water to live rock ratio

MrsHaggis · 03/10/2009, 11:39 AM

I was told when I first got my tank that for a certain amount of water you need a certain amount of live rock. And I have read that on posts here more than once.

And so in my tiny little 16 Gallon tank we have so much rock it's crazy but the ratio works out pretty much as between 1 and 1.5 llbs of rock per gallon of water.

But when I look at my tank compared to come pictures that I see here I notice that some tanks have hardly any rock in them. I thought the rock aided filtration and the removal of nitrates etc?? How can some tanks work with hardly any live rock?

IslandCrow · 03/10/2009, 12:05 PM

1-1.5 lbs per gallon is the standard, but it's definitely needs to come with an "it depends". First off, some rock is more dense than others, so 16 lbs of one type of rock may take up more or less space than 16 lbs of another variety. Second, although lbs per gallon is a convenient guage, it really has more to do with bioload. As you pointed out, rock is a biological filter that converts ammonia to nitrites and nitrates, and nitrates to nitrogen gas. If you have a lighter than average bioload, you don't need as much rock. If you have a higher bioload, you need more rock. In a small tank, the difference between 1 lb/gal and 1.5 lbs/gal is much more apparent than in a bigger tank. I don't have 1lb per gallon in either of my tanks, but I keep a light bioload and I'm religious about water changes. If the amount of rock you have is visually unappealing to you, you can follow those same principles and get away with less rock.

MrsHaggis · 03/10/2009, 12:16 PM

I already took out one rock (simply to gain more space) and the effect on my tank was huge.

My bioload is pretty small - I still only have 1 fish and 4 snails....!!!!
But you are right in a small tank trying to keep the water params normal is harder than a big tank - wish I had known that before I got such a small tank!

I do a 10 litre water change once a week. I would like to remove more rock but I removed another one about 3 weeks ago and had to put it back in - nitrates rose to such an extent.......

So basically in my big tank (that I am planning now) I could get a denser type of rock (any ideas?) and I could get less than the 1lb per gallon......

Some tanks I look at have only 4 pieces of rock though......how does that work??

turretdr · 03/10/2009, 12:54 PM

I would avoid the denser rock. The more pourous rock is, the more surface area for the denitrifying bacteria to be. It might take up a little more space, but it is a lot more beneficial than a solid boulder that you find in your yard. Many people also run live rock and other mechanical filtration in sumps and/or refugiums.

djburns · 03/10/2009, 01:21 PM

Don't mean to hijack this thread but is the rule of thumb for LR based on the volume of the display tank or total volume of the display and the sump/refugium?

reefscape15 · 03/10/2009, 01:36 PM

Total system volume is what the reccomendation is based on. Really just aquascape how you want, keeping in mind how many lbs of rock you use. If you stay with at least 1lb/gal you'll be fine on standard tank filtration/maintenance, but if you go under, you will end up needing a bigger skimmer to help pull out wastes that the rocks can't handle, and higher flow

MrsHaggis · 03/10/2009, 02:03 PM

Ah, didn't think about putting some in the sump too!!

so when you do your calculations and you have a sump should you add that gallonage to the display tank gallons? Or are we just working on 1lb per DT gallon?

03/10/2009, 11:39 AM	#1
MrsHaggis Registered Member Join Date: Dec 2008 Location: St Louis, France Posts: 675	water to live rock ratio I was told when I first got my tank that for a certain amount of water you need a certain amount of live rock. And I have read that on posts here more than once. And so in my tiny little 16 Gallon tank we have so much rock it's crazy but the ratio works out pretty much as between 1 and 1.5 llbs of rock per gallon of water. But when I look at my tank compared to come pictures that I see here I notice that some tanks have hardly any rock in them. I thought the rock aided filtration and the removal of nitrates etc?? How can some tanks work with hardly any live rock? __________________ Nothing scarier than a clown!! ----------------------------- 1 ClownFish 1 SixLine Wrasse 1 Foxface Rabbitfish Mushrooms Long Polyp Leather Green Anchor Coral Zoanthids Trumpet Coral Goniopora Current Tank Info: 360 litre (95 US Gallons), Tunze DOC Skimmer 9010, Lights: Metal Halide 250 Watt and 2x24 Watt Moon Lights, Tunze MultiController 7095

