Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I have not seen this in either SMS or Turface.
I would test that in a series of buckets:
Turface + RO in one bucket
Driftwood + RO in another
Rocks (if there are any in the tank) + RO in another... and so on, until one of everything from the tank is being tested individually.
What fertilizers are you adding? What minerals and anything else?