How Much Baking Soda To Raise pH Level

by Kar
(South East Arkansas)

We just opened our 22,000 gallon above ground pool. We also just purchased a new DE filter and pump.

My husband used 5 bags of shock, we put algeacide in it yesterday, and I put chlorine tablets in a floater today. I tested it and the chlorine is high and the pH is reading 6.8.

How much baking soda do I put in to raise it?

Also the pump is reading this ok, or do I keep bumping it? Any feed back would be appreciated.

Thanks for the question Kar

I'd like to have the rest of your complete chemical readings:

Chlorine, CYA (cyanuric acid/stabilizer), Alkalinity, Calcium Hardness, and Metals (iron and copper) and names of any algaecides you may have used along with clarifiers, phosphate removers, and/or flocs.

It's 1 lb. of bicarb to raise your pH 0.2 per 10,000 gallons. You'd use 2 lbs. per 20,000 gallons. You want to raise it to at least 7.2 - 7.4 so I'd start with 3.5 - 4 lbs.

Adjust Swimming Pool pH Levels

Get a 5 gallon bucket and fill it with pool water, add the bicarb, stir with a stick, then broadcast it around the perimeter of the pool with the pump on FILTER. Do this at night and allow it to run for 8 - 10 hours, retest, and make another adjustment if needed.

Before you do this it's important to know the CYA/stabilizer level. If it's high, above 80ppm, you need to do a partial drain and refill to get it to the proper level of 30 - 50ppm. There's no chemical to reduce the CYA.

What is the "just back-washed" reading on your filter? Normally they run between 8 - 12psi. Are you using a real DE scoop? You shouldn't be using anything else like a coffee can. You won't get the proper coating and might be adding too much DE.

It's 1 pound of DE for every 10-12 square feet of filter space. Basically it's this: 48sf. DE filter = about 4 pounds of DE. This is a general rule so you need to check your owner's manual for details and exact specifications.


Click here to post comments

Return to Pool pH.

pH Too High In New Diamondbrite Plaster Pool

Newly Diamondbrite plastered pool 30,000 is gallons. The pH is 8+ with no free chlorine all. Other numbers are in check.

How do I lower pH? Dry acid has not worked to lower levels yet. Have used 10 pounds in the past three days.

Thanks for the question

This is an area of concern for many pool owners that have their pools replastered. Here's my take on it.

What's happening is the curing of the plaster. This is when water is added to the uncured pool plaster. The plaster starts to cure and then turns to calcium hydroxide. Normal pool plaster that is already cured is calcium carbonate.

This means the uncured plaster is absorbed in the water. It then crystalizes and releases the calcium. This raises the calcium hardness (CH) as well as the pH.

For every 10 ppm rise in CH, it takes 25.5 fluid ounces of Muriatic Acid per 10,000 gallons to lower the pH and compensate for the rise.

When the plaster is in the process of curing, the requirement is to add 1 gallon of acid per 10,000 gallons of water which roughly corresponds to an increase of 50 ppm for the calcium hardness. It needs to be noted that the rise in CH is not always the case. For fill water with low CH (below 50ppm) the water will leach calcium from the new plaster at a higher rate. But, if you have high CH (say above 100 - 150ppm) in the fill water, this won't happen as fast. You can expect only a 10ppm or so increase in CH.

This is depended on the plastering workmanship was good, the plaster was high quality, and the water balance is maintained.

Your pool is producing calcium hydroxide. The question is how to deal with it. There are normally 4 kinds of start ups for newly plastered pools. They are:

  • Acid startup - This is where enough acid is added to lower the pH to 4.5 and alkalinity to zero for three days
  • Bicarb startup - This is a water treatment with sodium bicarbonate
  • Traditional startup - The water is slightly alkaline but increases as pH rises
  • pH-neutral - The pH is brought to 7.0 then balanced after 3 days

    It sounds to me like your pool plaster company opted for the bicarb set up but you may want to confirm with them.

    A pool that uses the bicarb startup will usually have a pH of 8.3 because the pH will rise from the curing of the plaster. It can be lowered with acid to the 7.8 range.

    The total alkalinity (TA) will probably increase for the first month or so. You can add acid to lower the TA and get the pH to the desired range of 7.4 - 7.8.

    The question really is, "How do I get the plaster to cure and go from calcium hydroxide into calcium carbonate without driving me insane?"

