Rock Question

warpdrvr · Sep 23, 2019

So I was having a conversation with one of the LFS guys, and we got on the subject of how much rock is appropriate for a reef tank? He says that the "pound per gallon" is just out there so people have some sort of starting point in how much to have and it's not any kind of hard and fast rule. Me, I think I've seen that number around so much there must be some weight to it. Anyhow, I'm getting my 75 put together and have about 60lbs of rock ready to go at this point. I'm afraid to overdo the rock work and take swimming space away. So, what's everyone's take on the pound per gallon thing, and with 60lbs of rock and using about 2"+ of argonite sand, is that enough real estate for the bacteria to set up shop in my size tank?

MTBake · Sep 23, 2019

I feel that the lbs per gallon is over stated myself. I've seen anywhere from 2lbs per gallon to .75lbs per gallon recommended. Too much rock makes it difficult to aquascape.

I had as little as a fist sized rock in a 10 gallon tank along with enough sand to barely cover the bottom. No issues with ammonia, nitrites, or nitrates when I had that setup. It ran for just over 2 years with a pair of clowns and some mushroom corals.

lapin · Sep 23, 2019

Some rock weighs more than other rock. Then you have porous rock thats wet or dry. Some fish swim a lot and some dont. I would go with your 60. If it is too much put some in the sump. To little, add more. In my 600 I have 18 pieces that weighed 30 to 45 lbs a piece, dry. Lots of room for coral and lots of room for fish and inverts to play and sleep.

James77 · Sep 23, 2019

Pounds per gallon is about as useful as watts per gallon, just so many variables.

What kind of rock are you using? 60 pounds of dry reef saver rock is far different that man made live rock from concrete.

samnaz · Sep 23, 2019

For a 75 gallon, 60 pounds is plenty. You certainly don’t need a pound per gallon. That’s more of a general starting point, but IME it’s on the high end in terms of what’s actually necessary.

In fact, I have a 20 gallon with ~12 pounds of live rock and have for years. As far as I can tell it’s been a sufficient amount.