First Water Test Results + Questions

NorthernHAM

Active member
Apr 3, 2021
44
Northern Ontario, Canada
Pool Size
8000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hi!

I did my first tests with the K-2006C kit after the water circulated for 4 hours. I am planning to do another test tomorrow after it's been running for 24, but these are the prelims

FC- 1 ppm (see question and pic)
CC- 0
pH 6.5 (pH probe); with test kit it took 13 drops base demand reagent to reach 7.0
TA- 30
CH- 500
CYA- 120 (cut with DI water)

Plan of attack (pending the results after the 24 hr circulation) begins with the draining of 2/3 of the water and refilling it I suppose (n) As I can't test for the TDS in my pool or fill water, and the temperature is the same, it doesn't seem realistic to do the drain/fill process? From what I understand, as I have an above ground pool, while it's not great for the pool walls/liner dependent on weather, it's not as damaging as if I had an in ground to drain and then fill up after. Or is there a way to determine the TDS easily?

Question regarding the FAS-DPD: I added 4 scoops of the DPD powder and this is the furthest colour change I could achieve. The powder was also clumping up after the second scoop and did not dissolve even after aggressive shaking. I tried the test with both a 10 and 25 mL cut and the same thing happened. The 1 ppm FC is based on 5 drops of R0871 reverting the colour in the picture to clear. Is there something I am doing wrong? I was expecting a bright pink similar to phenolphthalein titrations.

Thank you!
 

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needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
4,955
Sydney, NSW, Australia
Pool Size
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Surface
Plaster
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Salt Water Generator
Welcome to TFP! Good to have you here :)

Yes, you'll need to drain about half the water and replace it. You could probably manage by just draining off 1/3 and refilling if need be.

With CYA diluted by half, raise your FC to 6 ppm FC with chlorinating liquid. Keep it above 4 ppm FC. Don't use any solid forms of chlorine such as the white pucks of trichlor or the white powder that is dichlor.

Use the 10 ml sample size for FC, and one scoop of powder. Each drop will be 0.5 ppm FC. Once you have the FC up to normal, the water will be more pink after adding powder.

I suspect the fresh water will bring your pH up. It's probably down low from powdered of solid chlorine.
 

NorthernHAM

Active member
Apr 3, 2021
44
Northern Ontario, Canada
Pool Size
8000
Surface
Vinyl
Chlorine
Liquid Chlorine
Welcome to TFP! Good to have you here :)

Yes, you'll need to drain about half the water and replace it. You could probably manage by just draining off 1/3 and refilling if need be.

With CYA diluted by half, raise your FC to 6 ppm FC with chlorinating liquid. Keep it above 4 ppm FC. Don't use any solid forms of chlorine such as the white pucks of trichlor or the white powder that is dichlor.

Use the 10 ml sample size for FC, and one scoop of powder. Each drop will be 0.5 ppm FC. Once you have the FC up to normal, the water will be more pink after adding powder.

I suspect the fresh water will bring your pH up. It's probably down low from powdered of solid chlorine.
Thanks for the reply!

By draining only 1/3, that would only bring my cya to 90, seems high still!! Half would bring it to 60, but pool math says to drain 5-10% extra to account for error.

As for the DPD test, I did have a feeling it should be more pink. I guess it's just because I have almost 0 chlorine in it at all.

And unfortunately I measured the pH of my fill water and it's 6.8 so it won't be raised by much! The plan was definitely to use liquid chlorine, I've learnt so much from this site! :)
 

needsajet

TFP Expert
LifeTime Supporter
Jan 4, 2016
4,955
Sydney, NSW, Australia
Pool Size
44000
Surface
Plaster
Chlorine
Salt Water Generator
Unless noise is an issue, fill the pool with an arc of water, so the water slashes when it hits. That will help the pH start to go up (aeration).

But yes, sounds like you can add some bicarb (sodium bicarbonate, baking soda). Use pool math, but I believe around 1 kilo will set you up closer to correct. Double check your fill water for TA first though. If it's 50 or 60 ppm TA, the pH will come up on it's own in a few days, and there's no need to add chems to raise alkalinity.
 

NorthernHAM

Active member
Apr 3, 2021
44
Northern Ontario, Canada
Pool Size
8000
Surface
Vinyl
Chlorine
Liquid Chlorine
Unless noise is an issue, fill the pool with an arc of water, so the water slashes when it hits. That will help the pH start to go up (aeration).

But yes, sounds like you can add some bicarb (sodium bicarbonate, baking soda). Use pool math, but I believe around 1 kilo will set you up closer to correct. Double check your fill water for TA first though. If it's 50 or 60 ppm TA, the pH will come up on it's own in a few days, and there's no need to add chems to raise alkalinity.
That's a good tip on the filling, I can't believe I didn't think of that. I will do that when I'm on the filling stage.

I will check the fill water for TA, but I am concerned about the pH staying low for too long because of my heater. Hopefully refilling it will adjust the TA to a more reasonable number! I think I'm only going to add chemicals once it's refilled and circulating again, just to be safe!
 
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