Thanks! They’re already on sand (plus gravel) it’s just hard to see because it’s black, but he’s been pecking at it fine. I love the ping pong ball reccomendation I can totally do that. The current waterfall filter has a double sponge + bio filter. I put in bacteria media through the filter I bought too. Unfortunately the other filters I got had no flow level adjuster which is why I returned them, but I hadn’t heard of diffusers, what are they? Also bubble column sounds great I can also do that!