Amount of rock

[Jon Fishman]

I keep reading (and have adhered to) the "at least 1lb of Rock per gallon" rule and It always bugged me. If I have a 100 gallon tank, and put a 100lb rock in it, there is no way it would have the filtration/surface area/bugs that 5-7 10lb rocks would have.

I know nobody is really doing this, but I would think rocks that were lighter (very small rocks that float a-la Monty Python. Hahah) or more branch-like rocks etc would require less weight, and it would be all about surface area.

I am shooting for the "you can't have too much" approach, but these are just the thoughts I keep having when reading about rocks.

 

[rsumner]

IMO, the 1lb/gal rule applies when you intend on using rock as your primary mechanical filtration. If you intend on having a sump with socks (or other mechanical filtration), the need for so much rock for filtration simply doesn't apply. When I setup my Red Sea 525XL (108G 5ft tank) over 14 months ago, I bought 110lbs of rock. By the time I was finished aquascaping, I had nearly 1/2 of it left. I bought fairly expensive Walt Smith Project Reef Rock and have had a whole box of it sitting in my garage for over a year now. I look back at my tank now and I actually want to remove some of the rock to increase flow and provide just a little more swimming space for the fish.

My advice, if you have a sump and want a simple-to-moderate aquascape, is to buy 1/2lb per pound.

 

[PatW]

Live rock’s primary purpose is to provide a scaffolding for bacteria. The bacteria converts toxic ammonia from fish waste into nearly non toxic nitrates. The amount of rock you need depends on your fish population and how lavishly you feed. If you have a small fish population that you feed sparingly, you will not need that much rock.

The more porous the rock, the less weight you need.

Also if you have some rubble in your sump, you will need less rock.

People are trending to minimalist aquascapes. These run about .5 lbs per gallon or less.

 

[norfolkgarden]

Ideally your rock looks similar to the picture. Any type of clean mined riddled limestone or old coral skeletons should be ok.
Lots of people have raved about some of the Florida live rock.

I'm sure you know you are not looking for granite or anything similar. [emoji846]

One of the main concerns is what type of fish you plan on putting in your tank.

For fish that spend their entire lives searching live rock for food or grazing, the more live rock the better. It is similar to captive foraging for parrots.
Even though nearly all the food comes from you, it gives them something to do in a more natural setting.

If your primary interest is corals and you only plan on adding a lawn mower blenny and a 6 line then you have a little more flexibility.

It is also a personal preference.

I scape my tank to represent what I enjoyed seeing scuba diving.

As a personal preference, the empty tanks don't do a lot for me.
I keep hoping that is just a passing fad and will go away in a decade or so.