Our seals failed the first year. I had used 2000 Flushes in the tanks of every home we had since 2000 Flushes hit the market, with no problems and great results. Then we find out that the seals in the tanks are different in TV (maybe everywhere, because our last house was built in 1997) and the chlorine in 2000 Flushes erodes the seal.
We had multiple cats living to be 17 and 20 on 2000 Flushes potty bowl water (what can I say) , but a seal fails in a year???
One thing that helped prevent the ring in the guest room bathroom john was leaving the top lid open at all times and flushing the john daily... which I took care of because that bathroom was closer to the living room than the mbr bathroom.