weight versus volume of live rock

[unckeyherb]

So this may be a stupid question, but I currently have a 48"x24"x30" 150 gallon freshwater that I am thinking of converting to a reef tank with fish. After doing some research at a couple of LFS' the cost of live rock varies from $5 to $7 per pound. I have heard that you should use +/- 1 pound per gallon. My question is: How large is typical Fiji Rock per pound (or maybe easier to answer is how heavy is a cubic foot of live rock). Obviously this is a rough number and is dependent on how porous or dense the rock is. My reasoning is this. My 150 gallon tank is equal to about 20 cubic feet of volume. So 7.5 gallons are equal to 1 cubic foot. If I get 6 rocks that are approx. 12"x12"x12", they would effectively displace 50 gallons of water, bringing my tank's capacity down to 100 gallons, requiring only 100 pounds of live rock rather than 150. Sort of circular logic, but I am just wondering what people base their live rock purchaases on.


Sorry if this makes no sense.

 

[Crazy8svt]

I don't think it's very porous but there tends to be a lot of caverns which is a good thing, a lot of places for things to hid. I understand your argument but if you ask a marine store how much rock to put in a 150 they'll tell you at least 150lbs. I bought 90lbs for my 90 gal. and when you buy corals it usually comes on a rock so I;m up to 110+ buy now. I wouldn't recommend putting it up stairs without some kind of support. It's also cooler downstairs so you might get away without a chiller, the lamps tend to make the water temp sore. good luck