Originally Posted by Arvo
With a sufficient topping to the peat - 3+" - the water did not noticably discolor.
That must be the difference.
The first tank I did was an existing setup. I couldn't get it really well-drained, so, as I mixed things and built the top layer, stuff tended to migrate upward, with the cap being about 2". The second setup was new, and I made it with almost 3-1/2" cap over the enriched part. No real discoloration in that second tank.