Chunks in my coolant

what you are witnessing is crystallization of the antifreeze from 2 sources . One : lack of use . Two : not using distilled water when you mixed antifreeze with water origionally . Tap water is too hard and has too many nasty chemicals in it .
DISTILLED WATER and 50/50 with antifreeze . don't buy the premixed crap . $8.00 per galloon for water . Duh !