until you reach the target pH range of 7.6 - 7.8 and alkalinity of 80 - 100ppm, 120ppm being the top. Have patience and persistence and they both will come down.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Swimming Pool pH" category.

Check back to this post for updates or answers.

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Hope this helps and have a great Summer.


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Keeping PH below 8 when the fill water is above 8.

by Phil Surles
(Malakoff, Texas)

I have an approximately 24k gal in ground pool that I just had re plastered with diamond brite plaster. The PH of our tap water is about 8.2 and I have to add about a gallon of acid per week to keep my pool ph in the 7.6 range. Is this normal or is evaporation etc causing my auto fill to keep adding water. My pool has both a water fall and is negative edge. I keep my ta in the 80-100 range. My pool is a salt water pool about 12 years old. I had the problem before i re plastered but not as bad. I just do not want to have scale build up on the new job as I had before. I had the pool acid washed twice before I re plastered.

Thanks for the question Phil. My first question would be was the start-up procedure correctly finished? Each company has their own procedure for start-ups and I'll assume yours was no exception. I believe Diamond Brite requires an acid start. If it's not done correctly you can have a residual pH issue. Then there's the high fill water pH. Nothing can be done about that other than adding acid to lower and maintain the pH. Then there's the issue of a chlorine generator. Many salt pools will have an increase in the pH due to the chlorine cell's production of hypochlorous acid. Next would be the waterfall. Movement in the water including water falls will produce bubbles. These bubbles burst and release carbon dioxide (CO2) which will cause the pH to rise. And last would be the use of granular chlorine, specifically calcium hypochlorite. This has a pH of 12 and should rarely be used.

Everything here would contribute to a high pH issue. Let's say the start-up was done correctly and the TA is in line. You're left with the high pH fill water, chlorine cell, waterfall, and possible calcium hypochlorite use, which you can avoid.

Be sure your using a good test kit to test the pH. I recommend and use the Taylor K-2006 kit.

If you feel your situation is more complex than this, I do phone and/or SKYPE consultations. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias. If you purchase a personal phone consult you'll get all 3 eBooks for free.

Pool Consultation

Clear Blue Pool eBook

How To Clear Up A Green Pool eBook

Swimming Pool Resources


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