How long to leave ozonotor running? Will it lower CC?

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Plumbdcrazy

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Mar 7, 2011
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I've got a 6473-125, Sundance Ozone, Corona Discharge, 240 Volt, 2000 ppm (250mg/h) in a 480 gal HT. The tub gets used at least once a day with the wife and I.

I'm using the BBB method as described on this forum and my numbers have all been in range (FC 3 PH 7.5 CH 200) using the K2006 test kit except I have a CYA of 60 (I assume its this high due to shocking with dichlor :hammer: ) and my CC is never under .5 and will jump to a 1. I've shocked and left one half of the cover open but it seems to have little effect. Besides picking up leaves. :)

Will running the ozonator longer have an effect on CC? It can be set to run from 1-24 hours.
how long should run it for?
how long before I see a lowering in CC? 12 24 36 hours?
Is .5 ppm of CC acceptable?

The HT is about 3 months old so i'm getting close to a refill along with a application of swirl away. maybe I just have a nastys issue? idunno

Thanks for any info/suggestions on this matter. :cheers:
 
(NOTE: This thread should probably be moved to the "Spas and Hot Tubs" forum)

Spas tend to record higher CC, especially in the hours after a soak. Are you measuring the CC just before your soak? It should be lowest at that time. Bather waste will combine with chlorine to form CC during and after the soak, but will eventually go away. And yes, an ozonator usually helps oxidize bather waste keeping the CC in check and also resulting in lower chlorine usage if you use the tub regularly such as you are doing. So try running the ozonator for a longer period of time. Roughly speaking, you can increase the ozonator time until your chlorine demand is roughly half of what it would be if you had no ozonator (i.e. no run time).

If you and your wife are using the tub for 30 minutes every day and if the tub is hot (104ºF), then this is one person-hour of soaking which would need roughly 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS) to oxidize the bather waste if there were no ozonator. So you can turn up your ozonator on time until the amount of chlorine you need gets cut down to roughly half these amounts. Note that using MPS will result in CC readings for some time after its addition.

You should not be using Dichlor-only if you want to prevent the CYA from rising. The higher CYA level will make the chlorine less effective having it be slower to oxidize bather waste and also be less effective for disinfection as well. I presume you have read the Pool School article Using Chlorine in a Spa.

Also note that if you didn't initially use Spa System Flush and/or do a decontamination when you first got your spa, then you could have biofilms as well as slow-to-oxidize organics in the water. The first fill for a new spa doesn't last as long because of these issues. You may have much better luck for your next water change. Some people have reported better results using Spa System Flush compared with Swirl Away.
 
Ozone will oxidize monochloramine to nitrate.

It's possible that the ozone is showing up in the CC test, especially if you're taking the sample near the bubbles. MPS will also show up in the CC test. You could try leaving the ozonator off for 24 hours to see if the CC resolves.

Your calcium at 200 is too high and could cause your heating element to scale up, overheat and fail. I suggest that you keep it closer to 100 ppm.

Your CSI should be slightly negative to prevent scaling. You can use the pool calculator to calculate your CSI.

Since your cyanuric acid is 60 ppm, you should stop using dichlor and switch to liquid chlorine (sodium hypochlorite). With a cyanuric acid of 60, you should keep your FC at about 4 to 5 ppm.

Doing a drain and clean would probably be a good idea.

Do you use MPS?
What is your current ozone run time?
What is your TA?
 
I normally check my spa every morning about 12 hrs after a 100F soak and on average i'll pour in 3-4 oz of bleach after a soak. I've been in the ballpark for FC so far. So it sounds like I'm not far off of the mark but I'll up the ozone cycle time.

Originally I thought I had a contamination issue and shocked with bleach with no change in CC so that's when I tried dichlor with the same results.

Thanks for the heads up on the Spa System Flush. I just ordered lamotte borax test strips and swirl away is all this supplier carried.

:cheers:

James
My ozonator isn't running at the test time but I'll remember that hint. I'm not using MPS anymore. I did initially before finding this site and that's been more than 3 weeks without MPS. :cheers:
TA-80 ozonator run time 6 hours but I have been all over the map with that number hoping to see a change in CC. From 24 to 4 hrs.

Looks like I'm due for a refill and a fresh start.
 
Since you have such a strong ozonator, it might be possible that the ozone is creating some oxidized products that could interfere with the CC test (possibly chlorate). You might want to try leaving the ozonator off for about 30 days to see what the chemistry does without ozone and then begin to gradually add ozone to see what effect it has.
 
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