Liverock Stocking levels

[mps9506]

So over the last ten years or so I've heard all kinds of rules of thumb for how much live rock you need in a reef tank.
My question is; How do you know how much live rock you REALLY need?

The old rule of thumb for the classic Fiji Live rock was anywhere from 1-2lb's/gallon. Then later on I've heard as much as 3-4 per gallon. Then for lighter rock like Vanuatu I've heard go less. And for heavier aquacultured rock you need to go more.

I think we need to remember this is a rule of thumb, or maybe a starting point to get an idea for how much live rock you might need. You might need less, you might need more.
For instance if you have a tank with a light fish load, and keep a high concentration of live SPS coral the bioload in your tank is significantly less. Therefore less liverock is required to provide a substrate for bacteria to do their job. If you want to keep a heavier stock of fish, than more liverock will be necessary to help keep enough bacteria alive to process that nitrogen.

Just some food for thought.
Flame away if you want

 

[Dentoid]

Nicely said Mike!

 

[sasquatch]

How much do you really Need, makes me think can there ever be enough? Display space is the limiting factor, the addition of LR storage has to be a factor in the long view of a reef, I cant really see just a tank with the basics stuffed into it being very healthy after 1 or 2 years?

 

[mps9506]

All I can say is that previously I have maintained a healthy SPS reef tank on less than one pound per gallon of Fiji live rock for about a year and a half before I moved. I know that is not a long time by any means (I had a DSB system go bad in a tank in about the same amount of time).
AFA as basics it had live rock, skimmer, halides, no substrate, two fish and lots of corals and lots of flow. Ca, alk, pH were rock steady. Ammonia , nitrites and nitrates were not a factor.
Those are the basics. I will admit it did not look as nice as a tank stuffed with corals and fish, but I was more interested in growing corals to frag and trade.

 

[sasquatch]

Is there no other benefit than denitrification after the initial seeding etc at curing time?

 

[Dentoid]

Is there no other benefit than denitrification after the initial seeding etc at curing time?

From Calfo & Fenner's book, Reef Invertebrates-An Essential guide to Selection, Care and Compatibility here are some benefits of LR:

Nutrient Cycling
Food Production
Nutrient Limitation
Behavioral Enrichment
Seeding Non-living Substrates
Mediating Water Quality
Aesthetics

 

[AdvanceAquatics]

Wow great Thought... i always went on visual effect and if anything live rock in the Sump/Ref to keep balanced. I wounder though If you place in the heavier rocks vers the lighter rocks, how dose that really effect the water due to displacement. If you had a 50g and you fallowed the rule of 3lbs( just example)per gal. Your at 150lbs of rock. Now even the Fiji mass is still at least 40% ( just example) which would mean any were between X amount of gal of water is lost due to mass displacement. Thus making a 50g really a (50-X=Y) Y amount tank. Meaning you actually over stocked your tank with rock vers the rule. No matter what it is. I agree its great to have an ideal of were to start, and I agree with over Bio filtration as much as one can before the eco gose out of control and back firers (LOL) but It really should fallow Gal.v Coral ( if reef > then Fish).v Fish (inch of Fish total).v Rock. simply because the filtraton will reflect the Reef>Fish or the Reef<Fish and so will the rock.

Very complex so in short:
if you had a 50g and you stocked < Fish=20"total you rock level would incorpate that such as (just example) 90-115lbs + a Higher Focus on Bio-Filtration.
Were it was <Reef=10"total your rock level would be greater 120-150lbs= filtration focuses on reef needs vers Fish needs.

I could be wronge in my thought but my rule would be more fish more water in tank stronger Bio filter, such as Sump/Ref. More Coral more rock and you could do with just Sump.

