Chlorine Sanitized Tub, Bromine Tabs added

[JVTrain]

So I have been keeping my spa sanitized using CYA/Chlorine for several months. I've kept it in check, had to perform a quick SLAM on it once after I was gone for a bit and things went south. Not bad, just enough that FC went to 0, SLAM for a day, back to normal.

Since then, kids have used it alot to warm up on cool days and lots of splash out/refilling despite my protests. CYA now down to likely 10 or so. Won't register on TF-100 test (mostly clear to the top). While I was gone this time, 2 1" bromine tabs got added to the skimmer cup above the filter. They are fully dissolved. After hearing this had happened while I was gone, I had my family add enough bleach to hit presumably 12 FC. My wife tested later in the day after more use. FC at 0. She then added enough to get it back to 12 FC. I arrived home several hours later (not sure if it was used much during this time) and FC was 0.5, CC 1.5. I then added enough to get back to 12 FC, tested 30 minutes later and FC 2, CC 3. Cleaned the filter and testing/dosing again shortly.

The question I have is... is it now a bromine tub and do I need to get a bromine bank in there, then continue with a SLAM or is it still a chlorine tub and should I continue with SLAM?

Water is slightly cloudy (I'm fussy, so not much). What I'm worried about is that if it is now a bromine tub, there isn't enough bromine in there to properly sanitize even if I continue with using bleach to refresh the very small amount of bromine.

I'll do some more reading on the bromine sanitation sticky to see if I can figure it out but any pointers would be appreciated. I am going to drain, deep clean, flush the tub in the next month or so anyway just to start fresh. Maybe I should move it up and start with chlorine again...

 

[JVTrain]

Just tested again.

FAS-DPD Drop test
FC 4.5
CC 2.5

K-1000 Color Test
FC/TB - ~3/6
pH - 7.5

Added enough bleach to get back to 12 FC target.

Last full other test results from Saturday:

CH 275
TA 60
CYA <30 (likely 10-15 based on amount of water replacements between when it was 30 and now)
No borates
95 degrees F

 

[chem geek]

Once you've added bromine to the tub, it's a bromine tub until the next refill. Unless the amount of bromine added was very small, but given 2 1" bromine tabs that's probably over 30 ppm bromine cumulatively. You should be able to add an oxidizer, such as chlorine bleach, and produce more bromine from the bromide bank that was created when the bromine from the tabs got used up.

 

[JVTrain]

Alright. Thanks for the tips. Not much info here in Pool School about Bromine products so I'll do my own research on what's in each tablet (left from previous owners and put in tub by *ahem* my extended family) and work on putting the bromine spa sanitation sticky to memory. It'll at least give me a perspective on using bromine for sanitation to see if I prefer it to CYA/chlorine before the next drain/refill process.

 

[chem geek]

They are likely BCDMH tablets which have bromine and chlorine but the net effect is bromine because the chlorine just activates any leftover bromide. When the bromine gets used/consumed, it reverts to bromide. You can read more about bromine in the Pool School - Further Reading - Using Bromine in a Spa thread. You probably already have a sufficient bromide bank from the two bromine tablets. If in doubt and you decide you prefer bromine over chlorine, you can buy some additional sodium bromide.

 

[JVTrain]

Yep. 98% Bromochloro-5,5-dimethylhydantoin http://www.proteampoolcare.com/images/uploads/BROMINATING_TABLETS.pdf I have about 3 lbs left of the original 4 lb pail I inherited.

From the sticky thread it suggests adding 6 tablets to achieve a bromide reserve. Should I add 4 more 1" tabs over the next week, then stop using tabs and only continue to oxidize bromide to bromine as needed with bleach? My other option is to put tabs continuously in a floater and shoxidize (haha, sorry couldn't resist) weekly.

I have an ozonator but the wiring on it is damaged from previous owner, so I have it disconnected.

 

[chem geek]

Yes, you can use tablets as your bromine source until you use them up and after that you can then use bleach to activate the bromide to bromine.