Here is my ten gallon sand-bottom tank:
1 inch Home Depot play sand.
15 (or 18?) watt NO flo tube that comes with a 10g 12 hrs/day.
No ferts, CO2, or excel, only fish poo and snail poo.
Plants are baby swords (these plants are about.... 1 year old now) java moss, banana plants, aponogetons. Fish are 5 plumetail platies and one rasbora (which hid when I moved the original school out and was thus left behind.)
40% water changes (no gravel vacuuming) every other Saturday.
bastalker, it's prolly cuz you're so assertive with your gravel vacuuming that you've had no probs with the 3 inches of sand - that and the gravel
And yes, IME, planting is SOOO much easier in this sand. When I've removed plants from the tank, they've always got massive white root bunches.\
Oh yeah: this tank has never had any problems with algae.
A caveat, however: what is marketed as playsand in my local home depots may be very different than playsand from other such stores in the U.S. and may contain components that can affect pH or other factors.