If you have not already done so, you can create a bromide bank by adding 1/2 ounce of sodium bromide product per 100 gallons. After that, you can use any oxidizer (chlorine, non-chlorine shock MPS) to create more bromine. Even an ozonator will create bromine from the bromide bank. If you don't have an ozonator, then using chlorine periodically (say, once a week) to shock the spa to produce more bromine will help keep the water clear since chlorine can oxidize some chemicals that bromine doesn't.
Remember that your bromine tabs are designed to output enough bromine to keep the level stable in between soaks -- you set the vanes so that this happens. However, unless you are just one person soaking for a very short time (15 minutes or less), then the tabs will not likely keep up with your bather load and you need to add an oxidizer (chlorine, MPS) after each soak (especially if you don't have an ozonator).