pH low, TA low -- which first?

[Wobblerlorri]

Now that we have the plumbing done, it's time to open. I ran the tests today, and got this:
FC 20 (hubby added a big wallop of chlorine yesterday)
CC 0
pH 6.3 (color block test)
TA 40
CYA 0

I know TA and pH are connected, and that pH at high Cl2 levels is not reliable. I'm pretty sure I know the answer, but wanted to check -- should I adjust pH or TA first? I have baking soda on hand but will have to get some borax tomorrow.

I'm leaning toward adjusting TA first.

 

[Texas Splash]

That's a very odd/low pH. No chance there was a testing error? 5 drops of R-0014?

 

[Jimrahbe]

I thought that our pH test was invalid if the FC was over 10 ppm??

Jim R.

 

[Wobblerlorri]

Yep, brand new reagent, clean and rinsed color block. I'm thinking I'll test it again with the pH meter. It is very low, isn't it...

 

[Texas Splash]

It is very low, isn't it...

It is. I know an elevated FC level will cause the pH to give a false (temporary) high reading, but I didn't think low. Curious to see what you get with the meter.

 

[Jimrahbe]

I have no clue, it just seems that 6.3 is awful low and suggests some kind of testing error.

Thanks,

Jim R.

 

[Wobblerlorri]

It's raining now, or I'd go test it again. I'll get the meter after it tomorrow.

 

[Saturn94]

It is. I know an elevated FC level will cause the pH to give a false (temporary) high reading, but I didn't think low. Curious to see what you get with the meter.

That’s what I thought as well. With CYA at 0 and FC at 20, is it possible the pH reagent is being bleached out? That’s a lot of FC with CYA at 0.

 

[Texas Splash]

Let's see if we can get a new of eyes on this scenario with @JoyfulNoise. See if we're dealing with reagent bleaching out, false readings, or something else.

 

[JoyfulNoise]

You can add 10-20ppm worth of Alkalinity Up (I sell a special “Joyful Blend” for $8.99/lb … it’s even compatible with salt water pools…) as it will raise TA and help correct the pH if it is truly that low.

Next time tell hubby to chill out with the chlorine bomb . Geez. Get your CYA up to 30ppm.

The pH reagents aren’t going to be good with an FC that high. And yes, chlorine causes a false high pH so if that pH reading is that yellow, your pool water pH is very low.

More data please.

FYI - you can still test when it rains. Just use a sample stick to draw water from a few feet below the surface.

 

[Texas Splash]

I sell a special “Joyful Blend” for $8.99/lb … it’s even compatible with salt water pools…

Did you ever work at a pool store? Ha ha

 

[Wobblerlorri]

Trouble with testing in the rain is I'd get wet! No thanks.

 

[Wobblerlorri]

Ran another full complement of tests this morning, here's what I got
FC 6.5
CC 0
pH 6.8 color block
TA 40
CYA 0

Have to wait for hubby to go to the store before I can adjust pH. Need borax, doncha know. I had to use the color block because my meter went cuckoo for coco puffs -- kept cycling through numbers and always decided the pH of everything was 0.81. Even the air.

PoolMath said to add 1 lb 6 oz borax for the pH, 2 lb 6 oz bicarb for TA, and 2 lb CYA. I just now added 2 lb bicarb and have 1.5 lb CYA hanging in front of the outlet. Sneakin up on the correct values, you know. Borax will be added this afternoon, after testing the water again to see what the TA is. And the pH.

I'm wondering now if I misread the color block. After adding the phenol red, the water in the block went bright red, not yellow. That would stand to reason if the high chlorine drove the pH up. So just goes to show that even experienced pool owners can make a mistake.

Don't test when you're bone tired!

 

[mknauss]

Just use baking soda to raise the TA 20-30 ppm. pH will resolve itself.

 

[Wobblerlorri]

Did a pm check, here are the results

FC 4.0
CC 0
pH 6.8
TA 90

Didn't test CYA yet. 24 HR wait, you know. The TA looks good now, so I added 2 lbs 11 oz borax to correct the pH, as well as 2 ppm Cl2 to bring it up to 6. Once my CYA is in line, I'll do a SLAM because the water, though crystal clear, has a slight green tinge to it.

 

[mknauss]

You will likely have to add acid to lower the pH for SLAM. The TA was high enough that the pH would rise on its own.

 

[Texas Splash]

Are you on a well? The chlorine you are adding with no stabilizer could be a reaction to metals. Algae? ... maybe, but if you are on a well let us know. Definitely get that CYA to at least 30. Maybe let us know before dark if you see any changes in that pH. It really should be moving up by now.

 

[Wobblerlorri]

I'm on city water. Haven't had a problem with it for 3 years, and our house plumbing is all pvc. I'll test the tap water and run another set of numbers.

 

[Texas Splash]

Okay. Personally I'd rather it be green tint from algae as opposed to iron or copper. But we'll watch for a follow-up on testing a little later.

 

[Wobblerlorri]

Tap water results

FC 0.5
CC 0
pH 7.4
TA 40

Pool test 630 pm

FC 3.5
CC 0.5
pH 7.3
TA 80
CYA 20

As soon as I have CYA up to 30 to 40 I'll start the SLAM. Of course after lowering pH to 7.2.