I was always under the impression that chunks were bad in the nutes.
Chunks are bad. Definitely not good in hydroponics. If it's in Deep Water Culture, not the end of the world, but anything that needs a water pump is going to have trouble with chunks - they'll either clog up the filter, the pump, or both.
Plus, the chunks are indicative of a bigger problem - the nutrients are becoming solid rather than liquid and plants can only absorb them in liquid form.
The guy at the store really pushed them over Advanced stuff. And it was a bit cheaper so i figured that he was telling the truth.
You've got to take what the shop guys say with a grain of salt. They may be pushing a cheaper product but that doesn't mean they're being more honest. Simply because something has a bigger number on the sticker doesn't mean the shop makes more money selling it. If the $20 bottle costs them $19 to stock and the $15 bottle cost them $13, they make twice as much profit pushing the cheaper bottle.
You've got to go with a more disinterested party if you want an honest opinion.
I've never had any trouble with Advanced Nutrients - no chunks or anything silly like that.