    It normally takes about one month for the new pool surface to be converted from calcium hydroxide into calcium carbonate.

    You're also dealing with the CSI - Calcite Saturation Index. Some may call it the Calcium Saturation Index. That is way too long to go into detail but here are some good links for further study:

    There's a guy named Kim Skinner that has done wonders for the pool industry, especially for new pool plaster start-ups. You can information here:

    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.

    If you need immediate assistance (within 24 hrs) or for emergency personal assistance, you can make a donation of $35 per hour and I'll answer your questions by phone.

    If you've found this site helpful please consider making a donation. Thank you.

    Hope this helps and have a great Summer.


  • Click here to post comments

    Return to Pool pH.

    pH Is A Little High In Our Above Ground Pool W/ Salt Generator System

    by Anthony
    (Airway Heights, WA)

    My PH is aboove 8.5 and Muriatic Acid seems scary to use being its a pvc type above ground pool, we recently dumped the pool and refilled it due to major cloudy water.

    We added the two 40 lb bags of salt that we used last time to get the right ammount in the pool, even though the bag suggests that one 40 lb bag does 10,000 gallons of water which is not even a close estimate to what the our 5000 gallon pool required.

    My PH is high and I do not want to have to go through a lot of trouble in refilling the pool again, any suggestions. on how to lower the PH to get it down to reasonable specifications. I am willing to use Muriatic Acid if need be, but only if its absolutely necessary to acheive the proper PH.

    Thanks for the question Anthony

    You have your choice of 2 kinds of products to lower the pH; muriatic acid and sodium bisfulate. Most of the time the acid is a little less expensive than the sodium bisfulate. To get something from a high pH alkaline state to a more acidic state you need to add acid. Yes, your pH is high at 8.5 and optimal range is between 7.6 - 7.8.

    You don't need to refill your pool. It's a shame that you had to in the first place, but this needs to be understood. Chlorine reacts better at a slightly lower pH. At 7.2 - 7.4 you still have 50% of the chlorination properties. 7.6 - 7.8 it's 45%. Not until you reach 8.0 - 8.2 does it take a fast nose-dive and goes to 25%. If you're running the pH as 8.2 or higher you're using a very small amount of the active chlorine. And cloudy pool water is one of the first signs of an early algae bloom.

    Lowering the pH is very simple and can be done in a couple of stages. Get a bucket filled 1/2 with pool water, add the acid, and stir with a stick. Broadcast it around the perimeter of the pool on FILTER, sweep very well, FILTER for for 8 - 10 hours then retest and make another adjustment if needed. It's 6oz. of acid to lower the pH 0.2 per 5,000 gallons.

    Swimming Pool pH Levels

    Pool pH

    If you need immediate assistance (within 24 hrs) or for emergency personal assistance, you can make a donation of your choice and I'll answer your questions by phone.

    Contact Me


    Hope this helps and have a great Summer.


    Click here to post comments

    Return to Pool pH.

    pH Related From Spain

    by Fiona

    GREAT site. We have been successfully maintaining our chlorine pool ourselves for years. Pool had turned green after heavy rains. I had to add pH+ a week ago. Diluted it and did all the usual right things . Yesterday I cheched ph using the ususl standard phenol drops. pH was ok. I had left the pool water/ phenol solution in the tester tube. When I came back half an hour later the Liquid in the tube was dark pink ( ie VERY hi pH reading.) I re-did the test today, same results . pH reading a minute after taking the test was fine, left the tube, came back, later and it had changed to very dark pink over half an hour.

    Is this the true indicator of the pH in the pool !? Does the colour of the water with the phenol on it. change when left in the tube over time.? I am now thoroughly confused? Readings TC 10 FC 20 TA 80 CYA around 70-90 (on the strips) pH 7.4. Upon putting in the drops, and then 8.0 when left. For about 20 mins. Many many thanks in advance.

    Hi Fiona. Your best reading is when you immediately look at the color. Using fresh drops will give you the correct pH level. 7.4 pH is right in line. My concern would be your higher CYA level. Once it gets that high you might consider doing a 2/3 drain and refill. The 2 - 4ppm FC is dependent upon the CYA being in the range of 30 - 50ppm. Once the CYA starts to get into the range of 80 - 100ppm you'll need to run the FC at 7 - 8ppm for it to be effective. Your other readings are fine. The FC is a bit high but nothing to worry about. It'll naturally decrease.


    Click here to post comments

    Return to Pool pH.