Live Rock... I still don't understand...

[DavidG1966]

why is the calculation lbs per gallon. Shouldn't it be lbs per bio load. For an exagerated example if I have one clown fish in a 100gal tank why do I need 100 - 150 lbs of live rock? Wouldn't 30 or so lbs be enough?

 

[DavidG1966]

Shouldn't the calculation be more like this.... inch of fish x gallons of water per inch of fish x 1.5. So if you have 10 inches of fish and you need 5 gallons of water per inch of fish the amount of rock you would need would be 10 x 5 x 1.5 or 75lbs or rock irregardless of tank size?????

 

[Gudwyn]

I think it's more about how much "looks good" in that size of tank.

Also keep in mind that the recommendations seem to be targetted at gulf rock which is much denser than pacific rock. I followed the recommendation of 1-1.5 lbs per gallon with pacific rock and had to leave a bunch out. Probably 0.75-1lb of pacific is the same size as 1-1.5 of gulf rock.

 

[DavidG1966]

like i said thats why I think the common calculation is wrong. For "Filtration" purposes... Not "Looks". The calculation should be inches of fish x gallons of water per inch of fish x lbs of rock per gallon. Why is bio load never taken into account. Noone ever seems to ask about bio load when giving advice as to how many pounds of rock are needed. Again... I am talking about filtration and not looks. Thanks for the reply Gudwyn! Anyone else??? What shoud the real calculation be??????

 

[stingers81]

its just a rule of thumb

most tanks fit into that range

 

[DavidG1966]

yes i know its the rule....... thats why I am saying the rule is wrong! It should have nothing to do with tank size. It should have to do with bioload. for example if i follow the rule. If I have one clown fish in a 50gal tank I need 75lbs of rock but if I move that same fish to 100gal tank I now need 150lbs of rock. The rule is majorly flawed and should not be used when giving advice in my opinion. Thats why I think it should be inches of fish x gallons of water per inch of fish x lbs of rock per gallon. Isnt that better advice to give? Some people are spending way to much money on rock due to blind advice.

 

[d4a2n0k]

So then tell us how much rock we need per inch of fish then. Do you want to setup something with your money to find out how much ammonia a 5 lb rock will take in a day?

You are taking this too seriously.

 

[frezel]

put 30lbs of rock and 1 clown fish in a tank , and you will see how bad it looks, having to much live rock never hurt, having to little can be a problem, because you know you will have more than one fish or one coral, its just the nature of the beast. Plus rock is used as decoration and it will look goofy with that little rock in a big tank.

 

[Fuegofish777]

ya it sounds like you're taking this personally....i could be wrong though. also, think about it. anyone asking how much rock to put into a tank tends to be a begginner. alright, so lets say they get one fish so they only need 15 lbs of rock or whatever your equation calls for. how long do you think it will be before they get another fish. ok so then they have to add so much rock for their new 4 inches of fish. then that h to cycle or maybe not but they have to reaquascape. then a month later they buy another fish thats 5 inches.. now they have to buy more rock and redo it all again. dont you see...its just too complicated of a process. you could say that you should know what your going to get before you buy it but thats just not realistic. things come up and change all the time, especially from newbies. i would know i did it and still do every now and then.

 

[DavidG1966]

I'm sorry... but I think this is pretty serious... New people come to this forum everyday for advice from the 'experts' and are getting bad information on one of the most important and costly parts of setting up. The thumb in the rule of thumb seems broken to me.

 

[davidcalgary29]

<a href=showthread.php?s=&postid=6561076#post6561076 target=_blank>Originally posted</a> by DavidG1966
yes i know its the rule....... thats why I am saying the rule is wrong! It should have nothing to do with tank size. It should have to do with bioload. for example if i follow the rule. If I have one clown fish in a 50gal tank I need 75lbs of rock but if I move that same fish to 100gal tank I now need 150lbs of rock.

That's fine, but I know no one who maintains this size of a tank with only 1 small fish (and no inverts, corals, etc.). The above-quoted "rule" is valid, IMO, for those who want to maintain minireef systems with no other form of biological filtration...and not single-species tanks. I've seen quite a few setups which do not rely on live rock for biological filtration, but I think most reef enthusiasts want to recreate a complete marine environment, and not just maintain a large container for one individual.

The rule is majorly flawed and should not be used when giving advice in my opinion. Thats why I think it should be inches of fish x gallons of water per inch of fish x lbs of rock per gallon. Isnt that better advice to give? Some people are spending way to much money on rock due to blind advice. [/B]

I'm not sure I follow this. Can you elaborate?

 

[DavidG1966]

elaborate.... rock is suposed to be for filtration. The accepted rule of thumb is 1 - 1.5lbs per gallon. So.... given that rule I would need different lbs of rock for the same bio load in different sized tanks which just not sound logical to me. Given the same bioload I think I should need the same amount of rock irregardless of the size of the tank. If I have 75lbs of live rock in a 50gal tank why would I need more rock with the same bioload in a 100gal tank????

