Admitting Confusion After One Week

[Gosia]

Im taking sanitizing seriously, and am concerned that my dealer hasn't helped me get things right. I've been told to add dichlor or spa shock as a weekly shock or after a heavy use, but was set up with a bromine tab dispenser otherwise. My dealer helpe balance my water and was off saying I was fine for a week. I keep checking my water (with strips for now - I KNOW - I will buy a kit soon but Live in he middle of nowhere in Canada and hear things take time). My unease started when my test strips showed balanced ph and ta but no bromine? So I'm adding dichlor a tablespoon. How do I get the bromine tabs to work?

[chem geek]

How often are you in our spa (how many times per week), how many people soaking, and for how long? If you have your bromine tab dispenser turned up all the way, then you probably have a high bather load and that the bromine tab feeder won't be able to keep up. You'd have to add an oxidizer after each soak. If you soak every day or two, you might consider using Dichlor-then-bleach instead, unless you don't mind the smell of bromine. If you stick with bromine, make sure you have a bromide bank by adding sodium bromide after you did a fresh refill (or if you didn't do that earlier, you can do that now). See the stickies at the top of this forum section (Hot Tub Water Chemistry) on 3-step bromine and on Dichlor-then-bleach (in a nutshell).

[Gosia]

Thanks. I found those posts and they are starting to make sense (i must sound simple minded! But its a learning process with a lot of mixed messages from different sources).

We use our spa daily (2-4 people per day). I never added the bromine at fill up - only the dichlor. I will need to find a supplier of that since

MY dealer doesn't seem to use it. I think my dealer thought dichlor once as a shock and then the bromine tabs would work. He told me to check weekly ( I couldn't do with a clear conscience so I noticed the Low reading for bromine and kept dealing with it by adding the dichlor to sanitize).

Do you mean that bromine smells whereas chlorine doesn't? I'm tempted to transition to just dichlor then bleach ( who knows, maybe it will help my sons exczema). But like the idea of slow release pucks as a backup method too if we are away.

At the risk of sounding lazy, but really more curious about my dealers competence- if I stay the course and daily add dichlor and open up my bromi e dispenser - will I eventually have a bromine system - or do I still need to hunt down the bromine to add as a bank. Final question - what is an oxidizer? Is dichlor?

[chem geek]

Both smell, but they smell different (not only hypochlorous acid vs. hypobromous acid, but also the chloramines vs. bromamines which are more likely what you smell) and with chlorine you can start off with quite a low level before the soak and not smell much at all. With bromine, at least with tabs, it's trickier to vary the dose since it's designed to have a constant background level. That's great if you don't use the tub a lot, but since you use the tub every day you will probably be better off using Dichlor-then-bleach by simply dosing after every soak. Your water will last a long time that way (so you don't have to drain/refill as often) and you'll probably enjoy the soaks more. Anyway, you can try one method and then switch to the other to compare. Just note that while you can go from chlorine to bromine in the same water, to go from bromine to chlorine requires a drain/refill.

You are right that if you are away the bromine tabs act as a backup for dosing with sanitizer. Of course, you can always use Dichlor-then-bleach most of the time and then just put in a bromine tab feeder for when you are away. Just realize that from that point forward until your next refill, you will have mostly bromine in the tub even though you still use bleach (or initially Dichlor) as your oxidizer/sanitizer. It will oxidize any bromide left from the tablets back into bromine, though if only one week's worth it might end up outgassing all the bromine before your next refill (meaning you'll be back to a chlorine tub). None of this really matters unless you are trying to avoid one or the other.

As for your current situation, yes if you open up your bromine dispenser you will eventually have a bromine system because the spent bromine will remain as bromide so your addition of Dichlor (or bleach or MPS) will oxidize it back to bromine. So unless you really wanted to ensure a primarily bromine system right now, you don't need to create a bromide bank. As for the oxidizer, Dichlor, bleach or MPS will all do, though obviously bleach is the least expensive. However, since you don't have a bromide bank, I'd use Dichlor as your oxidizer for at least a week so that the chlorine isn't too strong. Without bromide to oxidize, the chlorine will last longer and be too strong without any CYA in the water built up from Dichlor, and that extra strength will be harsher on spa covers as well as on your skin, swimsuits, etc. Most will oxidize your bather waste, however, so it's not a huge deal -- I'm just being specific.

[Gosia]

This helps, thanks. I will stay the course and use dichlor for now (I've had the bromine p ucks in for a week only so maybe I'm not into bromine yet). Maybe until I get through more of my container and then switch to bleach to save money. Is the dose after bathing one to two teaspoons in general or per person?

[chem geek]

The dose is per person-hour, that is the number of people times how long they soak. With no ozonator, one person-hour of soaking in a hot (104ºF) tub requires around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS). This is just an estimate and you need to determine the actual amount such that you get at least a small residual chlorine level before your next soak. If your bather load changes, you scale proportionately.

[Gosia]

I'm sure we both thought that was it - i was going to rely on dichlor then bleach - but surprise, today my bromine was off the charts. We had guests yesterday so I shocked the spa ( with spa boss spa shock - no chemical label but dealer said it was chlorine). This must have oxidized too much bromide? My ph (6.5) and alkalinity (40ppm) were both low too (yes still no test kit - this is all strip talk) - so I now have the cover off, have taken outthe tab dispenser and have added ph raising product and alkalinity raising product and am waiting. In hindsight I think I should have done alkalinity first - but hope it all balances. So if it does and I'm seeing decent bromine levels, do I put the pucks back in and just oxidize with bleach if my daily bromine levels are low? And shock weekly or after heavy user load?

[Gosia]

Everything looks good today alkalinity and ph- balanced, good bromine level... What moves ph and alkalinity down? Is it as simple as dichlor being an acid? My spa shock chemical label says it does not affect ph - is it a different type of chlorine?

[chem geek]

Dichlor is roughly pH neutral when added, but chlorine usage/consumption is acidic so the NET effect of using Dichlor is acidic and that will lower TA over time. Whether it lowers pH or not depends on the TA level and aeration since carbon dioxide outgassing raises pH so can compensate for the drop from Dichlor. Also remember that bromine tabs are net acidic as well (and are acidic upon addition, somewhat similar to Trichlor tabs, though they dissolve much more slowly). If you ever use non-chlorine shock (MPS), then that is also acidic upon addition and net acidic upon usage.

[Gosia]

In a strange way I'm enjoying the chemistry of this. Thanks!