Low PH

  • Last Post 03 July 2021
  • Topic Is Solved
KGolden posted this 14 June 2021

Just opening my pool in Northern New York. Green water of course. Have vacuumed all debris and checked my ph and chlorine levels. Ph is below 6.8. No chlorine reading at all. I’ve added 3 lbs of sodium bicarbonate and have been running pump and backwashing 24/7. How do I get the ph up to where I can actually put my chlorine in?

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JCMC70 posted this 14 June 2021


Can you give me some additional information please?

What kind of pool do you have, above ground or in ground?

If in ground, what type (vinyl, concrete, plaster, fiberglass)?

How many gallons of water does it hold?

What kind of test kit do you have?

The latest readings for the following:

  • PH
  • Total Alkalinity 
  • Calcium Hardness 
  • Stabilizer (CYA) level


KGolden posted this 15 June 2021

My pool is above ground 15x30 with about 12,000 gals. The test kit I’m using is TF-100. 

My PH is below 6.8. Shows yellow in the block. 

My TA stay pink when T0007 & T0008 is mixed. Does not turn green. 

My CYA is 100. 

KGolden posted this 15 June 2021

Not solved hit wrong button 

KGolden posted this 15 June 2021

I’m new to this forum and I hit the solved button by mistake. Needless to say my problem is not solved. 

JCMC70 posted this 15 June 2021

"The test kit I’m using is TF-100."

  • The TF-100 FAS/DPD test kit is one of the most recommended. I use the Taylor K-2006 kit.

If the TA test color isn't changing no matter how many T0008 drops you use, obviously there isn't any TA in the water. Most places/articles tell you that the range for TA is 80-120 ppm. 80 ppm is all you need. We can adjust that with a common household product, baking soda. 
In a 12000 gal pool, 2lbs of baking soda will raise the TA by 12 ppm. So you're gonna need about 13 lbs. So go get 7- 2 lb boxes of baking soda.

But don't put it all in at once. With the pump running, sprinkle 3- 2 lb boxes into the pool. If clumps come out and settle on the bottom, take the pool brush and break them up so they will dissolve. After 1 hour take a fresh TA reading and adjust from there. Or come back here and let me know what the new reading is and I will adjust for you.

An added benefit to adjusting the TA first is the baking soda will also raise the PH. So take a fresh PH reading also. It probably won't raise it as much as we need, but if the PH still needs to be raised after the TA is correct we will handle that with another household product.

However, there is another issue that you might want to address before any adjustments to TA or PH.

The CYA level is about 2.5 times higher than the ideal range of 40 ppm.The ideal CYA level should be about 40 ppm. At higher CYA levels you have to have a higher ppm of chlorine to do the same sanitizing that a lower concentration chlorine needed at the lower CYA level.

The amount of chlorine in a pool with 40 ppm of CYA  should be kept at 3 to 5 ppm.

The amount of chlorine in a pool with 100 ppm of CYA should be kept at 11 ppm. You can see that it takes 2 to 3 times as much chlorine to sanitize a pool with 100 ppm CYA.

If you decide to lower the CYA level in your pool there are only 2 ways that I know of to do it. Draining some of the water out of the pool and replacing it or an expensive reverse osmosis process.

If you decide to lower the CYA in the pool, I would start with about a third of the water.

If you decide not to lower the CYA level just be aware that you are gonna need higher levels of FC to properly sanitize the water.


KGolden posted this 16 June 2021

Thanks J I will try and let you know how I make out. 


KGolden posted this 21 June 2021

I’m ready to give up 😏. I’m draining about a third of my pool water. Can I do this on backwash?

JCMC70 posted this 21 June 2021

Does the multi-port valve on top of the filter have a drain or waste setting? If it does it would be better to use that.

Also, will that drain enough water? The drain, waste or backwash settings will only drain water down to the skimmer.

KGolden posted this 28 June 2021

Ok so replaced 1/3 of water to pool. My readings are much better but now it’s cloudy. I did add chemicals to reach my readings. 

