Hot tub with BBB & Borax

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Richard, I'm having to double-check your numbers again... if it's
5 fluid ounces of 6% bleach per person-hour, and
1-2/3 teaspoons of bleach per person-20-minutes,
that means 5/3 ounces = 1-2/3 teaspoons which is 5/3 teaspoons.

I can never remember the spoon-to-ounce ratio but I know it's not 1-1!
--paulr
 
Thanks...we are watching "everything" closely! :-D I had assumed it was a typo...but was glad it was confirmed. I recopied the post with the corrected info...for my cheat sheet. Last evening my numbers looked like this:
FC 4.5
CC 0.2 ????
PH 7.5
CYA 30 (by testing)
I didn't add or do anything. I have a question about the CC test. Once the chlorine test is done and I add the 5 drops back to test for CC I am getting a color change from clear to a very light shade of pink (nothing like the pink is was prior)...just a tinge or hint of pink. One drop turns it back to clear...so in essence 0.5 CC. The 0.2 is sort of an interpolation based on the "slight" pink color...rather than the original "pink." Should I be considering my CC to be zero...or is the hint of pink normal, or is it showing there is a trace of CC?

Thanks! :-D
 
Just a hint of pink that goes away when you add one drop is called a CC reading of 0.5. CC at 0.5 or lower is fine, and fairly common in a spa. You only need to worry about it if it takes two drops to clear the pink when testing CC.
 
Even in my pool it is unusual to not see at least a hint of pink, but I use a 25 ml sample size and one drop is 0.2 ppm. If you are interested in seeing if you, too, have <= 0.2 ppm, then use a 25 ml sample size.

Having 0.5 ppm or less is fine. A spa tends to have a higher CC than a residential pool because the bather load is much, much higher in a spa. So there is a lot more sweat/urine to oxidize per water volume, though it usually does get handled before the next soak (i.e. within 24 hours), especially if the water is kept hot. However, if you were to use Dichlor-only and not switch to bleach, then the CYA level would build up and it would take the chlorine longer and longer to oxidize bather waste up to the point where you could find the CC rising and the water turning dull sooner. That won't happen if you switch to bleach so that the CYA won't continue to rise.

Richard
 
Richard,
Using a 25ml sample...do you still use the same number of drops as you would for the 10ml sample? Just the "value" per drop changes to 0.2. Is that correct?

Since joining TFP I have learned so much...and still learning. There is no telling what our CYA level was before. We used Dichlor every night, 1-2 oz. After a couple of weeks the water was just funky. And possibly unsanitized because the CYA was so elevated. Thanks again...

Travis :)
 
Dave,
Good Morning...and thanks for the confirmation! We actually start the ground work for our pool this morning. ...time to wake Kathy up! The ground is marked, sod cutter and tools waiting patiently for us to start the day. Since this is going to be a fully DIY install I will take pictures and start a new thread.

...I digress...Our spa feels and looks better than it ever has. It's actually nice to get out of it and not feel like you need to run to the nearest hose or shower.

Travis :)
 

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FlyboyTR said:
Using a 25ml sample...do you still use the same number of drops as you would for the 10ml sample? Just the "value" per drop changes to 0.2. Is that correct?
Click to expand...
Travis,

I'm not sure what you mean by using the same number of drops. If you are using a FAS-DPD chlorine test, you start out with scoops of DPD powder. Whereas you can sometimes get away with one scoop instead of two when using a 10 ml sample, you should generally use 2 scoops with a 25 ml sample for a crisp clear chlorine reading. With a 25 ml sample, each drop of FAS-DPD titrating reagent represents 0.2 ppm so at the same FC level you will end up using (and counting) more drops.

For an FC of 5 ppm, using a 10 ml sample would take 10 drops of FAS-DPD titrating reagent while using a 25 ml sample it would take 25 drops. This is why you usually use a 10 ml sample to save on reagent unless you have a specific reason for needing the greater accuracy, such as verifying that the CC is very, very low or for more accurately determining chlorine demand readings (such as overnight FC drop).

Richard
 
I really didn't make that very clear! :shock: I was confusing it with another test...thanks! For the 10ml does it really need to be a "heaping" spoon full? Does more give you a "better" reading?

We've been doing prep work all day on the pool. Took enough pictures to document well. We spent about 10 minutes in the hot tub and it was so nice... In over 4 years...this is the best water quality we have ever had. We're exhausted.

Richard...thanks again for catching the drops thing. Sincerely appreciated!

Travis & Kathy...
 
If you are using the "cup" end of the small scooper plastic "spoon", then it's just a fairly level scoop, not heaping. You don't use the larger flat end of the scooper (some people have made that mistake and used way too much DPD powder). However, you can pretty much tell how much because you want to see enough pink/red to give a reasonably strong transition during those last drops before it becomes clear. You can just use two scoops for the 10 ml as well as 25 ml samples if you aren't sure. It's better to use a little too much than too little -- mostly to see the clear transition at the end. If you use too little, you may underestimate the amount of chlorine by 1-2 drops.
 
I have been using the little spoon end. :goodjob: ...just slightly rounded above full. I will double that if using the 25cc mix. I can see where having a clear and almost instant change between colors it vital. Thanks again for the insight :-D
 
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