How much live rock do I REALLY need?

L

laeelin

New member
I'm talking about just for biofiltration. Not taking into account looks / hiding places / etc.

My understanding is that the filtration the live rock provides is the nitrification cycle, and that the bacteria will grow on almost any surface. Live rock is so popular because it makes sense to use it even without it's filtration properties.

Live rock is very porous and provides a HUGE amount of surface area for it's size, and thats what it bring to the table for filtration.

I hear people talk about 1lb - 2lbs per gallon, but even a beginner like me knows that there are huge differences in how porous the rock is. Dry rock (with seeding) brings a whole new problem because there it weights so much less without water. BRS has a great video on live rock.

My situation (well, the situation I'm aiming for):
90g tank.
10% water changes every 2-4 weeks.
4" Sandbed in tank for Jawfish / Gobys / Pistol Shrimp.
20g sump.
Remote DSB in a 5g bucket. (for anaerobic bacteria)
Skimmer.
High bio-load (lots of fish).
3 feedings a day. (I plan on having anthias)
​

Ignoring the sheltering needs of my fish, would I really need more than a box of Marine Pure?

Would a box Marine Pure in my sump and Remote DSB cover all of the filtration needs that we normally use live rock for?

I THINK, that I can completely ignore all of the lbs/gallon rules and simply add what looks good to me and for the shelter needs of my fish.

Am I right?
 
Those bioballs will not replace live rock and they wont be enough for the tank.
Many people seem to feel that stuff in the sump works for a while but becomes a problem later on.

I think most would say 1 pound of live rock per gallon at least.
 
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I've got maybe 50 lbs of rock in a 90 with 9 fish. The lb per gallon rule more than likely came from those who sell rock. I've read about tanks with nothing but a sand bed. Bacteria is dependent on bio load. The same amount of bacteria exist in 50 lbs as 100 lbs with the same bio load. The bacteria just spread out. There's a great thread on another forum discussing this. The science holds up, there is no golden rule. What looks nice to you.
 
rffanat1c said:
I've got maybe 50 lbs of rock in a 90 with 9 fish. The lb per gallon rule more than likely came from those who sell rock. I've read about tanks with nothing but a sand bed. Bacteria is dependent on bio load. The same amount of bacteria exist in 50 lbs as 100 lbs with the same bio load. The bacteria just spread out. There's a great thread on another forum discussing this. The science holds up, there is no golden rule. What looks nice to you.
Click to expand...

I'll look for some information on tanks with just a sand bed - it's an interesting idea for specific setups - like a Garden Eel tank.

Do you have a link to the no live rock discussion by any chance? No worries if you don't have it on hand, I'm sure google will provide ;)
 
According to BRS a 8"x8"x1" Marine Pure ceramic block will provide adequate biofiltration for a 100 gallon tank. Not recommending that but I do think using that could greatly decrease the amount of live rock needed for the main display.
 
hogfanreefer said:
According to BRS a 8"x8"x1" Marine Pure ceramic block will provide adequate biofiltration for a 100 gallon tank. Not recommending that but I do think using that could greatly decrease the amount of live rock needed for the main display.
Click to expand...

That's great to hear!

I'm not really looking to put no rock in the tank...

I just think that I should be thinking purely of the aesthetics, and the needs of the life in the tank (shelter, ledges, etc).

For my 90g, I want to avoid the "wall of rocks" - I want an aquascape closer to this:

5869329175_0cdba86e44_z.jpg

Image is from this thread: http://www.reefcentral.com/forums/showthread.php?t=2289904
 
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Pulling an arbitrary number here but to be safe I'd have at least 3/4 lbs per gallon in your DT if you're going to get bioceramic media blocks in the sump. The reason is in case of power failures, you will have next to no nitrifying bacteria in the DT and may cause a tank crash depending on how long the power failure is.

A way around this is of course to hide the media in the DT. You will have to frequently clean of detritis I assume.

736825_10101185958841034_537984815973972403_o.jpg


Example of my 30g with 1lbs to gallon ratio. bioceramic block in the sump
 
cheucklate said:
Pulling an arbitrary number here but to be safe I'd have at least 3/4 lbs per gallon in your DT if you're going to get bioceramic media blocks in the sump. The reason is in case of power failures, you will have next to no nitrifying bacteria in the DT and may cause a tank crash depending on how long the power failure is.
Click to expand...

The way most of our tanks are setup, any extended power outage we are in trouble without us taking any action. Cooling, heating, skimming are some of things I can think ok.
 
oseymour said:
The way most of our tanks are setup, any extended power outage we are in trouble without us taking any action. Cooling, heating, skimming are some of things I can think ok.
Click to expand...

Exactly... Wouldn't temperature be deadly far before the lack of filtration made a difference?

If we ever loose power for an extended period I'm going to need a generator anyway.
 
Bottom line, there are whole lot of ideas on how much rock, sand or other stuff to use.
And most any method will work as long as you do not go to far off.

Deb wise I think a 90 tank with a 5 inch bed is enough for most loads.

There is also the miracle mud in the sump way of things

And with less fish and less fish food you can reduce the waste load....
 
This is an 80 gallon 48" x 24" x 16" All Marco Rock.
I didn't weight it, but I'd be surprised if I have more than 40-50 lbs in it.

thumb_IMG_3891_1024_zpsszx74487.jpg
 
Thank you for the help everyone!

I think i'm going to order something like 30-50 lbs of reef saver from BRS.
 
If you're looking to minimize your live rock reef saver is the poorest choice. It has less surface area/weight than just about any other dry rock.
 
The 'lb/gallon' is a long held rule of thumb that traces back to the early days of the reefing hobby when most/all of the rock was sourced from the ocean and relatively uniform in terms of density and porosity. Now the sources of rock are so varied as to make any such rules of thumb essentially useless.

I think the best approach is to add as much rock as you need for your desired aquascape. Then simply keep an eye on ammonia, nitrite, etc. and add more if deficient. I have about 150 pounds in my heavily stocked 265 and have never had any problems. Also remember that any sand will supplement the bio filter.
 
I really think it depends on how much you will want to be doing water changes. And will you be okay with levels much above zero. The more sand and live rock you have the more stable your numbers can be without to much input on your part.
 
laeelin said:
Would a box Marine Pure in my sump and Remote DSB cover all of the filtration needs that we normally use live rock for?

I THINK, that I can completely ignore all of the lbs/gallon rules and simply add what looks good to me and for the shelter needs of my fish.

Am I right?
Click to expand...

You are very right sir or madam.
 
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