Rockwool cube in expanded clay

hi buddy, they seem to be fine apart from that light yellow which means you are not wetting the walls with enough EC solution, nothing serious less and less that you remember too. In this phase it is sufficient to wet 1 rock wall with about 70ml of solution at PH 5.9-6.0 and ec 700-900 ms / cm depending on how they react, it is also very important to favor evaporation from the rock wall. and don't leave it "soaked" all the time. must dry a minimum. a greeting good luck!