Rock Talk

[Chago09]

Ok I have been having a debate on another forum and what someones outside opinion.

Live rock is so famous because of it being so porous which creates a lot of surface area for beneficial bacteria to grow and be your biological filtration and break down nitrates. So the rule is you must have 1lb per gallon in your tank. I wanted to set up a 150 gallon with 60 lbs of live rock in tank and another 30 in the sump. Aparently this can't be done for a FOWLR tank. your thoughts on that please??? Also I brought up the point of buying base rock or any rock that has no life on it but if very porous. Wouldn't that be the 100% exact same thing as buying the $10 per pound stuff??? I know the pet store bought stuff have living inverts and stuff already but I mean in terms of biological filtration wouldn't it be the exact same thing??? So buying 100lbs of base rock and 50 lbs of pre culture live rock, would be the exact same thing as buying 150lbs of live cultured rock????

[papagimp]

Base rock does not filter as well as regular live rock. Not as porous by far. Also, it's not just the porosity of the rock that makes live rock so good to use. Other rock may have minerals/elements in it that are harmful to your tank. Reef rocks do not, since they come from the reef. You could do a fowlr tank with that much rock, but you would need additional biological filtering. The rock isn't going to do enough.

Also, the rock in all likelyhood will not break down your nitrates. Just the ammonia and nitrites. You need an anerobic zone for the nitrates to be reduced. You can get this if you have enough liverock, the anerobic zones are going to be deep within the really porous rocks but not in large amounts. A DSB is anothe way to go for nitrate reduction.

Just a warning, it sounds like you are trying to go as cheaply as you can for this project without having to spend oodles on expensive live rock. I understand, but there is a reason reefers keep paying the high dollor for quality rock, it does make a difference. You can find ways to go cheaper, like buying up dry rock instead of cured live rock. and seed it yourself, but base rock is used more for aquascaping than anything. will not benefit your filtering capacity of the tank much.

[Village Idiot]

Join your local marine hobby club...someone on mine is selling some of their extra LR for $2.50/pound.

[Coffman34]

Yea, I thought about going the cheap route. But then I i got to look at the LR at my LFS, I thought, 9.99/lb, wow, that's alot, especially at 30-35 lbs. But it was soo beautiful, I bit the bullet, and bought it, and I'm glad I did.

Coffman34

[SeaView]

Well I have to say that completely diagree with papagimp. Good quality base rock or dry rock will perform 100% the same filtration as live rock minus the live organisms that are on it. Check out Marco rock or similar. You can also DIY your own rock and this will also filter 100% the same as live rock.

I suggest you do some more searches and read through the post. Don't take any one members opinion as the only way. Not even mine.

On a budget or in a FOWLR this sounds like a good choice for you.

Good Luck

[shag26272]

<a href=showthread.php?s=&postid=9558264#post9558264 target=_blank>Originally posted</a> by papagimp
Base rock does not filter as well as regular live rock. Not as porous by far. Also, it's not just the porosity of the rock that makes live rock so good to use. Other rock may have minerals/elements in it that are harmful to your tank. Reef rocks do not, since they come from the reef. You could do a fowlr tank with that much rock, but you would need additional biological filtering. The rock isn't going to do enough.

Also, the rock in all likelyhood will not break down your nitrates. Just the ammonia and nitrites. You need an anerobic zone for the nitrates to be reduced. You can get this if you have enough liverock, the anerobic zones are going to be deep within the really porous rocks but not in large amounts. A DSB is anothe way to go for nitrate reduction.

Just a warning, it sounds like you are trying to go as cheaply as you can for this project without having to spend oodles on expensive live rock. I understand, but there is a reason reefers keep paying the high dollor for quality rock, it does make a difference. You can find ways to go cheaper, like buying up dry rock instead of cured live rock. and seed it yourself, but base rock is used more for aquascaping than anything. will not benefit your filtering capacity of the tank much.

I disagree also, base rock is the same rock as Live rock , its just been out of the water and has dried out, it can be more porous or less porous then your live rock.

[oh_billy]

You know there are lots of web sites that you can get live rock for less than 10 bucks a pound. Check out liveaquaria.com. 4-5/lb shipped

[shag26272]

ebay has it for 2.15 a pound plus shipping, some prerty good looking stuff

[I am a giraffe]

Unless you're talking about pouring a glob of concrete and calling it "base rock," there's nothing wrong with using good base rock and then getting a chunk of live rock to seed it. I received my Marcorocks order the other day and the only difference between that stuff and the rock at the LFS is that it's dry and has nothing growing on it. If you're in a hurry to get your tank going, or feel that the hundred dollar bills are starting to weigh heavy in your pocket, then starting with all live rock would make sense, bu if you're trying to save money I'd suggest going the dead rock route.

[EdKruzel]

Don't get the term porous confused with the difference between actual reef rock and lava rock. Stuff like lava rock is very porous, but to the point that it traps detritius and becomes a nutrient sink.

I never bought into the crap of 1lb per gallon, rock has various weights by density and the "general" rule was made up by retailers to make money. I never add more than 50% by volume of the tank. Add enough to make a natural(s) reefscape your fish can claim as their territory. A DSB will provide denitrification, but is seldom proper for a fish only system because of the species kept (if they dig or feed from the sand, it won't work). In this case you can add minimal rock and a thin layer of sand (<2''). A thin layer of relatively fine grains will provide far more surface area for bacteria than 2lbs per gallon of rock. You can add a remote DSB through the use of a hang on refugium or within the sump. I'd forget the rubble in the sump as that is just another area to trap detritus.

[SaltyDr]

My guess is that there is confusion regarding "base" rock and dried out live rock. If you use dried out base rock (which many people call base rock) it will eventually perform just like live rock. It will take time to develop the beneficial bacteria, but in time (1-2 months) it will become "live". You must seed it with live rock, however. It too will become covered in coralline and eventually worms, pods, algae, etc will migrate to it and it will become indistinguishable from the live rock. Definitely a cheaper way to go but it does require extra patience.:)

[WaterKeeper]

:lol:

The debate shifted forums I see. A chunk of porous dead rock has the same biological filtering properties as a smooth chunk of marble. The reason LR is porous is that is formed by coral and other calcifying organisms bodies and that leads to a rock with a pitted surface. However, until bacteria colonize the inside spaces in those pores it has little, if any, filtering ability.

Bio-filtration is just what the name implies. A team effort by the living things on the rock to breakdown and detoxify waste. The main benefit of the pore structure is that they provide low oxygen areas where anaerobic bacteria can form and assist in converting nitrate to nitrogen gas.

Sure you can use mainly dead rock to start the tank and just seed it with some true LR. The drawback of course is that it takes a year or more for the seeded rock to reach the same filtering efficiency as good LR.

I don't really like placing part of the rock in the sump and the remainder in the tank. To me a sump is for circulation, to hide bulky equipment and to allow water changes. I like it clean and bare. There is also some thought that reducing the LR in the main tank much below a pound per gallon hampers its efficiency but that is part speculation and not entirely proven.

Now, back to the rock fights. ;)

[Chago09]

I wanna kiss you guys.... on this other site these guys were practically wanting my head on a platter because I said that I wanted to set up a 150 gallon with 80 lbs of live rock. Add maybe 20 or 30 lbs of base rock and there you go plenty of rock. They were all telling me I should have minimum 1.5lbs/gallon and that 1.5lbs is even better. These guys are nuts.... if this was the case how does a FO tank work???? these guys just get this info from there trusty pet store owner who tells them you need 1.5lbs/gallon and every protein skimmer less than $1000 is useless.