Im interested in others thoughts considering I never realy mentaly dug this deep of that topic LOL

 

[mps9506]

Wow great Thought... i always went on visual effect and if anything live rock in the Sump/Ref to keep balanced. I wounder though If you place in the heavier rocks vers the lighter rocks, how dose that really effect the water due to displacement. If you had a 50g and you fallowed the rule of 3lbs( just example)per gal. Your at 150lbs of rock. Now even the Fiji mass is still at least 40% ( just example) which would mean any were between X amount of gal of water is lost due to mass displacement. Thus making a 50g really a (50-X=Y) Y amount tank. Meaning you actually over stocked your tank with rock vers the rule. No matter what it is. I agree its great to have an ideal of were to start, and I agree with over Bio filtration as much as one can before the eco gose out of control and back firers (LOL) but It really should fallow Gal.v Coral ( if reef > then Fish).v Fish (inch of Fish total).v Rock. simply because the filtraton will reflect the Reef>Fish or the Reef<Fish and so will the rock.

Very complex so in short:
if you had a 50g and you stocked < Fish=20"total you rock level would incorpate that such as (just example) 90-115lbs + a Higher Focus on Bio-Filtration.
Were it was <Reef=10"total your rock level would be greater 120-150lbs= filtration focuses on reef needs vers Fish needs.

I could be wronge in my thought but my rule would be more fish more water in tank stronger Bio filter, such as Sump/Ref. More Coral more rock and you could do with just Sump.

Im interested in others thoughts considering I never realy mentaly dug this deep of that topic LOL

I'd reply but I need sleep because I read it and it passed right through my head. I'll read it again in the morning

 

[prow]

cool thread mike. something i think most never really think about. good topic for sure.

for the lbs/gal rule thing i dont go by that at all. i use it more like the 2" or 1", whatever it is, fish rule. just too many variables. like the fact some corals up take mass nutrients thus the rock has less to deal with, other corals not so much. just like fish anthias, tangs whatever have very different habbits and effects on the tank and its filtration, not just their waste but what they eat aswell. then there is the sulfer cycle which alone, with a holistic view, makes it almost impossible to evaluate LR's nitrogen cycle. but we do need a starting point, lbs/gal for rock type might be something more useful. geussing here maybe something like 0.5-1lb/gal for low density, 1-1.5lbs for med density and 1.5-2+lbs for dense rock.

for aquacultured rock i do think you need more lbs to get the same surface area. simply because collected rock has had years, no decades, no centuries, well you know, for creatures/bac/ect..to make a home in. aquacultured just has not had as many things clear spots, which increases the surface area, to call home yet. even denses collected, i would think, would have a greater surface area of a given mass.

 

[DrHank]

Let me throw another monkey wrench into the equation. Mass is not equal to weight. How much mass (or volume) a 1 lb piece of rock occupies is highly variable. We all know this. But how much bio activity does it impart and what type is another issue. The more porous the rock is the more room there is for "aerobic" bacteria there is. The denser the rock is the more area there is for "anaerobic" bacteria colonization there is.

To me, this is why the 1 1-2 to 2 lb per gallon rule still applies. I think that to have a truly effective ammonia cycle (ammonia to nitrogen gas) you need a mixture of types of rock. Some of us (not me) use a DSB to convert nitrate to nitrogen gas. My real concern is that another by product of anaerobic bacterial activity is the production of hydrogen sulfide gas. If the DSB becomes disturbed and this is released in the tank, you will likely have a very rapid and often massive crash. Hydrogen sulfide gas is also produced in very dense rock however, it is released at a much slower rate in extremely small amounts which can and are rapidly and safely eliminate.

Well, that's my two cents worth. Just some other considerations and the reason that I prefer a SSB and a mixture of different types of rock. You can also remove nitrate effectively through macroalgae export (which is the way I do it).

May confusion reign!

 

[Cougra]

I've been personally questioning the amount of rock that seems to be recommended for a while now. It seems these figures seem to be climbing higher and higher with the "more is better" mentality but with seemingly little thought as to what this means for the tank in general. The more rock you place in the tank the less water you have in there. At some point there is a trade-off between the benefits of the extra rock and the amount of water displaced and even the overall visual effect of the tank. I find that we are becoming limited in how we can aquascape the tank due to the vast amount of rock everyone tells us we need. Sure we can move some of it to a sump or refugium but those of us with very limited space can't always have multiple tanks just to house the rock so they go in the display tank.

As to the recommended weights, when I started my reef we basically only had Fiji Live rock available and the recommendations at the time was between 1-1.5lb/gal (US). I have had my tank running for over 7 years with around that amount of rock and have never had a problem with high ammonia, nitrites, or nitrates and I have had the tank fairly heavily stocked on occasion. Personally I can't see how having a lot more rock can give any additional benefit if the lesser amount already does the job.

