Clean up crew too early?

[cactuspat]

I have a 20l that has been running for about a month and a half. 0-0-less than 20 across the board with 1 small fish. Is it too soon to add that many? There is some light brown algae on parts of the sand and some of the surface of the rocks higher up. I was looking at a 10g quick crew possibly to start things off.

[johnmaloney]

if the diatoms are started and the tank is cycled it is safe to add them, but you are in no rush