 

[IanInDC]

Yeah, I agree it's pretty silly for a bunch of people who blew $X thousand on calcium reactors, wavemakers, etc. and $x hundred on 4 inches of coral to say someone with a legitimate question is "taking something too seriously."

Especially since he has a pretty good point.

But DavidG1966, I think the problem is, the surface area of liverock -- what really determines the filtration ability of rock -- is pretty much impossible to determine: even a more approximate estimation of cubic volume is almost impossible, and that wouldn't be very relaible anyway. Add that to the fact that very, very few people actually err on the side of less fish, so most of the time you're going to end up matching up the maximum amount of fish for a given tank.

Also, for the purposes of simplicity of communication, bioload-weight would be so much more complicated than volume-weight is, you almost couldn't have a conversation about aquascaping without complicated algebra.

 

[dt90gt]

<a href=showthread.php?s=&postid=6561254#post6561254 target=_blank>Originally posted</a> by DavidG1966
elaborate.... rock is suposed to be for filtration. The accepted rule of thumb is 1 - 1.5lbs per gallon. So.... given that rule I would need different lbs of rock for the same bio load in different sized tanks which just not sound logical to me. Given the same bioload I think I should need the same amount of rock irregardless of the size of the tank. If I have 75lbs of live rock in a 50gal tank why would I need more rock with the same bioload in a 100gal tank????

Dude, I'm sorry, but read your posts before posting, and don't use seven ????????? at the end. People realize it is a question.

Rock is not JUST for filtration. Rock is there to look at something cool that also serves as a filter. The accepted rule exists for one purpose: People want to have the maximum bioload possible for a given tnak size. The only way to have the maximum bioload for a tank is to have a large amount of live rock, while still maintaining space for the fish to swim. That amount of rock is usually 1-2 lbs per gallon. 1 pound of less dense rock, 2 pounds for more dense rock.

If I have 75lbs of live rock in a 50gal tank why would I need more rock with the same bioload in a 100gal tank

You don't. Just don't add any more fish for the life of the tank. Oh wait, that is probably a stupid idea and never going to happen.

So go buy a 100 gallon tank, put 1 clown and 1 5 lb rock in it, and tell us if it looks stupid.

 

[stingers81]

David....rule of thumb is just an easy way of explaining things complicated things

sure you can use your equation and be accurate...I guess....kinda hard to follow but what happens when someone wants to add more fish??? now you need to get more rock....new fish and new rock would might be too much of bioload and might start a new cycle....

the safest way to go that will work and look great is 1-1.5lbs of LR...its that simple

 

[stingers81]

also...
people upgrade their tanks to bigger sizes so they could get more fish/bigger fish in there

you will need more rock that way again

 

[DavidG1966]

So what you are saying is when I move my 2 clown fish and clams from my 50gal to a new 100gal tank I need to get another 75lbs of live rock also?

 

[d4a2n0k]

I dont know for sure but its pretty safe to say that not all rock will filter the same amount of water in the same amount of time. There is probably a difference in filtration between Fiji, Kaelini, Gulf etc. rock. The 1-1.5 lbs per gallon is just a general guide. The only way to tell is to setup equal tanks and drop some ammonia in each tank and see which rock filters it the fastest. Who wants to waste their own money on this test? I know I dont.

Now your argument about moving moving 75 lbs of rock from a 50 gallon to a larger tank. Of course if you move all the same animals over, you will not need more filtration. But, who moves to a larger tank without adding more livestock? Isnt that the whole point of upsizing? Besides filtration, the rock is also for placing corals on. If you upsize tanks and bring all the same livestock over, you are not really adding anymore places to place corals, unless you are keeping only Brains and the like which can sit in the sand.

I'm sure you can get by with less rock but as with everything else in this hobby, more is better. When you are walking a fine line, things can go wrong quickly. Its not like the additional rock costs all that much more in the grand scheme of things. I mean you can get good live rock these days for $2-3 lb. The risk of getting by with less rock just doesnt seem worth it to me.

 

[Chckrbrd Wrasse]

If any ones interested here is an excerpt from a very good article by by J. Charles Delbeek B.Sc., B.Ed., M.Sc.

The amount of live rock required in a system is difficult to assess. The general rule of thumb is to place the rock such that it takes up about 1/3 of the visual volume of the aquarium. Using estimates of mass to determine how much rock is required are crude guidelines at best. The reason for this is that live rock can vary greatly in density. To fill a 65 gallon tank 1/3 full of a dense type of rock may require 200 lbs., but if a very low density rock were used only 100 lbs. may be required.

If you want to read it all you can find it at this web address.

http://saltaquarium.about.com/gi/dy...=http://www2.hawaii.edu/~delbeek/homerf1.html

 

[GreyG35]

I tend to agree with that assessment, David -- it seems like everyone assumes that you will load the tank to max bioload with fish (using whatever inches per gallon rule is being quoted at the moment). I think it's mostly a ploy to sell more rock.

That said, I imagine it's better to have too much rock, rather than too little...I'll bet most people are guilty of overstocking, not understocking their tanks, and the LFS people know it (and maybe encourage it).