the sales person in the petsmart encouraged me to do exactly the opposite of what I should have done...
"Throw the fish in 5 min after starting the filter. No cycling, change the water about once in 4 months..."
...and come back for medicine when your fish gets sick... and come back for another fish when yours dies.
Sheesh. Well, you'll get mostly very good advice here. If
you get any bad advice it is likely that another member will spot it and correct it. I can't help you with DSM myself. As for substrates, I am not sure if you mean ones to work with DSM specifically. If you mean generally, there are many good approaches. I would not suggest one over another without knowing what you want to get out of it. They all have their pros and cons. Some are low maintainance, some are high production, others are self sustaining, and some are as expensive as hell. If you did mineralized soil capped with sand I could help a little. I run a bare bottom now because I keep goldfish in it and their waste is unbelieveable. Ease of cleaning is what I want/need most for this tank. The plants are tied to big chunks of driftwood, so I can arrange them in different layouts every day if I feel like it. If I wanted a beautiful high light aquascape complete with a rolling green grasslike "lawn" I would have a very different substrate. Anyway, it is nice to have you in the forum.