Live Rock Mass vs. Weight

[krisfal]

I am in the process of setting up a 130g. I currently have aprox 120 lbs of live rock in it. The rock is pretty light weight compared to its mass. So I began to wonder about the general rule of 1 to 1.5 lbs per gallon. I did some searching through some old threads and found a few opinions that indicated the mass of rock was more critical than the weight. However, when it came to estimating the volumes needed, there were only 2 guidelines that I could find, one indicating 1/2 - 2/3 of the tank volume and the other indicating 1/4-1/3 of the tank volume.

So what are your opinions on the volume of LR?

I am planning on having a few tangs and am trying to leave plenty of swimming room, but at the same time I do not want to skimp on the biological filtration of the live rock.

 

[matts125]

If this is the rock from Toms tank then I would say it is plenty of rock for a 130, it is very light weight rock.

Besides you dont want to be like me and cram over 300lbs in a 125 gallon tank do you??

Matt

 

[Scooterman]

There is no opinion when it come to rocks that are more porous will house more bacteria so you won't need as much, regardless of the weight. Now how much do you need yea that varies from tank to tank, I plan on building supports to cover the bottom & allow flow throughout the entire rock structure & will use less rocks but that part is more of a personal choice. With good skimming, & other means of filtrations & light bio-loads you can get away with less rock!

 

[Krish]

I agree totally with Scooty. Weight isn't what it's all about, but I guess they say 1-2lbs per gal to give people something to go on, but porous is best Good luck!

 

[big t]

You have more then enough rock to run a 200+ gallon system. That is about all the rock that I had total for 300+ and it worked fine for me.

 

[Meche]

FYI, in case this thread gets more technical lets be clear about what your talking about. Mass * Gravity = Weight. Because gravity does not change on earth you may use them interchangeably, just be careful of the units.

I think you mean to differentiate between weight and density. Density is how much it weighs vs its volume. density= weight/ volume.

 

[Herefishyfishy]

Some rock from the Caribbean is solid boulders and some south pacific rock is so porous that it almost floats. I assume the suggested ratio should not be weight of rock to gallons of water, but to volume of rock in ratio to volume of water including sump. The displacement volume of rock would be the only semi-accurate measure.

 

[dnjan]

FYI, in case this thread gets more technical lets be clear about what your talking about. Mass * Gravity = Weight. Because gravity does not change on earth you may use them interchangeably, just be careful of the units.

I think you mean to differentiate between weight and density. Density is how much it weighs vs its volume. density= weight/ volume.

Thankyou Thankyou Thankyou! I have been wanting to correct that mass or weight thing for days, but just didn't want to be the bulletinboard nerd. Glad you had the courage!

 

[krisfal]

I was hesitant to use the word "mass" so I looked it up in the dictionary prior to posting. Although in physics the definition of mass is "the quantity of matter as determined from its weight" the dictionary also list this definition "bulk, size, expanse, or massiveness" so I felt it was a proper use :shock: By reading over the replies it appears most understood what I was getting at. Thanks for all the replies, especially, matts125 and big t since you both know the exact rock I am talking about.

I think I will give it a go with the rock I have and see how it works out.

 

[Scooterman]

I think people are confusing Mass with density big difference! I like a rock with large mass & porous or less dense than others! Is that easier to understand LOL!

 

[MikeS]

Well, for the average reefkeeper, Mass can be interpreted as "weight"...The more massive an object is, the more it weighs basically. Volume is how "large" it is, which has nothing to to with how much it weighs. Density is the ratio between the two values...a rock that weighs more with the same volume as another rock is more dense. Porous is different as well, it's a measurement of permeabiltiy,....a less dense rock may not necessarily be more porous, it could have to do with the mineral makeup of the rock. But generally speaking when it comes to live rock, density and porousity will tend to correlate....

The Lbs/gallon rule for LR is #1, totally vauge and reletive to a great deal of factors, and #2, as far as I know an imaginary number dreamed up by somebody somewhere way back in reefkeeping and heas been passed along from one hobbyist to the next until it became a "standard"....I have yet to see one single study or anything even close of that nature that actually suggests that there is a minimum amount of LR necessary for a reef tank.

My suggestion would be to get the amount of LR in the shapes and sizes you need to aquascape the tank the way you would like it....the less dense the LR, the better for biological purposes....

Thankyou Thankyou Thankyou! I have been wanting to correct that mass or weight thing for days, but just didn't want to be the bulletinboard nerd. Glad you had the courage!

No worries...I don't think anybody will ever de-throne Nikki for the title of bulletinboard NERD....:lol:

MikeS

 

[KRMNAL1]

Well, for the average reefkeeper, Mass can be interpreted as "weight"...The more massive an object is, the more it weighs basically. Volume is how "large" it is, which has nothing to to with how much it weighs. Density is the ratio between the two values...a rock that weighs more with the same volume as another rock is more dense. Porous is different as well, it's a measurement of permeabiltiy,....a less dense rock may not necessarily be more porous, it could have to do with the mineral makeup of the rock. But generally speaking when it comes to live rock, density and porousity will tend to correlate....

The Lbs/gallon rule for LR is #1, totally vauge and reletive to a great deal of factors, and #2, as far as I know an imaginary number dreamed up by somebody somewhere way back in reefkeeping and heas been passed along from one hobbyist to the next until it became a "standard"....I have yet to see one single study or anything even close of that nature that actually suggests that there is a minimum amount of LR necessary for a reef tank.

My suggestion would be to get the amount of LR in the shapes and sizes you need to aquascape the tank the way you would like it....the less dense the LR, the better for biological purposes....



No worries...I don't think anybody will ever de-throne Nikki for the title of bulletinboard NERD....:lol:

MikeS

Thanks for that reply :exclaim: I can only speak for myself but as a novice reef keeper a reply like yours is quite helpful for beginners like me who sometimes get intimidated with the "nerd" talk

btw, I mean no disrespect to the "nerds" in this hobby

 

[MikeS]

Thanks for that reply :exclaim: I can only speak for myself but as a novice reef keeper a reply like yours is quite helpful for beginners like me who sometimes get intimidated with the "nerd" talk

Well. reefkeeping is a complicated hobby...to be sucessful long term there is lots to learn about biology, chemistry, physics, ect...it's definately overwhelming when you first get into it... There are so many ideas, disciplines, theories, ect out there to the hobby. My advice...research as much as you can. Forums like this are great, you'll get good advice and have access to good information, but be ready to get differing views and occasionally an oveload of information...:lol: Just take it one step at a time, and soak up the basics...

btw, I mean no disrespect to the "nerds" in this hobby

I'm sure Nikki will forgive you....:badgrin:

MikeS

 

[Krish]

Poor Nikki:lol:

 

[MikeS]

Poor Nikki:lol:

Poor Nikki nothing....:lol: If I was on the recieving end of this, don't even think she'd hesitate to spike that ball over the net....I have to take my shots at her when they present themselves...:lol:

MikeS

 

[balogh03]

personally, i like the look of alot of LR in a tank....to me it looks more natural. could there every be too much LR in a tank? i would think that anyway you go, the more the better as long as it still fits your personal aquascaping needs.

 

[MikeS]

As long as it doesn't inhibit flow, and provides adequate swimming space for your fish, it's ok