PH and TA - Chasing my Tail... I feel like it's Grounhog day :(

[First Pool Judith]

OK, I'm frustrated. I've started working on the chimicals of our pool since Dec. 2013. Here's the pattern:
Chlorine - averages around 1.5
Combined Chlorine - 0
PH - Average 7.8. It CONSTANTLY wants to rise and I find myself having to add around 60oz of muriatic acid every week to get it down to 7.4 - 7.6
TA - this averages about 60 every time I add muriatic acid.
CYA - 35-40

4/22/13 - I added 64 oz of muriatic acid and brought PH down to 7.4. TA was 60-70
4/24/14 - PH is already 8.0

Am I even doing the right thing? Does adding so much Muriatic acid have an affect on other things? Lastly - is it OK for my to be so low?

Very frustrated
Thank you for your help!
Judith, Brian's wife

 

[JasonLion]

Welcome to TFP!

Your plaster is less than a year old, so it will be raising the PH as it cures, especially since you got plaster in the fall and it has been cold most of the time since it was plastered. Also, the ozone system is providing aeration, which combined with even normal TA levels will raise PH.

Meanwhile, your FC levels are too low. You want FC at 3 or higher when CYA is around 40.

Are you using trichlor for chlorine? Using trichlor in this situation can be very problematic, not only will it raise CYA level, but it requires higher TA levels than what you mention, which increase the PH drift.

 

[pwrstrk]

Welcome to TFP !
First thing is your FC is way to low for your CYA level. You should be targeting your FC at 6-7 and never letting it get below 3. How are you chlorinating your pool ?
As for the PH increase do you have any water features ? Is this a new pool ?

 

[First Pool Judith]

Thank you for your reaponse! Yes we are using Trichlor tabs. We have the chlorine feeder set at 1.5. Should we be chlorinating with bleach right now? Also, when would it make sense to use the inline chlorinator?

- - - Updated - - -

Yes, we do have a fountain on the tanning ledge and a 12 inch sheer but have been minimally running them since we know airation impacts PH. We do have an ozonator also. Pool was built in Nov 2013

 

[pwrstrk]

No need for the ozone either. I would stop with the pucks now and switch to liquid chlorine ( bleach). The pucks will continue to add CYA , not a good thing. Your CYA is fine now.

 

[First Pool Judith]

OK, so if I'm understanding right - Free chlorines need to be a minimum of 3 with a CYA of 40.

- Will raising the Free Chlorines help stabilize the PH swing?
- If we stop using tri-chlor and use bleach to chlorinate - what TA would we want to target?
- If we maintain tri-chlor tab chloriation, what TA should we maintain?
- Is there a chemical that will help stabilize the increase of CYA with trichlor tabs?

 

[pwrstrk]

Yes FC no lower than 3.
Raising the FC will not stabilize your PH
Your TA is in a good spot when you have little to stable PH increase. Doesn't have to be in a certain range.
There is nothing to stop the addition of CYA from the pucks. Pucks are also acidic and lower PH. Still not a good reason to use them all the time.
Your best way to add chlorine with no side affects is liquid chlorine or a SWG. The pucks are bad news, plain and simple. Lots of threads on the forum about using pucks and the results you get from them.

 

[zea3]

Hi, welcome to TFP! The only practical way to lower CYA is to drain and replace water. Unfortunately there is no chemical that removes or neutralizes CYA. If someone ever invents one they could be a very rich person!

All trichlor tabs have CYA. Using trichlor tabs will add about .6ppm of CYA per tab. Since the recommended range for CYA is 30-50 you do not want to add anymore CYA to your pool. You want the TA to be between 70-120. Most pools will find a TA that keeps the pH stable within that range, but each pool is different. Since you are still in the plaster curing stage your pH will rise and it will be harder to maintain a stable pH and TA. When you lower the pH, shoot for 7.0 since you know it will rise in a short time.