Live rock rule

[RV Reefs]

I have a 20 gallon aquarium with a 5 gallon sump. While at my LFS, they said that i should have 1 pound of live rock per gallon. This seems like it would lead to not enough swim space. What do you think?

 

[Mywifeisgunnakillme]

You could no live rock or a lot. Some corals will have all the bacteria you need. Live rock, if real live rock, can help mature a tank more quickly. Personally i'd just use as much as looks good to you. I would not put it higher than 1/3 or a 1/2 up the tank so corals can grow and fish can swim.

 

[Max H.]

You could put as much as you want. I have 50 pounds of rock on my 32 gallon.

 

[aggrofish]

throw some biomedia in the sump and use as little or as much rock as you’d like

 

[Azedenkae]

I have a 20 gallon aquarium with a 5 gallon sump. While at my LFS, they said that i should have 1 pound of live rock per gallon. This seems like it would lead to not enough swim space. What do you think?

Yeah it can take up a bit of space. You can use less, then supplement with really good biomedia like MarinePure in your sump instead. That works too.

 

[Mywifeisgunnakillme]

My ten gallon qt coral tank has no rock or sand.... so its really whatever looks good. Bacteria will grow plenty wherever.

If you have high fishload, some people think rock or bio media can help reduce nitrate accumulation. Maybe, no hard proof there; i havent really seen a lot of (or any) posts where someone had 50ppm nitrate added bio media and had 5ppm...

Other methods reduce nitrate more reliably.

The tank itself will support plenty of bacteria to cycle for fish, nitrogen cycle.

 

[RV Reefs]

Thanks everyone. I wanted to trust my gut and not put that much rock in the tank but I wanted to be sure.

 

[waterbox15aio]

1lb per gallon is a general rule. Not all of the rock needs to be live 25 live:75 dry is fine to save costs. If you go with predominately dry rock, you may want to use a bacteria starter like biospira.

A modern branch style scape may have 0.5lbs per gallon or less while a rock wall could have 2+lbs per gallon. Depends on what you want. Different rocks types also have different densities so lower density more porous rocks require less weight to fill the same volume as a denser rock.

I’d also suggest getting some dryrock to supplement live. I generally buy about 10% more dryrock then needed to give me more options when scaping with the unused dry rocks generally broken up for frags.

 

[dutch27]

I feel like the 1 lb/gal rule is from a time when people mostly used harvested rock that shipped wet. If using dry rock I'd go significantly less. Order 15 lbs so you have options on how to get the scape together, throw the rest in the sump.

 

[Mywifeisgunnakillme]

I feel like the 1 lb/gal rule is from a time when people mostly used harvested rock that shipped wet. If using dry rock I'd go significantly less. Order 15 lbs so you have options on how to get the scape together, throw the rest in the sump.

Or the 1lb pound a gallon rule was to make a lot of money..... I certainly spent thousands on rock then.... Still have some of it...

Now the industry makes a lot of money lights, lol, and pushes that...

 

[o2manyfish]

You have to remember what the live rock does... Its surface area for filtration. If you are running a small tank with a couple of fish then you really don't need to filter that much waste. But if you like fish and you want a tank packed with movement and color then you need to have the filtration available to maintain that amount of waste without affecting water quality, and that's where having more live rock gives you that ability. I've average 1.5 to 2lbs per gallon for the past 20 years and have never worried about having too many fish in my tank. I like smaller fish - so no Vlamingis, but I've kept 20+ tangs with another 130 fish in a 400g tank and never had and filtration issues. And also didn't have to do water changes. But my system is bigger than most. But the rules surface area for biological filtration remains the same. ---- The caveat to this is Coraline algae. Everyone wants that purple rock. But what happens to your surface area when you take a porous rock with lots of biological surface area and cover it in a solid coraline algae... Having seem mature coraline get over 1/4" thick and literally suffocate a rock I'm of the mindset that the purple coraline is more of a detriment to the long term health of your rock and your tank - than it is a benefit for 'Lookin Cool'.

Dave B

 

[tharbin]

There are lots of axioms in the hobby. The one pound per gallon idea is a good starting point to get into the hobby. That axiom was already old news when I started in 1976, It works, but it is not the only way to go. If you start with a bare tank, no filtration of any sort, no rock, no sand, no bio-media or mechanical filtration, the only surface area available for the necessary beneficial is the tank glass. Not only is that a relatively small area it is also a poor area for bacterial loading. The goal is to have enough surface area in the tank/sump/rear chambers to house enough bacteria to properly de-nitrate the tank.

There are of course other goals. Here is the first one: what do want to provide homes for in your tank. Just corals, corals and fish, just fish, a natural reef, what kind lagoon/deep water/reef crest/etc.? The point I'm trying to make is what you want to house plays a part in your aquascaping decisions.

So does your available time to "tinker" with the tank and your feelings about technology versus nature. Just about anything that can be accomplished with technology can also be accomplished with nature instead. It depends on what you like and what you can/want to afford.

You need a place for bacterial filtration. Rock and sand are the traditional choices but various bio-media can fulfill the need in less space. You can also rely mainly on water changes. If you want nothing but photosynthetic corals, no fish or inverts you can get by with no rock but it won't be a reef it will be a coral farm. I've never seen it in print but my feeling is that you can pretty much count the weight of your corals as part of the pounds/gallon idea. They do provide surface area for bacteria and also filter the water.

The rock is a major portion of the surface area. So how much do you need? It depends to a large extent on your fish load. They are the main producer of Ammonia which is the largest concern as even small amounts are toxic to fish. The more fish you plan to keep per gallon the more rock/bio-media per gallon you should provide. Today the emphasis has shifted to less fish per gallon and more corals per gallon. I think that somewhere around a third to a half a pound per gallon is probably a good starting point.

Edit--- I should have added, I personally use about one pound per gallon and it is my main filtration for the tank. Low tech is my preference. I also prefer to provide hiding places and view blocks for my fish to reduce stress and aggression.

 

[WVNed]

I would go with 1 pound per gallon. That is what I have always done. It has always worked well.
I have 400 pounds in 400 gallons now.

You said swim space. Most small fish are not comfortable without structure to swim around and hide in.