We don't get many problems with mud but our May/June plankton bloom is something to behold, visibility can get down to a few inches all the way from the surface to 50 feet down. I've always ran my 798 in max mode and although this time of year it is tricky getting the right balance it's still possible to identify the stronger returns of target fish against the more general clutter. Finding shoals of baitfish like Sandeels is a totally different matter. Generally speaking I get rid of surface clutter, put the noise filter on medium and then adjust sensitivity so that I don't have a solid screen of returns - about 11-12 usually does me but that's salt water use in up to 60-70 feet of water. Either way I've never had a problem picking out fish 1-2lb+ against the general clutter. I'll post some pics up when I get a minute.
All the best,
Paul