pH continues to fall

[tscaldwell7]

FC - 4
CC - 0
pH - 7.5
TA - 110
CH - 190 *Vinyl liner
CYA - 35

My ph keeps dropping. I have added about 2.5 boxes of borax to the pool (since balancing, new pool) and my ph keeps dropping to around 7.2. I would like to keep it at a steady 7.6/7.8.... I added more borax last night and it has already dropped from 7.8 to 7.5 .. my TA/CYA has been the same since opening it in May... any thoughts? I have read through numerous forms and with my higher TA, everything suggest that the ph should be rising. I do have a solar cover that prevents aeration from rain (it is on every night, plus daytime M-F) we usually swim every evening on the weekdays when possible and splash around...

This drop may be normal, but I haven't found the forum that mentions it. Any insight is greatly appreciated, thank you!

 

[jblizzle]

How are you chlorinating?

 

[YippeeSkippy]

You're using pucks and packets of chlorine to chlorinate, right? THOSE will be the likely cause of low pH.

 

[jblizzle]

You're using pucks and packets of chlorine to chlorinate, right? THOSE will be the likely cause of low pH.

Why you gotta blow my punch line?

 

[tscaldwell7]

No I am using liquid bleach. I may use one tab in a whole month.. May put one in a floater during heavy use

would one per month cause it to drop that much?

 

[jblizzle]

No it would not.

 

[pooldv]

Adding the borax will raise your TA a bit. TA and PH should reach equilibrium at some point. Are you adding much fill water? How is the PH and TA in your fill water?

 

[tscaldwell7]

No, I have never had to add any water to our pool. However, WV had significant rainfall last week which required me to drain water twice because the skimmer was covered and overflowing. Maybe I will eventually reach that equilibrium, but it has already dropped another .2 (now 7.4) since yesterday. Oh well, Borax is on the shopping list...

 

[basod]

When you do the TA test you wipe the tip of the bottle every drop?

 

[tscaldwell7]

Not sure if I follow.. Are you asking if I wipe the bottle after each drop? If so, which of the 3 are you referring to? Sometimes I do the 25mL mark but mostly 10mL to conserve chemicals... TA always turns at 125ppm for 10mL and 110-120 for the 25mL test

 

[basod]

When you add R009 the final titration step-chemical may be different in your kit. Important to wipe tip of dropper with damp rag or it throws results off

 

[basod]

The R0007 needs to be mixed first then R-0008 before wiping between drops on the R-0009
if you are trying to half the test at 10ml probably getting an inaccurate result
unlikely you'll run out of those chemicals before they expire so use the full 25ml sample

 

[tscaldwell7]

I know it isn't as accurate but only care to know if it would jump above 125ppm and do the larger sample once a week. I follow the 1 drop mix, 5 drops mix and Multiply drops by 10 etc.. Just wiped it off and still turns at 110... Darker at 120

There is no buildup on the TA dropper.. I could understand on the corrosive R-0010 CH buffer dropper.. Why is wiping necessary?

 

[pooldv]

To eliminate static build up.

 

[JoyfulNoise]

Here's my suggestion - stop using borax to raise pH and, instead, use soda ash (washing soda or sodium carbonate....NOT baking soda). Adding borax is raising pH without much change in TA and is, in fact, making it harder to raise pH because borates tend to buffer more strongly in that direction. Use soda ash to raise both your pH and TA at the same time. Do so slowly (maybe only raising your TA by 10ppm per addition) until you find the TA level that keeps your water pH from falling.

 

[tscaldwell7]

I am already at 110 for TA so I have been avoiding washing soda.. If I were to use it today it would raise my TA to approximately 118... Isn't 120 maxing out?

 

[NeedMoreSun]

Every pool is different and finding the equalibrium is more important than a stated range. Pool School also says "sometimes higher". A higher TA will result in PH rising more easily, or in your case hopefully not drop as fast. It is also a rule of thumb and only recently did they drop the lower range due to so many of us, myself included, running with a TA as low as 60 and sometimes even lower to find our own balance.

Also, Matt is the expert but I "believe" total alkalinity includes both carbonate alkalinity and borate alkalinity, and if so your TA is partially borates which he has stated tends to resist a rise in PH.

 

[JoyfulNoise]

I am already at 110 for TA so I have been avoiding washing soda.. If I were to use it today it would raise my TA to approximately 118... Isn't 120 maxing out?

As Scott has said, the levels are suggestions, not absolutes.

Given your current water chemistry values, your CSI -0.06. If you were to raise your TA to 150ppm, your CSI would increase to +0.09. Those values are well within normal ranges. Your water is in no danger of scaling.

Use soda ash slowly and see if you can stabilize your pH.

 

[tscaldwell7]

Okay, I understand... Everything you read gives those min/max ranges and I am too OCD to let anything go outside those and mess with the pool lol... Did not realize TA could vary per user... I am out of borax and had washing soda in the garage.. Works for me. Thanks for all the help. Have a good holiday weekend everyone

 

[JoyfulNoise]

You can use Pool Math to do the calculations so do check my results - if you add 8oz of soda ash (roughly 1/2 cup) to your pool, it will raise your pH by roughly 0.2 and your TA by 7ppm. In order to avoid clouding your water, scoop up a gallon or two of pool water in a bucket and pre-dissolve the washing soda. Add it back to the pool by broadcasting it around the edges. Brush/mix your pool really well and give it 30 mins to mix in with the pump running. The test your pH and TA to see where you are at. When your pH drops below 7.2, increase it with another 8oz soda ash additions. Hopefully you will start to see the time between pH adjustments increase.

Achieving your goal of a stable pH at 7.6-7.8 may not be possible. You might want to let your pH fall and see where it naturally settles. If it falls below 7.2, then keep making the adjustments. If it stabilizes at 7.4 or 7.5, that might just be the best you can do and that pH value is fine; again, there is no "perfect pH". Any pH value form 7.2-7.8 is acceptable for pool water. When adjusting your water parameters, you do want to calculate your CSI (using pool math) and make sure you are staying under +0.3 to avoid scaling.