Help with cloudy hot tub

[JJH1111]

We have had the hot tub for about two years. I guess I really don’t know exactly what to do. We set the frog at 4 and change it every three weeks. This kind of works, but the tub goes cloudy often. Looks like I need to shock the tub, but not sure exactly how to do it. We do the TFP system on the main pool with spectacular results.

It is a Marquis fiberglass 500 gallon hot tub. We use the Frog 1-Bromo-3Chloro-5-Dimethylhydanion inline feeder. (see photo) I think this is the BCDMH brominator in the taylor book. Is this the 2 step or three step system? Should I abandon this system?

Test results for taylor 2006 kit
FAS-DPD test 25ml, two scoops R-0870 powder. 40 drops to clear *.2 = 8.0
CC = 1.6 – can I test combined chlorine with bromine ?
pH = 8.0 – high
CH = 260
Alk = 180

I am thinking of shocking with 12% pool shock, and adding dry acid to lower the pH.

Thanks for the help.

 

[Donldson]

DMH in the bromine tabs builds up similar to CYA and buffers the effectiveness of bromine. Unfortunately, there's not an easy way to test for it.

How long has it been since your last water replacement?

 

[JJH1111]

We filled the tub April 8th, so about 2 months ago. Can I do a CYA test on hot tub water?

 

[Donldson]

It's not CYA, it's DMH. Like I said, there's no easy way to test for it.

I would just dump it and start over. At 500 gallons it's not really worth the trouble of trying to fix and 2 months is not an unrealistic refill interval for a hot tub using bromine tablets.