Two things come to mind...
First is...did you read the info at the Fox Farms website regarding the use of Ocean Forest? If not...do so now. (and then do a mini-flush) FoxFarm Soil & Fertilizer Company

The second is...those 'rocks' are the salts in the fert congealing. (clumping) Yes it does mean the nutes are getting old. But the salts start clumping at about 6 months after opening. I don't let that stop me fom using it though.

Shake very well before mixing the nutrients and flush the pots (1:1 pot volume:gallon of ph'd water) monthly to release those salts and prevent build-up.