I've now seen two people now on two different sites (both biased to sell a particular product) say that aeration and adding bacteria to a pond will eliminate bottom sludge even in an old pond.

I use both, but I say it should be used in the beginning to prevent sludge buildup and won't do a lot to thick sludge that is already there. Am I correct?

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.