parttimer

I recently picked up a used Jacuzzi tub and got it set up. I did not know about the bromide reserve and filed the tub, added the metal remover, dropped my floater in with tabs and added bromine crystals. That night I tested, and needed to lower my PH a tad to get in the 7.5 range, bromine levels were at about 5, and everything else was ok. We used the tub, and I checked the next morning, bromine was at zero. That night I added bromine again, waited about 1/2 hour, tested at a 6 and we used the tub. Seems like I was doing this process every day. Then I read about the reserve and adding bromide. I picked up 4 packets of HTH bromstart, added 2 of them, figuring my tub to be about 350 gallons. I checked the next day, nada, so i added bromine. I have been going back and forth with this for a week now. I even added another 2 packs of the brom start. I assume I am missing something since the bromide is not converting. I will say my house water is filtered to remove chlorine and other chemicals so I have pretty clean water. So what am I missing so I am not adding chems each day to the tub??