Originally Posted by waterbear
There is a lot of misinformation on the proper way to use Bromine so I hope this primer is helpful.
First, you need to establish a bromide reserve in the water. Bromine tablets can do it by themselves but it can take literally weeks until enough dissolves. Some people crush about 6 of them up and put them in the water on each water change to achieve this but it really is easier and cheaper to add a packet or two of sodium bromide! It is available from such companies as HTH, Leisure Time, Robarb (Rendezvous) and others. Bromine tablets contain both bromine and chlorine to oxidize the bromine into active sanitizer. (There is one that I know of on the market that contains MPS instead of chlorine but it works exactly the same way.) If you do not add the sodium bromide and just put in bromine tabs then you will be starting with a chlorine system until enough bromide dissolves in the water.
There are basically two ways to do a bromine system--2-step and 3-step. In the 2-step system you add the sodium bromide to the water to the proper concentration, then add oxidizer on a regular basis (usually chlorine, MPS or ozone or a combination of them) to oxidize the bromide ions into hypobromous acid, your active sanitizer. It's pretty easy but does require a bit of attention daily to maintain the bromine levels in the water.
A 3-step system is identical with the addition of bromine tabs in a floater. This will help maintain a more constant bromine level in the water with less maintenance but otherwise there is no difference. The 3-step system costs more since the bromine tablets are the most expensive part of this equation. The dimethylhydantoin in the tablets seems to have a similar (but not identical) function in a bromine system as CYA does in a chlorine system. It tends to stablilize it but, like CYA, too much is not good. Not that much info is readily available on the effects of dimethylhydantion other than that it makes the bromine more difficult to destroy, a consideration if you ever want to switch over to a chlorine system.
If you add sodium bromide to your water and have an ozonator you might be able to achieve the constant bromine level without the floater since the ozone is constantly oxidizing the bromide while it is on. However, you might deplete the bromide reserve quickly this way, leading to a shorter time between drain and refills. Also, ozone can cause bromates to form in your water. Bromates are a suspected carcinogen in drinking water.
You still need to superoxidize (shock), usually about once a week to destroy organics in the water whether you choose the 2-step or 3-step method.. I prefer plain, unscented laundry bleach (5.25%) for shocking a bromine spa. 1 cup per 250-300 gallons is about right. If you use Ultra bleach (6%) then you need about 3/4 cup. You can also use 12.5% pool chlorine at half the ultra bleach dose. They are all sodium hypochlorite, just in different strengths. If you do not want to use a liquid shock you can also use calcium hypochlorite granules (slow dissolving and will cause your calcium levels to rise), Lithium hypochlorite (very fast dissolving but very expensive, however my first choice for a granulated shock since it really has minimal impact on your water just like the liquid does), or MPS--potassium monopersulfate, also called non chlorine shock (will lower your pH and TA and add sulfates to your water). There is no advantage to using dichlor (stabilized chlorine) for shocking a bromine system but it probably wouldn't hurt. CYA (stabilizer) does not stabilize bromine.
Here is a step by step:
1) On each fill balance the water (adjust TA and pH. Add calcium if below 125 for acrylic spas or below 200 for plaster). More info here on balancing spa TA and PH, How do I use Chlorine in my Spa (or pool)?. If you have metals in your water add a metal sequesterant.
2) On each fill add sodium bromide to the water. (Follow manufacturer's directions on dosing. You will end up with about a 30 ppm concentration of sodium bromide.)
3) Shock with your preferred oxidizer (chlorine/bleach or MPS) and turn on the ozone if you are using it. Your bromine levels should now be above 10 ppm. Wait until they drop below 10 ppm before entering spa.
4) If using a 3-step system add your floater with bromine tabs and adjust it to maintain a 4-6 ppm bromine level. If using a 2-step system add your preferred oxidizer as needed (and adjust your ozone) to maintain a 4-6 ppm bromine level.
5) Shock weekly to burn off organics that collect in the water. (If you are using ozone and your bromine levels are staying at 4-6 ppm then you can shock less often.) Wait until the bromine level drops below 10 ppm before entering spa.
6) Test bromine and pH before entering spa each time. Test all water parameters (bromine, pH, TA, Calcium Hardness) weekly.
7) Drain and refill about every 3-4 months.
One final note. A good test kit is a must, just like with a chlorine system. IMHO, the BEST test kit for bromine is the Taylor K-2106 which has an FAS-DPD test for bromine and also tests for pH with acid and base demand, TA, and CH. If you already have a Trouble Free Testkit TF-100 (or are getting one for your chlorine pool) then use the OTO test (small comparator with yellow color blocks) for your bromine levels since you only want to know total bromine. The TF-100 has all the other tests you need also. Remember, you don't need to test CYA in a bromine system.
Happy bromine hot tubbing!