New tank question..

[SmallFry]

I don't know if this is the right forum to ask this, but it'll be a reef at some point... I have my new tank up and running - well sort of...

Most of the rock in there is DIY concrete rock. It seems to have finished curing and there I've got sand in there as well as salt water, all heated and the skimmer is ready to go. I've already got a few pounds of live rock in there from my other tank in there so there's been no die off or anything. I've also been dosing with sachem stability for a few days to help get things going.

I have a question, probably a bit of a stupid one buts here goes..

My question is, if I add a bit more rock from the other tank, then can I transfer a fish from the small tank. My logic is that if say, a third of the rock in the small tank can support one fish in a 27 gallon tank, then it is going to be able to support that same fish in the large tank/system of about 90 gallons total? I suppose what I'm asking is whether the bio load supported by a pound of rock is independent of the volume of water in the system or not?