"Live Rock Per Gallon Rule" - Under, Over or Just Right?

BRS

Is this "Live Rock Per Gallon" rule relevant anymore?

  • YES

    Votes: 84 18.1%
  • NO

    Votes: 302 65.1%
  • Yes and No (please explain in the thread)

    Votes: 62 13.4%
  • Other (please explain)

    Votes: 16 3.4%

  • Total voters
    464

KingTideCorals

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So... theres two ways to look at this and I can attest for both sides of this since my tanks follow it both ways..

My Lagoon does not have the same amount of lbs of rock per gallon, but the added media helps with surface area for beneficial bacteria. I also have filter floss and other methods of filtration to help keep the tank clean..

Now.... My macroalgae project is minimal filtration so this rule was KEY, and actually I went above and beyond the amount of lbs for gallon. Pretty sure I have approx. 10-12 in a 4 Gallon tank!

Screen Shot 2021-03-20 at 2.41.45 AM.png
 

chaoticreefer

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To tell you the truth, my wall of rock (2 lb/gal) system from the early 2000s was a lot more stabler (when skimmers were in their infant stage) than my current system which had rock structure only enough to make it eye appealing. It took forever to figure it out, but the light went on in my head and I started to add some more rock in my DT, but a lot of it went into my sump along with Xport plate, the system has become much more stable. So I vote "yes and no", 1-2 lb is a good rule of thumb to give you an idea of a window. But...while it has to do with surface area (with blocks/plates like Xport, etc), it also has to do with inner rock where there's no/low oxygen. You would think you would see ammonia if you have too little rock, but that doesn't always hold true.
 

kutcha

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so it is a yes and no for me no because we have these new bio blocks that can hold 10x as much bacteria as our man made rock and the equipment we have has evolved, however it is a yes because even if your not going with 1lb per gallon you still need to have the surface area to maintain your bacteria to maintain a stable tank.
 

Belgian Anthias

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The carrying capacity of the system is partially dependable on the available surface. Adding aqua-scaping will increase the available surface. The more calcareous usable surface the less the alkalinity will be depleted by autotrophic bacterial activities. Must this be " live rock"? Live rock , hit, or myth? ref: MB Anthias 2018-2019
" live" rock and filtration capacity? A small piece of rock with marine " life" on and in it will be sufficient to seed all the rest. if the correct substrate is provided this only will take 3 to 4 weeks, from cycling the tank to conditioning the tank, a few weeks more to condition the tank to its full capacity., depending on how the tank is managed, active or passive, bio-filters are used or not. Diversity of micro-organisms is provided by introducing healthy animals and their holobionts, they will bring in all diversity needed for their survival, but also diseases and parasites, as does "real live rock".

There is no general rule available. The carrying capacity needed to support the bioload managing a VLNS or a HIHO system, a mixed reef, the difference is huge.
 

vlangel

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I voted yes and no. With the advances in tech and equipment it is certainly possible to keep a successful reef with the less than 2lbs of LR per gallon that I sold to customers at the LFS I worked for in 1997.
However that being said, in those days we never even heard of dinos. Cyano only happened to our clients who were grossly overfeeding.
Surface area for beneficial bio-life can be replicated as can export of nutrients. Diversity of bio-life however can not and that is an aspect of reef keeping that is overlooked today. Back in the day we reefers used to trade a cup of sand with each other to promote even more bio-life in our tanks.
I have kept my LR that I bought in the late 90s and early 2000s and am still using it today. I have never had dinos. My tank has a lot of LR but is not the dreaded rock wall because a lot of it is under the sandbed to help promote denitrification, (another under-rated concept). My tank is heavily fed, has a lot of fish and the filtration is totally the bio filter consisting of LR, DSB and a fuge with macro algae. It has no skimmer, no reactors, no bio media. Occasionally I add carbon to remove tannins but that is it. By design I run NO3 and PO4 high for the macro algaes to flourish. I happily do this as it allows me to have as many fish as I can have in my display as long as they all get along. The LR gives them territories and I think my DT has an appealing, natural look to it.
That being said, what I do would not work for a primarily acro tank so it is not a method for everyone. I however love the stability and ease of maintenance.
 

Timfish

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Assuming we're talking about wild or maricultured live rock, never was. When Delbeek and Sprung discussed live rock in their "Reef Aquarium" series of books they point out only a few pounds is needed to add the diversity to a system. In my own experience over the decades I've been setting up systems I've been very happy with the results using only 1/3 to 1/2 lb per gallon.

On the other hand, since wild and maricultured live rock has cryptic sponges which remove labile DOC and most importantly the hydrophilic forms of dissolved combined neutral sugars detrimental to corals getting so called live rock that only has cultured bacteria is a waste of money IMO.
 

Subsea

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I voted yes and no. With the advances in tech and equipment it is certainly possible to keep a successful reef with the less than 2lbs of LR per gallon that I sold to customers at the LFS I worked for in 1997.
However that being said, in those days we never even heard of dinos. Cyano only happened to our clients who were grossly overfeeding.
Surface area for beneficial bio-life can be replicated as can export of nutrients. Diversity of bio-life however can not and that is an aspect of reef keeping that is overlooked today. Back in the day we reefers used to trade a cup of sand with each other to promote even more bio-life in our tanks.
I have kept my LR that I bought in the late 90s and early 2000s and am still using it today. I have never had dinos. My tank has a lot of LR but is not the dreaded rock wall because a lot of it is under the sandbed to help promote denitrification, (another under-rated concept). My tank is heavily fed, has a lot of fish and the filtration is totally the bio filter consisting of LR, DSB and a fuge with macro algae. It has no skimmer, no reactors, no bio media. Occasionally I add carbon to remove tannins but that is it. By design I run NO3 and PO4 high for the macro algaes to flourish. I happily do this as it allows me to have as many fish as I can have in my display as long as they all get along. The LR gives them territories and I think my DT has an appealing, natural look to it.
That being said, what I do would not work for a primarily acro tank so it is not a method for everyone. I however love the stability and ease of maintenance.

