Yeah, I have heard that if you keep tetras with GBRs you won't have any fry left, as the tetras move fster than the fry and/or parents. But a lot of sites are saying tetras are good tankmates for apistos, but hasn't mentioned if that holds true with fry, so i am confused.
I liked the idea of the sand because most sites are recommending fine gravel or sand for most all species of cichlids, and many other species as well. Plus I wonder if carpet plants would do better in it, and I think it looks better. But I did buy it for the fertilization thing... I'll have to think about this more. I do dose with weekly liquid ferts.
Personally, I'm liking the triple reds. I like the ones that have a slight bit of yellow and balck mixed in with the red (not sure what this is called). it's another reason I'm thinking of switching substrate, because that would mean red fish and red substrate, which I think would take away from the fish.