yes the clumps are presipitated nutrients. This is not good. it locks up those nutrients and you are depriving your plants of them and worse is you are locking up the plants also. because you are now using to much of the nutrients that have not presipitated together in your nutrient solution. It happens all the time if you do not store your nutrients properly or with age as stated. I still use the locked up nutrients just not on these plants. use them in the garden and get yourself new nutrient solutions, so you are positive that the plants are getting a full balance of nutrient.