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TRIGGERMAN

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It really depends on how dense the rock is but if we are talking about cheap dense "base" rock then I 100% agree with reaper and gochi 200-300lbs will be ideal for that size system. I personally like rock that is lighter and more porous. Try to get some of that also it is good for sticking frag plugs in when you start getting corals. The more holes the better.
 

Dre

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It depends on how you want your tank to look .The rock per gal. quote is BS.
 
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Imbarrie

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If you want an open structure you should go with less bulky rock. If you want a wall type structure go for traditional rocks.
Simon has a thread called My Maldivian Puddle with the coolest tank I have seen built. He is not even close to the Lbs/Gallon "rule"
It's more about the look and the livestock you want.
The more rock you have the better buffer you have for bacteria. If you go light in the DT you could stock the sump with rock to make up for it.


Sent from my iPhone using Reefs
 

AlohaTropics

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Yes, there is no true lbs. per Gallon "rule". Its all about how much waste your tank is producing. If you are stocking your tank to the brim, you will need more rock so you can colonize more Nitrifying Bacteria. I would simply start with aesthetics. Make it look the way you want it to look.

As suggested, Rock that is more porous and less dense is usually preferred because they can colonize much more bacteria and they weigh less.

If you really need a # to work with, I would say a minimum of 150lbs. But again that number is subjective to the density of your rock.
 

Dre

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isn't the 1 to 2 lbs per gal. cause if it is than the recomendation i see here seem to conclude that lol
Rules and recommendations are made up and broken every day.What i'm saying is, build what looks good to you.You don't need alot of live rocks to have a successfull reef.This is true for people how use styrofoame reef structures and man made reefs structures.So you tell me where does this lb. per gal. come in ? For example home made rocks make beautifull reefs no doubt, and Slate Rocks.Besides too much rock can make tanks look packed and unsightly IMO. Check out the Tank Threads you can see some very beautyfull tanks .Oh! and check out Sanjay's tank one of the best and not a lot of rocks either, besides corals and fish do need their space .
 

Simon Garratt

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lol...

its amazing how the same questions crop up across the hobby boards on so many occasions....

so to save me re-writing a load of stuff out...heres the responses i gave on another forum regarding LR calculators and other related issues..

Hope it's of help..

Gawd this is like that appaling watts per gallon theory that was banded about for donkeys years..

Sorry, but I dissagree with any calculator that quotes X weight of rock per Y gallon.

You cannot possibly give or recommend a weight ratio once youve factored the massive differences in density of the many various rock types available today versus the volume of 'space' that that particular type of rock takes up in an aquarium.

We've moved a long long way since No3 control was linked to the 'volume' of rock in a system, with many systems actually proving that under good flow conditions, far less rock than normaly quoted, mixed with a good flow rate can 'and does' herald far better results over the long term, freeing up more water volume which helps the dilution factor of X amount of nutrient entering the system, not to mention giving greater chemical stability against depletions and adverse accumulations, whiilst at the same time having far less impact on the hydrodynamics of the system...Less disruption to free flow, enables you to put less energy into the tank to maintain higher velocities. Higher velocities = more waste/food kept in susspension for longer periods so it can either be captured by corals/fish etc or removed from the nutrient chain by other methods ie skimming.....rather than leaving it all in the hands of bacteria.

The more you increase the volume of rock against the water volume, the more disruption you get to any flow you try to create within that volume...the more disruption you get, the lower the flow rate gets unless you chuck more energy at it, and the more waste settles out to break down..so its not uncommon for tanks with a high proportion of rock to suffer high No3 for no other reason than they are effectivly clogged from a hydrodynamic standpoint..basically they become waste traps.

The problem with linking No3 accumulation to LR volume is that it encorages people who are suffering no3 buildup to add 'even more' rock to a system that may already be in a state of hydrodynamic suffocation...which can then make the situation worse, not better.

In my experience. No3 issues have very rarely had anything to do with a 'lack' of LR. Its nearly allways (ruling out obvious stuff like overstocking/poor feeding lack of skimming etc) poor flow, or too much rock or poor rock arangement that is strangeling the system.


I think in this day and age of reefkeeping, we should use a far more 'scientific' approach which factors all the modern principles of flow velocity and known benefits of increased diffusion through open structures....and that would be to look at the volume of 'space' that is taken up by any rockwork present, rather than its weight or displacement...(For example: bluestone is incredibly porous and light compared to say indonesian. so a piece of bluestone may take up a physical area equivalant of a full gallon whilst the same 'weight' of indonesian may only take up half or less of that space).

Personaly i like the following as a modern guide becouse ignores weight as a measure of scale which is variable according to density, instead it factors in the whole range of considerations from free water volume and chemical stability, to swimming space for fish and decent hydrodynamic function of the entire volume...ie no more than 1/4 to 1/3 of the total physicaly veiwable free water volume of the aquarium should be taken up by rockwork regardless of density.

Another words...If you took all your rock and placed it in a pile at one end of the tank from base to surface and front to back, that pile or volume of rock (including the gaps) shouldnt extend any further than 1/4 to 1/3 the length of the tank. what you do with that rock after that point is entirely up to you in terms of arangement, as long as you factor things like disruption to gyre flow patterns by having rock touching the glass sides etc..Regardless of how you arrange it, you will still maintain that 1/4-1/3 differential.

Then from another member:

The purpose of the calculator was only to give newbies a rough idea of how much rock to purchase and lets face it most people could do the calculation in their head. Because LR is expensive there is a tendency for newbies not to put enough LR in the system, not the other way round and it's a very common question on here.

