I post this a lot in different threads on different boards, so I am going lay my thoughts out to not derail other threads anymore. If you don't agree with my views, then cool.
Live rock is super important to the tank. It will lower nitrate and bond phosphate that later allows bacteria to swap the P off of the rock when it needs it to grow. When you buy live rock from the ocean, that live rock has bacteria and micro fauna all the way in the center that established over many years, is typically phosphate free and is ready for action. There is no substitute for this IMO.
Where you get the rock matters. Nice rock from the pacific is very light and will allow more bacteria and micro fauna to live in the rock. It typically costs more, but since it is lighter, it will take up more space for less money. The worst rock around IMO is the stuff mined out of quarries and left in the Atlantic for a few months to get some stuff on the outside - very little can live on the interior of this since it is so dense and most of the stuff on the outside dies anyway. A basketball sized rock from Marshall Island might weigh 6-8 pounds, so even at $9 a pound, that is cheaper than a 30 pound Atlantic rock the same size at $5 a pound.
Rock that looks good on the outside might not be doing it's job on the inside. Live rock is more than having coralline on it.
Dry rock used to have all of that micro fauna and bacteria, but now it is dead. It can take years for both the dead fauna and bacteria to fully leave the rock and then to repopulate to the center with beneficial organisms. Also, the decay from inside of the rock will pollute your tank and add excess N and P to the system - most of the P can get absorbed by calcium carbonate, but this will allow less absorption as your tank ages. Don't believe me? Break a piece of dry rock in half after a year and you can see where the new population starts and the old dead stuff is still in there. You can also dissolve some of the exterior parts of the rock in carbonated water or with acid and test for phosphate... it will likely be high.
Man Made Rock needs to populated with bacteria. Most companies do this for a few months before selling. The exterior of the rock has some bacteria and micro fauna on it. It is very dense. If you break a piece of it in half after a year, it is hard to see much bacteria and micro fauna... it looks like dense quarried rock. It is not as good of a filter IMO than more porous live rock. It should be phosphate free unlike dry rock.
Most people like man-made or dry rock because it has no pests. All that it takes is one frag plug to load your tank up with bryopsis, bubble algae, aiptasia and all other kinds of nastiness. If you appropriately cure ocean live rock the only really issues that come up regularly is the occasional mantis shrimp from Atlantic rock... and I guess even a Sunburst Anenome as a hitchhiker. Once you add your first coral, your sterile rock is gone and you better have a plan like everybody else to keep the nastiness at bay.
If your rock is nasty with algae and other pests, IMO you are better off cooking it in water for 3-6 months rather than acid bath or bleach it. It is not fast in the short term, but in the long term, the cooked rock will be pest free, phosphate free and ready for service as a filter. Good, porous, live rock will help keep your algae down since it works so well to combat nitrate and bind/swap P with bacteria taking it out of the water column until needed for growth.
Personally, I would use real live rock as the majority of rock in the system and limit the use of non-live-rock to special structures and arches and stuff where you really need it for cool shapes and stuff.
YMMV, but there is mine...
Live rock is super important to the tank. It will lower nitrate and bond phosphate that later allows bacteria to swap the P off of the rock when it needs it to grow. When you buy live rock from the ocean, that live rock has bacteria and micro fauna all the way in the center that established over many years, is typically phosphate free and is ready for action. There is no substitute for this IMO.
Where you get the rock matters. Nice rock from the pacific is very light and will allow more bacteria and micro fauna to live in the rock. It typically costs more, but since it is lighter, it will take up more space for less money. The worst rock around IMO is the stuff mined out of quarries and left in the Atlantic for a few months to get some stuff on the outside - very little can live on the interior of this since it is so dense and most of the stuff on the outside dies anyway. A basketball sized rock from Marshall Island might weigh 6-8 pounds, so even at $9 a pound, that is cheaper than a 30 pound Atlantic rock the same size at $5 a pound.
Rock that looks good on the outside might not be doing it's job on the inside. Live rock is more than having coralline on it.
Dry rock used to have all of that micro fauna and bacteria, but now it is dead. It can take years for both the dead fauna and bacteria to fully leave the rock and then to repopulate to the center with beneficial organisms. Also, the decay from inside of the rock will pollute your tank and add excess N and P to the system - most of the P can get absorbed by calcium carbonate, but this will allow less absorption as your tank ages. Don't believe me? Break a piece of dry rock in half after a year and you can see where the new population starts and the old dead stuff is still in there. You can also dissolve some of the exterior parts of the rock in carbonated water or with acid and test for phosphate... it will likely be high.
Man Made Rock needs to populated with bacteria. Most companies do this for a few months before selling. The exterior of the rock has some bacteria and micro fauna on it. It is very dense. If you break a piece of it in half after a year, it is hard to see much bacteria and micro fauna... it looks like dense quarried rock. It is not as good of a filter IMO than more porous live rock. It should be phosphate free unlike dry rock.
Most people like man-made or dry rock because it has no pests. All that it takes is one frag plug to load your tank up with bryopsis, bubble algae, aiptasia and all other kinds of nastiness. If you appropriately cure ocean live rock the only really issues that come up regularly is the occasional mantis shrimp from Atlantic rock... and I guess even a Sunburst Anenome as a hitchhiker. Once you add your first coral, your sterile rock is gone and you better have a plan like everybody else to keep the nastiness at bay.
If your rock is nasty with algae and other pests, IMO you are better off cooking it in water for 3-6 months rather than acid bath or bleach it. It is not fast in the short term, but in the long term, the cooked rock will be pest free, phosphate free and ready for service as a filter. Good, porous, live rock will help keep your algae down since it works so well to combat nitrate and bind/swap P with bacteria taking it out of the water column until needed for growth.
Personally, I would use real live rock as the majority of rock in the system and limit the use of non-live-rock to special structures and arches and stuff where you really need it for cool shapes and stuff.
YMMV, but there is mine...
