Ok so I have had the titian moon sand in my 29 for 4months with 3corrys. They are doing fine. M khli loaches are fine too. But I just now go the white moon sand that is much finer, to put in my 10 gallon and plan to move the corrys to it purely cause I had too many bottom dwellers in the 29 and kuhli loaches shouldn't be mixed with the corrys because they will get to most of the food before the other guys have a chance.
Anyways I was amazed how much softer the white sand is and felt bad cause I knew just by feeling it my loached would love it to. I have the same problem I want black sand for my pirate scene in the 29. I then got on the Internet too look for softer black sand. Seems its impossible to find.
I guess if mix black and white that could work or you can get all Natural(no calcium or dyes added) Black Reptile bowrring sand. Two is 20lbs and the same price as the 1 bag of black natural 20lbs.
I did add 10lbs of this a month ago to my 29 just cause i only needed a little bit and the store only sells them in 20lbs. When I got the natural black sand for reptiles I realized it was much softer(still not as soft as the white for aquariums) but it had a lighter color to it. Like it wasn't a solid black. So if you don't mind that you could get 2-4 bags of natural reptile sand in black from pet co or petsmart and it may be better on belly's for bottom dwellers. Maybe not as much as the white sand but about a 20%-30% softness compared to titan moon sand.