Si you raise a lot of valid points, but when you say you like the more modern approach aren't you arguing apples and pears. I really do wonder how different is 1/3-1/4 volume of tank to 1/2 kg per gallon? Both are measurements of the amount of LR per volume. Both at best are only rough estimates, but LR is sold per kilo. So would prefer to use the latter.

You can see a question on here...
How much liverock do I need?
How big is your tank?
200 litres
You need enough to fill up 1/4-1/3 of volume.
Errr........so how many kilos do I need to buy?


Response.

Im just highlighting the fact that going by 'weight' is a pointless task becouse you arnt dealing with something that has a fixed density....Its like comparing oak and Balsa and every other type of wood in between.

so to answer your question quite simply..

How much liverock do I need?
How big is your tank?
200 litres

Ok, but what are the dimentions...?

erm, 48x15x18

Ok then, You need enough to fill 1/4-1/3 of that volume. or an area of 12x15x18 up to 16x15x18

Gets rock out of LR vat stack it on the floor in a pile till you get to those rough dimentions.....

There you go sir...lets weigh it and work out how much that will cost according to its weight.


The benefits here are quite clear....you are working first and formost with the amount of 'area' taken up within the tank by the rock you then put in it, regardless of its density...


As a 'standard' method, this then brings all tanks into line as a healthy starting point regardless of dimentions and regardless of the rock type/density used....if you go by weight alone using some of rock types available today, then that volume could vary masssively which then throws the whole thing out.

Hell you could even convert it into cubic feet if you wanted.

What people need to ask is 'why' the x weight/gallon system was even invented.....It certainly wasnt based on methodology....It was actually based on the fact that when ordering/shipping LR, its far easyer to work in 'weight' rather than 'volume' as a standard...this doesnt mean its right in practice though when it comes to 'function' within a tank. The two principles are very different. so its down to co-operation between the buyer and LR sellor to work out the cost of the LR they need by using both those systems to reach an end decision.

Personnaly, knowing from yrs of experience just how much the volume of rock relative to water can affect a system, my priorities rest firmly on the x volume method relative to tank size rather than weight, becouse ive seen too many systems over the years that are way way over loaded with rock of a low density causing clogging, poor circulation and mounting difficulty in controling water quality later on.

Trying to convince someone to remove LR to help clean up a system, is a damn site harder in my experience than telling them to 'add' some more. becouse of that ingrained appaling x weight/gallon system that was adopted many years ago..Just becouse its been done for years doesnt make it right by any means, especialy when that method is based on shipping, rather than function.


from another member new to reefkeeping.

well being a noob myself I found the calculator very helpful. I didn't have a clue how much live rock I needed and didn't want to start another "how much rock" thread.

So it may not be 100% accurate but it is a helpful guide (for me anyway.)

It told me I needed 50kg for my 100 gallon 4x2x2 tank so that is exactly what I ordered! Is this too much or too little, I haven't a clue but it must be in the right ball park surely?

Response..

Yes your right, it probably does put you in the right ball park if your lucky and have an average density rather than an extreme of high or low...

Im not saying here that the calculator is 'wrong'...Im saying its a flawed outdated method that leaves alot to be desired. but as with most things in our hobby. change comes slowly and old habits or standards are difficult to change or shed..

equally lazyness is a factor...people want a quick strait answer to all questions these days regardless of how obscure or variable the truth may actually be...

Sitting down with your dealer and picking out the rock you want and measuring how much space it takes up is a case in point...It takes time and effort on the part of both parties, (or getting the dealer to do it over the phone in the case of online ordering)....Personnaly i dont know any decent dealers who 'wouldnt' be willing to do this 'IF' you ask nicely, and explain that you are looking at volume rather than weight as a measure of how much you need.

In truth isnt that what the hobby 'should' be all about though...taking your time, playing with things and learning as you go... Picking out and arranging your rockwork is the very start of a journey, so why try and look for the fastest and easyest method regardless of how flawed and outdated it is, and then miss out on all that fun and learning...

I know which id prefere personnaly.

The point im making here is that you as a novice have imediately been led down an outdated path (even though it may have worked for you in this instance)...simply becouse someone has had the bright idea of offering you a quick answer to a question that doesnt actually have a real answer..ie how much 'weight' of rock do i need for x volume of water...


it went on from there a bit more but those were the highlights...

just my personal opinion though obviously.


regards
 
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seldin

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New York
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First thing, as stated no hard rule. Good rule of thumb is 1-1.5 lbs per gallon of water. What I like to do, is take rock out of tank, and drill about size of 1/4 inch holes all through out rock. Then, my plugs have holes all through out rock and I can move frags around tank. So hole size drilled is the size of the plug end that will fit in rock.

I love doing this, because rather than find a spot where the frag will stick to rock, I can place frags anywhere I want. I then move frags around tank, depending on how they like where they are seated.

This also improves on bacteria, etc., because the holes help with filtration.

As far as ratio of live rock to base rock, yes base rock should cost less. However, MR has reefers constantly going into and out of the hobby, so you can find live rock on here going for great prices. So you can buy live rock cheap. Otherwise, you can also just get a couple of pieces of live rock fully encrusted from a reefer or LFS and place with base rock in tank. This is called seeding, and your tank, will eventually all become live rock...

A great trick I recently learned from MR, is that you can take a razor and scrape some coraline off of live rock in tank, and this seems to enable the coraline to be disbursed through out tank and makes rock develop live rock coraline a lot faster. This does work well.
 
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