What do these numbers tell you?

[bbrock]

Hi TFPerss,
I checked the water yesterday. I wanted to bounce these numbers off you all.
FC 5
CC 0
pH 7.5
TA 110
CH 300
CYA 30
water temp 87

My pool is not salt water. Resurfaced some years back to Wet Edge Satin Matrix (it's aggregate). My CSI shows things are okay. I float one puck at a time to help ease the chlorine loss, and I use a solar blanket.

I lowered my TA a couple of months ago from 100 to 80. It seems to have crept back up. If I am not crazy, I recall having read something here at TFP about the natural level that TA will find. I am beginning to wonder if in my pool, the natural baseline level for the TA is 100+.

1) Would you lower the TA in this situation? It's just that if I lower it, it may rise again.
2) Wait, and see if it continues to rise?
3) Could the surface play a part in this? Could the aggregate prefer an environment with more alkalinity?

Thanks in advance for any input.

 

[ajw22]

What is the pH and TA of your fill water?

 

[wireform]

How are you getting away with that low of a CYA this time of the year and how are you chlorinating ?

 

[bbrock]

What is the pH and TA of your fill water?

Fill water: pH 7.8, TA 170

 

[bbrock]

How are you getting away with that low of a CYA this time of the year and how are you chlorinating ?

I never thought a CYA of 30 was low. It was 20 at the beginning of summer so I raised it to 30 with CYA granules.

I chlorinate with 12.5% chlorine, or 10%.

Whether the CYA is at 30, 40, 50, or 60, I think I'll still see the same chlorine burn off. I generally see a FC drop of 0.5 - 1. When the CYA was 20, pool water temp was warm, and we were in a heat wave, I could see a chlorine drop of 1.5 ppm. Things seem to be managed just fine with a CYA of 30 and have been for many years. In the summer, I float one puck at a time to help with that chlorine drop. I use a solar blanket, so that helps with the burn off.

 

[ajw22]

Fill water: pH 7.8, TA 170

Your TA 170 fill water is causing your TA to rise. That is the only cause.

You can work on lowering TA and it will be a constant battle.

 

[bbrock]

Thx ajw22.

1) But if left untreated, then will it just keep rising? Will it naturally decrease?
2) At what level would you say it’s a must to start treating?
3) I read here that each pool has its own happy medium for alkalinity. Given this high fill water, how can I say what’s my pool’s happy medium if it could keep rising?

 

[jeffchap]

I don't see high TA on it's own being a problem. The negative aspect to it is that it causes pH to rise. If you treat the high pH with muriatic acid this will also lower TA at the same time. Hopefully you'll eventually reach an equilibrium although if your fill water is high in TA it may always remain high in your pool.

The takeaway is to deal with the pH and TA will take care of itself.

 

[mknauss]

Your use of a solar cover and floating a trichlor puck keeps your pH depressed. That is fine as long as it stays in the 7's.

TA is not a big concern as long as your CH stays low and the CSI does not creep up to scaling tendency region.

 

[ajw22]

1) But if left untreated, then will it just keep rising? Will it naturally decrease?

TA does not naturally increase or decrease. TA increases through the addition of chemicals that raise TA or higher TA water. TA is decreased by the addition of acid.

You have two opposing forces working on your TA - your high TA fill water and how often and ho9w much acid you add. Your TA will end up somewhere less then 170 depending on the two.

2) At what level would you say it’s a must to start treating?

When your CSI gets between +0.3 to +0.6 on a consistent basis.

By treating you mean aggressively lower your TA down around 60 following this procedure.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.troublefreepool.com

3) I read here that each pool has its own happy medium for alkalinity. Given this high fill water, how can I say what’s my pool’s happy medium if it could keep rising?

Your pool will also have a medium for your TA between your fill water and your acid additions.

What you need to watch is what your CSI is at that TA.

 

[bbrock]

Thank you for the replies this morning. I think I got it in that you’re saying that normal acid addition would help to keep the TA in check.

However, that made me realize that with floating the one puck, even though that it is acidic, that has been keeping me from needing to add MA weekly (approximately) to lower my normal pH rise. So perhaps TA has had an opportunity to rise easier because it’s not being controlled with the acid. Could that be the case?

Yes the one puck does help to keep the pH steady. But I think I’m going to remove the floater, and watch the pH rise and handle it accordingly.

Yes, when I talked about treating the TA, I meant doing it the involved way with the acid additions and the aeration. That’s what I have done before.

 

[ajw22]

So perhaps TA has had an opportunity to rise easier because it’s not being controlled with the acid. Could that be the case?

Large doses of muriatic acid lowering the pH from 7.8 to 7.2 will lower the TA more then the slow acid addition of trichlor tablets.

 

[mknauss]

You need to leave the pool uncovered to get pH rise.

 

[bbrock]

Mknauss, you’re right my friend. Thank you for that. Yeah areation.

All right, got the floater out, cover off, let’s see how quick the pH rises.

 

[mknauss]

Throw five or six kids in the pool and the pH will rise -----

 

[bbrock]

Good one. Yeah that will surely do it!

Previously when I had lowered my TA from 100 to 80, I was aerating with our sump pump. I had it on one of my steps and it was breaking the surfacace enough to help cause aeration (probably could’ve put it on the top step and tilted it back in the pool to throw a lot more aeration).