Do I need live rock?

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Aquarium Advice Activist
Aug 24, 2009
New Jersey
Hi everyone, I'm just starting out with a saltwater aquarium, so nothing big planned for now. I'm looking to keep a clown or two and maybe later on progress to corals. Right now I have a 30 gallon glass tank with a HOB power filter. The lighting is a standard baseline flourescent hood.

The tank is filled with 20lbs of aragonite live sand and about 6lbs of live rock straight from my LFS. The sand has been in for about a week, and I just bought the large piece of live rock yesterday. My question is, Do I need to add more live rock? I know everyone suggests using at least 1 pound per gallon, but is it really necessary for a FO/FOWLR system? The reason I ask is because one of my neighbors has a saltwater tank with a hippo tang that he has had for over 7 years, and he has no live rock or even sand, just some sort of gravel. Another thing I've read of is using mostly base rock (cheaper) with a few pounds of live rock. Would that work?

Thanks in advance, atte
No, it's not necessary. FO (Fish Only) systems are completely manageable with no live rock at all.

Do consider your choice, however. If you do wish to ultimately make a reef tank out of this system, it is much easier to add the rock up front and cycle it all together before you get any inhabitants. I understand the costs involved, and not trying to discourage you, as it is totally possible to convert from FO/FOWLR to Reef in the future, it's just easier to do the rock work upfront is all.

Oh, and Welcome to AA!
I agree, rock is not needed, but it does have benefits like breaking up of territory, hiding places (especially for inverts), hosting beneficial bacteria, sleeping spots, neat (and sometimes) bad hitch hikers. The above Neilan mentions too.
If you are looking to save some cash go with base rock since you already have LR. The LR will help to seed the base rock.
I also like the rock because I can aquascape it to make caves, walls, and other formations to simulate the critter's natural habitats.
I agree you really dont have to have it but IMO it is the way to go. LR, a skimmer and some PH`s to blow the water around and that`s all the filtration you need.
I used BR and then added LR to cut down on costs for my setup, and it worked fine. It took a while but it is all LR now. As others have stated you don't necessarily need it, but it is nice to have. I have a FOWLER system and couldn't imagine not having the rock to give my fish somewhere to hide and play!

Thanks for the prompt responses! I think I will go ahead with just adding some more base rock. Here's a pic of the LR that's in there right now, it has some great coralline growth. It seems like its bleaching a bit on the side but it should be fine. Since I used cured LR and LS, will I really experience a cycle? So far ammonia has been 0 except for very low on the days I added the rock and sand.
It will help but might not be quite enough to eliminate the cycle. Just keep adding that BR and you`ll be good to go with the tank.
As a future note: When you do decide on corals remember that they need alot more light then a FO system. That goes for anemones too.
I`m going to add just a little to etunes post. BR is rock that`s not alive but can be live over time in your tank.
Thanks for the heads up about the lighting, thincat. It will be quite a while before I even attempt corals, at least a year, but I planned on having to do upgrades later on anyway.

I will go ahead and get some base rock for the tank. Would the 15lb box from Marco Rocks be enough, or do I have to spring some extra for the 25lb? Here's the link.
Well, the rule of thumb is 1.5-2lbs per gallon, if you are going to be using the rock as your source of filtration. So.. in this case, if you just want the rock for show, and are going to be using another source of filtration, then i'd say sure, go for the 15lb box. But if you are looking to use the rock as means of filtration, then go with the 25lb box. How much rock do you currently have in the tank?

So just think, if you're not really on a budget, then to completely setup your means of biological filtration with live rock, then you are going to want 40-45lbs of rock, minimum. Anything less, and you may be taking a chance on whether or not the rock can keep up with the bio-load of your inhabitants. But like i said before, that's all depending on whether or not you are running a separate source of filtration, and not just filtration from the live rocks.
Depends on the density of the rock. If it is very porous like figi, you will need less, if not porous and very dense like carribean, you will need more. 1-2lbs. per gallon is good IMO. I would get about 25lbs. of base rock and 5-10lbs. of live rock and add more if needed.
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