Welcome to our forum.
Obviously, as the tub is used, the sanitation is being burnt off, which means topping up with more chemicals.What happens after a number of weeks.Whilst i can understand them losing effectiveness, i find it hard to believe that they are just disappearing.We switched from Chlorine to Bromine a few fills ago.I'm about 10 weeks in to this tub full of water, so it's due a change anyway.At the weekend, the wife came out with a rash, much like bug bites, which it seems (googling) is quite common for Bromine.10 weeks or so of dumping 2 tablespoons of bromine, and PH+ etc must be doing something to the water surely. ?I might add that we were entertaining for the evening and were in about 5 hours... oops
We switched to Bromine about 2 or 3 fills ago, as neither of us like the smell of chlorine.I check the water using strips weekly, and always definitely before we get in, so at weekends it's checked Friday, Saturday and sometime Sunday.I shock using MPS weekly.I can concur with Tman's sluggish bubbles, these have been becoming more sluggish over time, to the point where i felt on Saturday that adding anti foam no longer worked.Saturday night was quite a heavy bather load, 4 of us for 4 or 5 hours, so I changed the water on Sunday, and switched back to chlorine.I think maybe, i might just change the water with more frequency, maybe every 4-6 weeks.My only issue, without a submersible pump, it's a 7 hour job.