How much live rock for 20 gal tank?

[deathwater]

I want to mix Fiji with som Kaileni but I want to try to figure out how much I need by the pound instead of just filling it up to the point I would like it.

[Aquarist007]

about a pound and a half per gallon
So 30 lbs would be great

[1fishkeeper]

A good rule of thumb is 1 1/2lbs per gallon. I know some people only do about 1lb per gallon and get away with it. But just remember that your bio filter is on the rocks. The more area there is the larger your bio filter will be. Myself I have kaileni rock in my 29gal and I have close to about 35lbs of it in there along with about 10lbs of fiji in my sump.

[reefworm]

1fishkeeper is correct - surface area is the key, so weight is only part of the picture. really porous means less weight needed. i had close on 40# in the 29 back in the day, but with the rebuild I'm leaving more room for flow and coral grow out, so I've got about 25# of very porous rock in the display and maybe another 5# in the sump