Chlorine is at 5

ph is at 7.5

calcium hardness is at 50

alkalinity is at 70

and cya is at 40. 

Now how do I clear the cloudyness?

JCMC70 posted this 28 June 2021


Shock the pool and maintain the shock level until the water clears. This procedure is known as SLAMming.

The SLAM level of chlorine for water with 40 ppm of stabilizer is 16 ppm.  The recommended chlorine to use for slamming (and for an every day sanitizer) is liquid chlorine.  Liquid chlorine doesn't add anything to the water but chlorine and a little salt.

Dedicated "Pool Chlorine " can be found in 2 strengths, 10% and 8%. Your can even use household bleach but most bleach concentrations are 4 to 6%. And they shouldn't have any additives like scents or conditioners or softeners. All Clorox bleaches except Clorox Sanitizing Bleach use the ColorMax technology, so you can't use any of them except the Sanitizing Bleach.

If you can't find liquid bleach we can do this with dry granules. I would recommended 65% Cal-Hypo. This will add calcium to the water, along with chlorine, but you aren't in any danger of exceeding calcium levels.

Here's the process:

Turn the pump on, backwash the filter then let the pum run throughout the process.

Bring the chlorine level to 16 ppm. If you initially have 5 ppm, you will need to add 11 ppm.

For 10% Liquid Chlorine:

13 ounces of 10% chlorine will add 1 ppm to the water, so you will need to add 142 ounces (or 1 gallon, 1 cup and 6 ounces)

For 8% strength:

15 ounces will add 1 ppm to the water. So 165 ounces would be needed.

Measure out the amount needed and slowly pour it in front of the return jet.

For 65% Calcium Hypochlorite:

2 ounces will add 1 ppm to the water. So 22 ounces total.

Add the Cal-Hypo to a 5 gallon bucket of water, about 3 ounces at a time and thoroughly dissolve the cal-hypo before slowly pouring it in the water in front of the return jet.


With the filter running continuously, wait about 3 hours and take a new chlorine reading. If the reading shows less than 16 ppm, backwash the filter if the pressure level says you should add enough chlorine/cal-hypo to bring the level back to 16 ppm. Repeat this cycle every 3 hours or so.

Take your final chlorine reading for the day just before sunset, bring the level back to 16 ppm and let the pump run all night 

Get up the next morning and repeat the process.

You should have to add less and less chlorine to keep the level at 16 ppm.

Once you get to the point where you are only adding 1ppm or less of chlorine at each reading, you are ready for the overnight chlorine loss test. To do this, take the final daily reading just before sundown. If the chlorine loss is 1 ppm or less from the reading you took before that, don't add anything, just note the chlorine level. Then the next morning after sunrise take another chlorine reading. If the chlorine loss is 1 ppm or less, all of the organics should be dead.

At this point test for combined chlorine. If that level is 1 ppm or less and the water is clear, you are finished with the SLAM.

Let the chlorine level drift back to the normal 4-5 ppm and resume your normal chlorination method.

You should vacuum and brush the pool daily during this process. And backwash the filter when the pressure says you should.

If you have any questions, let me know.


KGolden posted this 28 June 2021

Thanks J will try it. Hopefully I’ll get it right. Thanks for the help. 


KGolden posted this 28 June 2021

Sorry J one more question. I’m using a liquid chlorine that has 12.5 % sodium hypochlorite, how much should I use?



JCMC70 posted this 03 July 2021

Sorry, I just saw your last post.

With a CYA level of 40 ppm, the SLAM level is 16 ppm.

With 12.5% chlorine, 12 ounces will raise the chlorine level 1 ppm in 12000 gallons of water. So take a chlorine reading, subtract it from 16 and multiply that number by 12.

Once the pool is back to normal you should keep the chlorine level between 3 and 7 ppm with 3 being the absolute minimum.

Again I'm sorry I missed your last post.