Let's put a twist on this....and turn this into a fulll blown rock discussion.

Now I don't know an exact percentage but it's got to be quite high by now..but a lot of the LR we buy today has been farmed, someone leases big patch of ocean floor and dumps barges full of land rock down there and just lets it set until time to be harvested a few years later. Aside from the fact they are dealing with a lot more water... what would really be the difference between that and doing the same in a closed system? The rock I'm looking at is basically Lace Rock that has been setting in fresh water in a spillway for 50 years or so. I pruchased about 50 lbs of this type of rock, it's real origin is completely unknown, from an LFS to start the big tank here and seeded it with LR/LS and so far it's doing quite well with no apparent ill effects, granted it's only been wet for a few months now but rapidly coming full of life. It's very poruous and light weight, more like desert rock aka compressed sand, bit for $1.50ish a pound how can you go wrong. (BTW 50 pound filled three shopping bags and cost me less than a C note).