i see some people with a 3 baffle setup in their sumps.. after the overflow line there is the first baffle, which is of course to force bubbles or whatever might find its way there.. up
and then the 2nd that is an inch or so up above the bottom of the tank to stop bubbles or whatever... from passing by and finding their way either to the skimmer or return pump or whatever you may have
but i see some with a 3rd, that is also against the bottom like the first ..... whats the purpose of it? to stop things from maybe making their way back across somehow?
id like to know before i add mine to my sump / fuge so i can get it all done at the same time if i find out i like the 3 idea