Coral Density

[bobvitas]

I haven't seen anything related to this idea, but then my search skills tend to be lacking. Let me explain the situation, and then ask the question.

I have a 55 gallon reef tank. All water condition parameters have been excellent for over a year, and except for a little weird algae in my Skilter, the aquarium chugs along quite well. I have about an inch of live sand in the bottom, and about 110 pounds of liverock adding to the natural filtration. Water movement is accomplished by the Skilter (mainly for topwater movement and mechanical filtration, about 200GPH), two internal powerheads (each about 100GPH), and the dedicated protein skimmer (about 200 GPH). No sump yet, but I have a used 20L that is ready to become one. Lighting is simple at this point... about 150W worth of fluorescents (2 50-50 and 2 actinic). Inhabitants are listed below, after I ask the question.

Now for the question. I have seen pictures all over the place of nanoreef tanks that are packed with liverock and coral specimens. I have also seen larger tanks in a similar state... packed with liverock and corals. They look really nice, but I have a general question about the density of life in a successful reef tank. By that I mean, is there any sort of guideline or formula for how much coral can be housed in a given tank, before the tank collapses from bio-overload? For freshwater tanks, as an example, they say no more than one inch of fish per gallon of water. I've seen estimates for saltwater tanks that say no more than one inch of fish per two gallons of water. But what about corals?

Here's my inhabitants list. I was wondering how much more I could safely stock in my 55gallon setup:

NON-CORAL
1 Spotted (pajama) cardinalfish
1 Citron Goby
5 turbo snails
10-12 zebra hermit crabs
2 Feather dusters

CORAL
1 Green cup coral (about 3 inches across)
1 Green Star polyp (about 5 inches in diameter)
1 Rabbit Ear Leather (about 6-8 inches tall)
1 Green Button polyp (about 5 inches across)
1 Fat Button polyp (7 polyps in the colony)
2 frags of Yellow Star polyps (each about 4 polyps)
Lots and lots of Brown mushrooms
3 humungous metallic green mushrooms

The entire setup reaches from the sand bed to about 2/3s the way up the aquarium... mainly so that I can do water changes without exposing the upper polyps.

Given that the tank has been running with little more than regular water changes for over a year, I'm reluctant to "mess with success." However, it would be nice to know how much more I can stock in it.

Bob
January 21, 2007

[harman]

First welcome to TRT. As far as corals go they do not put much bio load on a tank so you would not have to worry about to many of them. Also uncovering polyps for short periods of time will not hurt them, A lot of corals get uncovered in nature during low tide so if you put some corals up higher they would be ok. And as you already know regular water changes the right kind of lightning and as most of us do, run a big skimmer is the best way to keep a healthy tank.

[leveldrummer]

welcome bob, and i agree with dave, corals dont usually produce so much waste, the same with your snails and shrimp, the fish are the main contributors to waste, thats why most reef tanks are stocked very lightly with fish. the only way over stocking with corals can be bad, is when they start using biological warfare, releasing toxins to kill their neighbors. if you dont skim that out, or run carbon and such. it can kill corals which will then decay in the water and can polute the water pretty nice.