How to recycle my old substrate and add new substrate
I'm planning to upgrade my tank from a 90Cm to a 150CM tank. I plan to use my existing gravel which is a mixture of Amazonia Gravel , Small Pebble Stone gravel and black sand.
After watching ADA videos i'm interested to add those additive like ADA Penac W, ADA Penac P and ADA Tourmaline into my new 150CM system.
So my question is can i use my current mixed substrate as a bottom layer gravel then add on those additive before laying another new layer of amazonia gravel.