As far as I know what makes the Walstad method work is the Soil Substrate.
Color Quartz is Inert and probably won't retain any nutrients at all. It way work but you may have to dose more to accomplish your needs.
Hi Craig, thanks - yep, I assume this as well. I'm drawing something from Tom Barr on this:
Originally Posted by Tom Barr
Soil substrates are popular with non CO2 users and they work well but peter out after about 6-12 months. They help the plants get established initailly abnd supply nutrients that are other wise lacking in the beginning before many fish are added and the tank has had a chance to accumulate waste.
So, making a couple of assumptions (and I might be completely off - so all thoughts appreciated):
1. Plants derive nutrition from anywhere it's supplied. Different plants "prefer" nutrition from different places - e.g., crypts tend to be deep root feeders, so will more easily draw nutrient needs from enriched substrate than from strict water column dosing.
2. That said, all plants thrive so long as they receive proper nutrition, whether from water column, soil, or both. They will grab up what they need.
3. Since I am using no soil, and only quartz substrate, going with mostly rhizome-based plants makes sense, on a presumption they will require less energy to draw nutrition into their roots (their rhizomes exposed to the water column).
4. I am not depending solely on fish load for ferts, but dosing according to what I can derive from Tom Barr's recommendations for a non-CO2, low light system, adding back in some carbon with a daily Excel dosing of 1ml/10 gallons.
These are my (newbie) presumptions - and I freely admit I may be totally off base. Hoping just to create a very low maintenance tank, in distinction to my other tank, for now.
Edited to add: Given my inert substrate, maybe a higher dose regime for several months, then pull it back - presuming this will help plants establish their root systems, etc.?