Snyper...I hesitate to say this but I am 3 1/2 weeks and going and still my water is beautiful. I think I told you that my plan now is to test and shock before I adjust my bromine cartridge. If we all jump in (2 kids, 2 adults), I may hit the tub with a tablespoon of shock when we get out and the tub goes into a clean cycle. This is in a ddition to shocking when I see the bromine level dip or drop completely. This method is very un-scientific, but so far it is working. My bromine levels are low AND I still have bromine in my cartridge after 3 1/2 weeks. Markee, I have another bromine frog cartridge question for you ...My spa monitor and the control panel are saying rsa to check my sanitizer. I did and there is still plenty of bromine in the container (when I shake, it comes out), so do I continue to ignore the reminder until I put in a new cartridge or do I reset now even though I still have bromine? When I reset the reminder will it remind me again in 3 weeks from the date that I reset it..or is that in some sort of internal memory that will again remind me 3 weeks based on the first cartridge that I put in? I hope you can understand that question....Or if I am finding that my cartridges now last longer because I am shocking more often, can I change the sanitizer reminder to 4 weeks instead of 3? If the new cartridges last longer, won't we have to do that anyway?