Dawn,

kudos to your system. I like the diversity of ornamental and utility macro you have used to stabilize your system.

I use substrate in my display tank as my biofilter that processes organic & inorganic nutrients into multiple live food webs that feed hungry mouths. The live rock provides structure in the tank for fish and invert placement.

I use uncured, diver collected live rock from the GOM to bring in diversity of micro & macro fana and fauna. I like open spaces to observe fish interaction. With a high nutrient tank, I favor invertebrate like fans, feathers and bivalves.
 
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Treefer32

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I said no, it's not relevent just as the typewriter is no longer relevent to people. Are there aspects of the typewriter still around? Yes, definitely, we have keyboards that echo the layout of letters on the good old typewriter. And we have the option to print to paper if we want. That's about all that's the same, but there's aspects still relevent. As many others before me have said, there's technological advances in biofiltration. We understand the needs of our marine environments better than ever. We have "hobby grade" test kits that are probably more accurate than they ever have been to tell us if filtration isn't working.

Advances in bacterial strains, efficient export mechanisms (advanced skimmers, advanced algae turf scrubbers) and even advances in sump designs, roller mats, etc all contribute to how much rock a person needs.

I would say if anything we need an equation that calculates x amount of lbs of rock. And the variables that determine it include:
1.) Size of tank
2.) size of sump.
3.) Roller mat yes/ no?
4.) Socks yes / no?
5.) Skimmer yes / no
6. If yes to skimmer rating of skimmer.
7. algae turf scrubber yes / no?
8. If yes to ATS - some size rating of the ats.
9. Refugium yes / no?
10. Number of fish planned?
11. other factors yes / no.

Then, based some convuluted equation, you can say, you should have x lbs of rock. Now, that said, Go with what looks nice for creating the habitat you want (plenty of hiding places.

Any pics of multiple sumps used. Like a live rock sump or a sump dedicated to a couple brightwell bricks and then a sump dedicated to equipment all linked together?
 

schuby

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Most everyone seems fixated on the filtering, surface-area-for-bacteria benefits of the amount of rock we put in our reef DTs. Another tremendous benefit, mostly ignored or mostly unknown, is that rock can provide hiding-places for our fish. How many threads are there on this site with people having fish-aggression issues? To me, it seems that these folks usually have a DT with minimal rock and perform minimal feeding.

In my limited experience with two tanks (90 gal for 11 years and 150 gal for 2 years now), a large amount of porous rock in the DT and feeding-what-fish-will-eat-in-5-minutes plus nori-for-a-day results in very little fish-aggression. Hungry fish get "hangry" easily. We can't feed them Snickers, but we can feed them adequately and provide some personal-space (out of sight, out of mind). I'll probably never have a massive, 300+ gallon tank, but I can add more rock to my tank for my fish's mental-health.
 

ReefGeezer

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Where a system relies solely on this substrate, more is required. Where organisms are using most of the ammonia produced directly, or where other means of exporting or binding nitrogen compounds are used, less is required. The substrate doesn't need to be live rock. Porous dry rock, new fangled bio-blocks, sand, and a host of other substrates can do the job. But live rock brings more to the party.

FWIW, My new 90 was set up with ~50 lbs. of dry rock (because I like height on my aquascape), less than a couple inches of sand, about 15 lbs. of live rock, and 5 lbs. of Garf Grunge. I expect that it will maintain nitrogen compounds at acceptable levels until such time as the corals and other organisms start to use up the nitrogen compounds directly as the system matures.
 

Bruce Burnett

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Most everyone seems fixated on the filtering, surface-area-for-bacteria benefits of the amount of rock we put in our reef DTs. Another tremendous benefit, mostly ignored or mostly unknown, is that rock can provide hiding-places for our fish. How many threads are there on this site with people having fish-aggression issues? To me, it seems that these folks usually have a DT with minimal rock and perform minimal feeding.

In my limited experience with two tanks (90 gal for 11 years and 150 gal for 2 years now), a large amount of porous rock in the DT and feeding-what-fish-will-eat-in-5-minutes plus nori-for-a-day results in very little fish-aggression. Hungry fish get "hangry" easily. We can't feed them Snickers, but we can feed them adequately and provide some personal-space (out of sight, out of mind). I'll probably never have a massive, 300+ gallon tank, but I can add more rock to my tank for my fish's mental-health.
My sentiments but I have had a 300 gallon display. Going smaller to much time and expense for the bigger displays. Use to think I wanted 500- 1000 gallon display now I am going to be happy with a 65 gallon display smallest saltwater tank I will have owned
 

StPatrick89

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As a beginner who just put DRY ROCK in my tank a week and a half ago, I tried following this 1G rule and I have too much rock left over. Thankfully my LFS is willing to exchange for credit. I have peaks and valleys in my tank and still have too much. I have a 75G tank. Probably only needed 45-50lbs. Honestky
 

Anchor

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I look at frag tanks and see nothing but plastic racks, a skimmer and filter socks being successful.. Where does pounds of rock fall in this scenario? Rock can be irrelevant.. Now, using something as a fallback may not be a bad idea.. whether rock or manufactured cubes in the sump can be helpful in times of trouble. Keep in mind, bacteria doesnt just occupy rocks, it can occupy any surface. And lastly, the size and amount of ammonia producing inhabitants has a lot to do with the amount of surface you might need.
 
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BRS

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