Quote Originally Posted by Bree1978
^ IA. H2O2 is for algae. I've considered reasonings to this predicament recently because I got it too. I'm guessing it is soil dust/debris that has 'baked' onto the pearlite after watering.

:jointsmile: Bree
I agree, mine's turned a bit yellow too..is definitely just stuff from soil...it's happened on previous times too for me.