Shocking A Bromine Spa

[trigear]

What value in ppm would be an acceptable shock level for a bromine spa? If a mineral cartridge such as spa frog is used would that change the value?

[quantumchromodynamics]

10 ppm should be fine for a shock. Keep the cover open to allow any gases to get out. Silver is not compatible with bromine due to the low solubility of silver bromide.

Chem geek's rule of thumb regarding the addition of oxidizer is for every person-hour of soak time you need to add 3.5 teaspoons of dichlor or 5 fluid ounces of 6% unscented bleach or 7 teaspoons of 43% MPS. This can be helpful in determining the correct amount of oxidizer to add. If you have an ozonator, the amounts will generally be less.

The key thing is to maintain a consistent bromine level and to never allow the level to drop below 1.0 ppm. Test frequently and maintain a consistent 2 to 5 ppm.

Read waterbear's post on how to do bromine properly. Waterbear's post

I think that there should be a correction factor for the level of bromine and for the shock level for bromine due to the dimethylhydantoin concentration. DMH (Dimethylhydantoin) is the carrier chemical in bromine tabs similar to how cyanuric acid is the carrier in dichlor or trichlor. DMH builds up over time and reduces the reaction rate of bromine in a similar way to how cyanuric acid reduces the reaction rate of chlorine.

The problem is that we do not know the equilibrium constants to determine the correct ratios. I recommend that DMH be kept to less than 100 ppm (Others show 200 ppm). I recommend that the use of tabs be minimized and that the water be changed at least every 3 months. As the level of DMH increases, I recommend a slightly higher level of bromine and more frequent shocking.

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Note: Monobromamine is nearly as active as free bromine due to the presence of the monobromammonium ion.

NH₂Br + H⁺ < > NH₃Br⁺

The equilibrium constant is 3.2 x 10^-7 at 25^o C. pK = 6.49.

Reference 1

Reference 2