How pink is pink for FCl?

[vaubach]

So I'm trying to use my Taylor FAS DPD test, and it's just the slightest hint of pink after I put the two scoops of powder in, and then turns clear right away with the first drop of the reagent. I feel like I have put a lot of chlorine in the water the past few nights, surely it can't really be that close to zero? Water is clear and has been since opening 6 days ago. A few leaves in the bottom and pollen on top, but nothing major.

Other numbers: pH 7.4, alkalinity 184, CYA 26. Weather has been cloudy for several days, so water is cool.
I have used 2 gals 8.25% bleach, as well has 4 lbs of Sodium Dichlor granules (still building up CYA a bit since pool was on Pristine Blue last year). I had also added muriatic acid initially to bring the pH down from the starting point of 8.2, and alk started at 258, so I guess at least that is making progress.

Am I doing something wrong with this test? I even tried faking a sample with a drop of bleach in a bottle of water and it was pink but only for about 2 swirls of the powder, never mind adding the next step.

 

[mrcarcrazy]

It should only require one scoop of powder. 10ml sample size?

Have you tried the regular Chlorine test that's the other 1/2 of the pH test?

Basic how to video:
https://www.youtube.com/watch?v=PHQG4tgQsFE&ab_channel=TF100TestKit

your TA sounds way high...I guess you know that...but I had to point it out.

 

[Patrick_B]

That means very little FC. ONE scoop is enough. If there is ample FC it is vivid pink.

When you did the bleach in the bottle, it was high, and it bleached out the color.

Sounds like you need to SLAM this pool. Read the link in My sig line, and ask questions before you start.

 

[vaubach]

Yes, 10mL sample. Maybe I was using too much powder then? The instructions say if pink color disappears, add powder until it turns pink.

 

[mrcarcrazy]

follow the video and get back to us on how it worked for you.

 

[vaubach]

I watched the video and, yeah, my test definitely wasn't pink like that. Ok, so according to the poolmath calculator, if I add two lbs of Dichlor it should raise my FCl by 11. So I will try that, since my CYA could go a little higher anyways. I'll also add some more muriatic acid to keep trying to get the alk down. We are on a well here, very "soft" water, and the water starts pretty basic with high alk and next to no calcium. I read that CH isn't so important for vinyl pools, so I haven't bothered trying to adjust that.

 

[mrcarcrazy]

I watched the video and, yeah, my test definitely wasn't pink like that. Ok, so according to the poolmath calculator, if I add two lbs of Dichlor it should raise my FCl by 11. So I will try that, since my CYA could go a little higher anyways. I'll also add some more muriatic acid to keep trying to get the alk down. We are on a well here, very "soft" water, and the water starts pretty basic with high alk and next to no calcium. I read that CH isn't so important for vinyl pools, so I haven't bothered trying to adjust that.

Sounds like you've been doing your homework. Seriously, thank you for that!!

Just don't get too carried away with the DiChlor.

 

[vaubach]

Added 1 gal of bleach, 1 lb of Dichlor, scrubbed pool, scooped leaves, added acid. Fingers crossed I will see some increase.

 

[vaubach]

So that's what pink looks like. I got a FCl reading of 7 yesterday afternoon, and again this morning, with a CC of 0. That's good right? Other numbers: pH 7.3, Alk 162 (still high), CH 68, CYA 28. Do I still need to work on that alkalinity some more with more acid? I have some "pH minus", but I'm not sure if that will drive alk down or not.

 

[JasonLion]

Yes, that is good

You will want to work on lowering TA over time, but there is no rush on that. Any acid, including PH Minus, which we call dry acid, will lower TA. But you can't lower it too much at one time, because then the PH gets too low. You need to lower PH until it gets to around 7.2, and then wait for the PH to come back up before adding more acid.

 

[vaubach]

Super. It's still way too cold to swim in, but hopefully sunny days are on the way to warm it up a bit and maybe that solar coil heater will help.

 

[Richard320]

Vicki, how are you getting those readings other than FC? I can see guesstimating CYA on the view tube scale, but where did the 162 TA and CH 68 come from? Are you using a digital tester of some type?

 

[vaubach]

Yes, a Lamotte ColorQ 7. My initial tests were run at my local pool store however.

 

[duraleigh]

Do I still need to work on that alkalinity some more with more acid?

Not really, you can let it come down slowly on it's own (weeks) or you can bring it down quickly but not with acid. The correct way to reduce TA is to follow the procedure found in Pool School. It will ultimately reduce your TA and leave your pH alone.

 

[Richard320]

Yes, a Lamotte ColorQ 7. My initial tests were run at my local pool store however.

You might want to use the search function with terms like "colorq accuracy"