dc_homeplumber said:
Fluidmaster now makes an in-tank bleaching system that sends the chemical down the overflow tube of the flush valve directly into the bowl so that the chemical doesn't come in contact with tank components. I've seen it at The Home Depot for about $15.00. I'm not sure how much the replacement bleach cartridges are.
I tried one of these and didn't like it. I think its poorly engineered. The system can be purchased with either a blue cartridge or a clear bleach cartridge. Same system, different cartridges. I bought the sytem that came with a blue cartridge, so I could see the results. The system dispenses the chemical directly into the bowl, so it doesn't touch the parts inside the tank.
Results: Well, the chemical is released into the bowl at the start of the flush, and goes directly down the drain! Hardly any is left to sit in the bowl and do the work. Of course you won't notice this with the clear bleach cartridges.
In summary I feel that this product was a complete waste of money. YMMV.