Wouldn't adding too much live rock result in not enough food for the beneficial organisms to live on and thus reducing the overall efficiency of the rock itself?

 

[DrHank]

I have had my tank running for over 7 years ... and have never had a problem with high ammonia, nitrites, or nitrates and I have had the tank fairly heavily stocked on occasion.

You hit the nail right on the head! That is exactly what it is all about. In this hobby, nothing is absolute. You have to learn for yourself what works best. Everything is just a guideline and methods change over time. Who knows if 20 years from now someone invents a whatcha-ma-call-it that out performs the protein skimmer. Everyone will want to scrap their skimmers and go for what works better.

What really matters is that your livestock has done well in your tank for over seven years and you are (and should be) happy about it.

 

[prow]

dont you just love life. with all the advances in skimmers, phos media, the increased use of macros and refugiums among other things, the lbs/gal rule has never changed. perhaps its time for a update on that huh.

one thing i can think of is that most rock will provide the tank with a buffer system. not the most effective but over time will help keep things on a even keel. mabe a mute point considering the various buffers we now know about. but some dont know the difference between type of buffer out there. more rock would aid the tank in these cases.

 

[mps9506]

Let me throw another monkey wrench into the equation. Mass is not equal to weight. How much mass (or volume) a 1 lb piece of rock occupies is highly variable. We all know this. But how much bio activity does it impart and what type is another issue. The more porous the rock is the more room there is for "aerobic" bacteria there is. The denser the rock is the more area there is for "anaerobic" bacteria colonization there is.

This does make sense to some extent, but what I really wonder I guess is how much live rock do we need for a sufcient amount of anaerobic bacteria to grow? I know there isn't an answer for this since there are lots of variables. But I think that was really what I'm trying to lead to. How much bacterial filtration is necessary for a reef tank with x amount of biomass in it?

Again no single rigt answer here, but something to chew on.

 

[prow]

i know were your going with this. i would have to say enough average rock to add up to about double the fishes body mass should be good. i have keep a fish in QT before for around 5 months with minimal water changes. the only other thing i had was some caulerpa growing on the rock, so i dont know if that counts but still i go with double the mass of rock to fish. not looking at lbs here just mass.

 

[mps9506]

i know were your going with this. i would have to say enough average rock to add up to about double the fishes body mass should be good. i have keep a fish in QT before for around 5 months with minimal water changes. the only other thing i had was some caulerpa growing on the rock, so i dont know if that counts but still i go with double the mass of rock to fish. not looking at lbs here just mass.

Well, fish are easy. what about corals?

 

[cheeks69]

I never liked this rule and never really followed it. I think there's alot of negatives by keeping a large amount of rock in the tank like poor flow, detritus accumulation within the rocks, lack of swimming space etc.

I have about 65 lbs. of LR in my 93 gal tank and 15 lbs. in my 21 gallon sump and still think it's too much especially as the SPS corals continue to grow. I do have a DSB so I have plenty of surface area for aerobic/anaerobic bacteria. This of course will be different if you have a SSB or BB tank, you'd need considerably more rock but nowhere near the amount usually recomended especially if it's the porous Indo-Pacific rock.

 

[AdvanceAquatics]

LOL...Interesting and everone had a great point, but allow me to further the thought yet deeper. The thought is complex due to the amount of Gals and what you actually are keeping. The Doc is right with the Rock differances, so that makes it more complex. But Yet in life the answer is almost always very simple we just asume its complex and over look the simple.

I really agree with Doc...it all depends on you your aquatic life and the enviorment you creat for them.

 

[mps9506]

So do you think the more porous varieties of rock contain more or less anaerobic bacteria, or which is more effective at denitrification.

 

[prow]

one more big wrench to toss in. there are marine bacteria that have been found that are capable of both anaerobic and aerobic resp. not only that but they are able to perform anaerobic respriations in a aerobic environment. meaning it does both nitrification and denitrification. even at the same time:invisible

corals not so dependant on rock. more of what is in the water column.