Need help with spa water chemistry

[ARSayeed]

The spa is on a separate system than the pool (heater and filter) and the heater is almost always on to keep the temp at 101-104. Since I found TFP, I have been using BBB to maintain the spa but its been a challenge keeping the FC levels up. Before I left for a quick business trip, I put 3" chlorine tablets in a floating chlorinator because I knew the chlorine levels wouldn't hold while I was gone. When I did the FC, CC, TC test tonight with the TFT100, I'm getting very weird results - when I put the R-0003 in, the water immediately turned a dark brown (never happened before). When I put the R-0871 in, the color did not go back to clear. Here's a set of full test results:

FC = 0
CC = ?
TC = ?
PH = 6.8 or lower
TA = color never turned red after a lot of drops. Very light green when I added R-0008.
CYA = 100 (below the 100 line)
CH = 450? The color turned clear and never went to blue

Do I need to just drain it and start over? What is the best method to keep water balanced in a spa that is always hot?

 

[jblizzle]

You CYA is way too high, so that might be reason enough to start over.

I too am confused by your CC result ... never heard of it turning brown.
What color does the OTO test turn?

 

[ARSayeed]

I don't know what the OTO test is? Is that the overnight FC loss test? I've been testing the pool and spa for a long time and that has never happened before with the CCs. I did the test 3 times just to make sure I wasn't doing something wrong.

 

[jblizzle]

OTO is the yellow chlorine test that is next to the pH test.

 

[ARSayeed]

I didn't check that one. I just did the test in the TFT100 kit with the the powder and the R-0871 + R-0003.

 

[ARSayeed]

Ok I drained the spa and have refilled it after cleaning it out.

Test results are:
FC = 5.5
CC = 4
TC = 9.5
TA = 80
CH = 140
PH = 8.2+
CYA = 20 (can still see dot with tube completely full)

I'm planning on bringing up the CYA and CH. lowering PH to 7.5 and then begin the shock process to get rid of the CCs. Anything I'm missing?

Also, the spa heater is always on and the temp is 102-104. Is the BBB method still the best for a spa or is there another way to keep chlorine up in the high temp water?

Thanks for your help!

 

[linen]

I use the dichlor then bleach approach discussed here: http://www.troublefreepool.com/how-do-i-use-chlorine-in-my-spa-or-pool-t10095.html. It works great for me. I sounds like you were using trichlor as you primary source of chlorine (or dichlor for that matter?)?...imo that is a recipe for disaster in a chlorinated tub.

 

[linen]

Oh I just saw you put the trichlor in when you went on a trip. How much trichlor and how big is your tub? One 3 in (8 ounce typically) puck will add 67 ppm cya and raise your FC to 110 in a 500 gallon tub. I would guess the brown you saw was due to very high chlorine levels.

Do you know your cya level before adding the trichlor?
How much use doe the tub get?
How often are you changing the water?
Are trips where no one can add bleach to the tub a normal occurrence?

 

[ARSayeed]

Actually you are right, I was using trichlor on a regular basis. I switched to BBB in May after I found TFP. I just put the tabs back in when I left for a 2 day business trip. Wow! I didn't realize how much CYA was added with such a small amount of trichlor. I was definitely over chlorinating.

Answers to your questions
CYA level before adding trichlor for my trip was 70
Everyday use
Not changing the water often. Adding water everyday with use, evaporation and a small leak.
I travel fairly regularly but someone can add bleach if needed.

There is an auto chlorinator on the system for 3" pucks. I haven't used it except for 1 season of the 4 we've lived here. Mainly because it would add too much chlorine no matter how low the setting. Is there a device that can add bleach or chlorine to the spa regularly in case I'm not here?

 

[chem geek]

Is there a device that can add bleach or chlorine to the spa regularly in case I'm not here?

No, not unless you get a peristaltic pump similar to what is done with pools, but that seems like overkill. The other option is to use a saltwater chlorine generator such as the ControlOMatic Technichlor, but that requires 2000 ppm salt in the spa and would be something to do if you wanted to switch to that method completely rather than just for vacations.

You could put in bromine tabs into a feeder, but that would turn your spa into a bromine spa until the next water change. You could still use bleach when you got back, but you'd have bromine in the water until perhaps it all outgassed depending on how much was added when you were gone.

If you are only gone for a few days or even a week, you can just shock the spa with a higher chlorine level and lower the water temperature and of course keep the spa tightly covered (no sun and minimal air circulation). You should easily be able to have the chlorine last for up to one week if the water temp is cooler. If you had 15% chlorine loss per day, then starting with 10 ppm FC would end up at 3.2 ppm FC at the end of the week. This assumes, of course, that you have no ozonator. With an ozonator, this won't work since you lose 50% of the chlorine per day with an ozonator in a hot spa so I'd figure you'd still lose way too much even at cooler temperatures. If you lost 25% per day, then after a week you'd go from 10 to 1.3 ppm FC which starts to get risky. Losing 40% per day, you go from 10 to 0.3 ppm so likely to get to near zero which could let bacteria start to grow and biofilms form.

 

[ARSayeed]

Thanks everyone for the helpful responses!