Stuck at high pH

[Beaker]

Greetings TFP Community.

I've been lurking a couple of years and benefited greatly from your advice. Bought a house with an older pool 4 years ago. Water is clean/clear, but gunite pool is showing its age with plaster discolorations and some surface chips. I've completely redone the equipment with a new Easytouch Load Center, the old one was a sparky rat's nest.

Fired my pool guy two years in after he let it go green while we were on vacation one summer (*twice*). TFP method has kept my water sparkly. He used tons of trichlor tabs and my CYA was through the roof (near 180). One year and a 50% drain and refill later, my CYA is now very low (around 20-30, can't quite get the dot to disappear with the Taylor kit).

On to my problem:
I feel like I use way too much chlorine/bleach compared to the stories here in the forum. My pool needs at least a gallon of 10% every other day during the summer heat to keep it between 4 and 8. Sometimes every day. I've been using a Taylor K-2006 kit to track my chemistry. My TA has always been off the charts, and correspondingly pH (pegged at max). This summer I decided to get serious and see if I could move the needle.

20 gallons of Home Depot muriatic and 10 weeks of aeration have brought by TA down from the high 300s to 130. Two gallons of muriatic at a time will lower the pH to 7.2/7.3, but it's right back to 8.0+ after a day of aeration.

I only have semi-hard water from the city's municipal supply to fill. I'm also wondering if last summers' 3-4 shock exercises with cal-hypo left too much calcium, but not sure what that does to my chemistry.

Questions:
Should I keep going lower with my TA? will it help with pH?
Is my CYA too low for my environment?
Can high calcium be caused by multiple cal-hypo shocks over time?
What chemistry symptoms can occur with high calcium (other than scaling)?
Will lower pH help use less chlorine?
Is there something in my aging pool surface causing the high pH?

I would appreciate your help/guesses to any of these.

 

[AimeeH]

Welcome to TFP

Your high TA is likely causing your PH rise. I'd continue to try to lower it.

Chlorine is consumed by organics in the pool and breakdown from sunlight--CYA acts as a sunscreen for the chlorine. You may want to raise the CYA to lower your chlorine consumption. You also "could" have algae waiting to break out. A full set of numbers from your testing would give us a better picture.

Calcium is not consumed at all like chlorine is. So if you've added it, it "could" be high (I didn't see that # posted). Maintaining good CH numbers and CSI are important in plaster pools.

 

[mdogan]

Yes, continue Acid as long as needed until get stable TA.
My pool is 12-13K Gallon CYA 30, during the summary daily average was 5/7ppm

Your pool is 22K and 7ppm is normal

By the way, you should increase CYA over 30 otherwise pool is drinking the Chlorine

 

[Beaker]

All, Thanks for the advice!
Following up on AimeeH's question, here are more of my measurements:

FC: 2-8 Maintained between 2-8 (taking about 2 gals per week now that the summer has eased off.)
pH: 8.0 Bounces back to 8.0 after muriatic (still)
TA: 120 Slowly slowly decreasing
CH: 440 (Just measured, i knew it was going to be high)
CYA: between 20-30 (can't quite erase the dot in my Taylor tube)

mdogan, agree on the CYA. I assume keeping 1 tablet in the float per week or so is slow enough that I'm not going to overshoot.

Next test: I will test the CH of my tap water!

best,
Beaker

 

[ajw22]

How much do you run your rock waterfall?

Get your TA down to 60-70 and it should slow the PH rise.

 

[Beaker]

OK two more test results:

Fill water:
CH: 80
TA: 110

So I won't be able to get my pool much lower than the 120 its at now!
But what's up with my high CH? Is that what is causing my high pH?

Is the only solution to drain and refill?

Also, what is the long term recommendation for my fill water at 110 TA? Will I need to purchase a steady supply of muriatic each season?

What are the drawbacks to 'shocking' with bleach vs Trichlor? (Trichlor is going to spike my CH, probably did last year). What will excessive bleach do? Curable with muriatic?

Thanks,
Beaker

- - - Updated - - -

- - - Updated - - -

In reply to ajw22:

I run it every day, it's a big one (1.5hp single speed Pentair pump). But with the fill at 110, probably not going to help?

Thanks,
Beaker

 

[ajw22]

CH accumulates in the pool as water evaporates and the CH stays in the pool. CH of 500 is manageable. Just keep an eye on your CSI using PoolMath When you get CH around 1000 it is time to drain to lower it.

You can still lower your TA with fill water TA of 120. Once you get it there you will need to work a bit to keep knocking it down.

There is no getting around your pool will continuously need MA.

Running your waterfall a lot each day does not help your PH problem. It aerates your water and raises your PH.

 

[mknauss]

As Allen says, you can manage them both. One, your fill water CH is quite low. My fill water CH is 250 ppm. My fill water TA is 130 ppm. I keep my pool TA at 70 ppm by adding acid twice each week during the high evaporation time of year (May-Sept).

 

[scdaren]

OK two more test results:

Fill water:
CH: 80
TA: 110

So I won't be able to get my pool much lower than the 120 its at now!
But what's up with my high CH? Is that what is causing my high pH?

Is the only solution to drain and refill?

Also, what is the long term recommendation for my fill water at 110 TA? Will I need to purchase a steady supply of muriatic each season?

What are the drawbacks to 'shocking' with bleach vs Trichlor? (Trichlor is going to spike my CH, probably did last year). What will excessive bleach do? Curable with muriatic?

Thanks,
Beaker

- - - Updated - - -

- - - Updated - - -

In reply to ajw22:

I run it every day, it's a big one (1.5hp single speed Pentair pump). But with the fill at 110, probably not going to help?

Thanks,
Beaker

Trichlor will add CYA, not CH. Cal Hypo adds CH. You could use some CYA, just careful not to overdo it. Around here, I would go at least to 40.

Fill water TA won't matter that much, you are just topping off with fill water. As you add acid, the TA will come down. Less TA will require less acid.

If you haven't already, make sure you are watching and managing your CSI level.

 

[aussieta]

and i would aim for the fc to be a bit higher