03/10/2009, 12:05 PM	#2
IslandCrow Reef Monkey Join Date: Sep 2005 Location: Rockledge, Fl Posts: 5,759	1-1.5 lbs per gallon is the standard, but it's definitely needs to come with an "it depends". First off, some rock is more dense than others, so 16 lbs of one type of rock may take up more or less space than 16 lbs of another variety. Second, although lbs per gallon is a convenient guage, it really has more to do with bioload. As you pointed out, rock is a biological filter that converts ammonia to nitrites and nitrates, and nitrates to nitrogen gas. If you have a lighter than average bioload, you don't need as much rock. If you have a higher bioload, you need more rock. In a small tank, the difference between 1 lb/gal and 1.5 lbs/gal is much more apparent than in a bigger tank. I don't have 1lb per gallon in either of my tanks, but I keep a light bioload and I'm religious about water changes. If the amount of rock you have is visually unappealing to you, you can follow those same principles and get away with less rock. __________________ All opinions in the above message should be taken with 35 ppt salt. -Mike C. Current Tank Info: I have a reef screen saver on my phone, does that count?

03/10/2009, 12:16 PM	#3
MrsHaggis Registered Member Join Date: Dec 2008 Location: St Louis, France Posts: 675	I already took out one rock (simply to gain more space) and the effect on my tank was huge. My bioload is pretty small - I still only have 1 fish and 4 snails....!!!! But you are right in a small tank trying to keep the water params normal is harder than a big tank - wish I had known that before I got such a small tank! I do a 10 litre water change once a week. I would like to remove more rock but I removed another one about 3 weeks ago and had to put it back in - nitrates rose to such an extent....... So basically in my big tank (that I am planning now) I could get a denser type of rock (any ideas?) and I could get less than the 1lb per gallon...... Some tanks I look at have only 4 pieces of rock though......how does that work?? __________________ Nothing scarier than a clown!! ----------------------------- 1 ClownFish 1 SixLine Wrasse 1 Foxface Rabbitfish Mushrooms Long Polyp Leather Green Anchor Coral Zoanthids Trumpet Coral Goniopora Current Tank Info: 360 litre (95 US Gallons), Tunze DOC Skimmer 9010, Lights: Metal Halide 250 Watt and 2x24 Watt Moon Lights, Tunze MultiController 7095

03/10/2009, 12:54 PM	#4
turretdr I want to play a game Join Date: May 2006 Location: Charlotte, NC Posts: 296	I would avoid the denser rock. The more pourous rock is, the more surface area for the denitrifying bacteria to be. It might take up a little more space, but it is a lot more beneficial than a solid boulder that you find in your yard. Many people also run live rock and other mechanical filtration in sumps and/or refugiums. __________________ NO REGRETS.Every decision we make is based on current knowledge. NO REGRETS.

03/10/2009, 01:36 PM	#6
reefscape15 Registered Member Join Date: Jan 2009 Location: Elmira Heights, NY Posts: 2,812	Total system volume is what the reccomendation is based on. Really just aquascape how you want, keeping in mind how many lbs of rock you use. If you stay with at least 1lb/gal you'll be fine on standard tank filtration/maintenance, but if you go under, you will end up needing a bigger skimmer to help pull out wastes that the rocks can't handle, and higher flow __________________ A new beginning........... JIM Current Tank Info: 5g standard softie/zoa tank, just starting a 20H

03/10/2009, 01:21 PM	#5
djburns Registered Member Join Date: Jan 2009 Location: Windham Posts: 48	Don't mean to hijack this thread but is the rule of thumb for LR based on the volume of the display tank or total volume of the display and the sump/refugium?

03/10/2009, 02:03 PM	#7
MrsHaggis Registered Member Join Date: Dec 2008 Location: St Louis, France Posts: 675	Ah, didn't think about putting some in the sump too!! so when you do your calculations and you have a sump should you add that gallonage to the display tank gallons? Or are we just working on 1lb per DT gallon? __________________ Nothing scarier than a clown!! ----------------------------- 1 ClownFish 1 SixLine Wrasse 1 Foxface Rabbitfish Mushrooms Long Polyp Leather Green Anchor Coral Zoanthids Trumpet Coral Goniopora Current Tank Info: 360 litre (95 US Gallons), Tunze DOC Skimmer 9010, Lights: Metal Halide 250 Watt and 2x24 Watt Moon Lights, Tunze MultiController 7095