should I Measure Total Chlorine?

[999]

I have more or less decided that i am going to try dichlor as a sanitizer when i change the water soon (from bromine).

I currently us test strips that measure free chlorine/bromine, alkalinity, PH and water hardness.

I am due to buy some new test strips and see that they also do a strip that tests for Total Chlorine as well as the other four things.

Do i need to measure total Chlorine if using dichlor as my sanitizer. If so why?

[chem geek]

Do yourself a favor and get the Taylor K-2006 test kit.  It is much more accurate than test strips (see this post for more details).  You do measure Combined Chlorine (CC) in addition to Free Chlorine (FC), but in a properly maintained pool or spa you will find the CC level to be very low if you measure before your soak (it goes up during and right after your soak, but then drops back down within 24 hours).

Note that if you have an ozonator but do not soak frequently (i.e. less than twice a week), that the ozone will react with chlorine increasing chlorine demand.  You will need to add chlorine every day or two in that case, maybe twice a week if you add more.  On the other hand, if you are using the spa frequently, every day or two, then an ozonator will help to oxidize bather waste and lower chlorine demand.  Such high usage also works well with chlorine since you just add it right after your soak such that you have at least 1-2 ppm FC measured just before your next soak.

You might consider using the Dichlor-then-bleach method if you want your water to last about twice as long and have less risk for disinfection problems, but you would probably need to get your Total Alkalinity (TA) lower, perhaps down to 50 ppm, and would need to use 50 ppm Borates such as in Proteam Gentle Spa or a boric acid product or a combination of 20 Mule Team Borax and Muriatic Acid (or dry acid but that increases sulfates).

Why are you wanting to switch away from using bromine?

[999]

I do have an ozonator and would say that we use the hot tub about three times per week. The only problem, is that I work shifts and may not use it for 3-4 days, then I will use it for 3 days in a row.

I am considering changing from bromine (slow disolving in floating dispenser) to dichlor because I am not that keen on the smell, it seems to be quite choaking when it is cold and there is a lot of steam. I also find that when i use non chlorine shock the bromine levels go up really high. The last time I shocked it, it took 4 days to come down. I am maintaining a constant level of 4-6 ppm and feel that I am stewing in chemicals when I use it. I have never had a problem with bromine, the water is crystal clear and I adjust the alkalinity upward about every 10 days. With dichlor, I like the thought of there not being much chlorine in the water when I use it, and adding it afterwards. Providing I keep the chloramines down with shocking, then it shouldn't smell too much either.

I have had my Jacuzzi hot tub for three months and would prefer to stick with their branded products, so don't want to use bleach at all. This is not something that is widely used in the UK, and I am keen to only use what is recommended for the warranty.

[chem geek]

OK, just keep in mind that for every 10 ppm Free Chlorine (FC) added by Dichlor, it also increases Cyanuric Acid (CYA) by 9 ppm.  Higher CYA levels lower the active chlorine level so over time you get less disinfection and oxidation so generally have to change the water sooner than if you were managing the CYA level by using bleach after you have built up Dichlor (plus a once-a month touch-up of Dichlor since the CYA slowly drops around 5 ppm per month).