Livening up Your Tank with Live Rock
Live rock is perhaps the single most important factor in keeping a nano reef, or any captive reef. Live rock provides natural biological filtration in the form of microscopic bacteria living on and within the rock. Live rock also breaks down nitrate deep within the rock in anaerobic conditions.
Live rock is usually coralline algae-covered rocks or dead calcified coral skeletons. Despite its name, live rock is not part of the living reef. It's actually rubble from reefs either long dead or broken free during storms. Although live rock is no longer part of the reef, the rock continues to host a variety of life.
The bright and interesting colors you see on good live rock pieces are coralline algaes, a beneficial encrusting algae which helps against troublesome algae by outcompeting it for nutrients. These colors, along with the attractive shapes of live rock, make live rock very aeshetically pleasing for the reef tank. Even if you elect not to go for a reef tank, live rock will give your tank the "reef" look.
When shopping for live rock you'll likely find multiple varieties, given names specific to their native locales. Some of the most common varieties are rocks that hail from Fiji, the Tonga and Marshall Islands, the Caribbean, and Florida. The best live rock is porous and lightweight, allowing maximum surface area for bacterial colonization. Try to avoid the bulky, heavy pieces.
You'll also see live rock offered as "premium" pieces. Usually these are rocks teeming with good algaes and life, often completely red or purple from coralline growth. Obviously, these are higher priced because they are prettier and supposedly give you more bang for your buck with greater microorganism count.
The important thing is to pick out several pieces that you really like. Be sure the live rock is cured. Cured live rock is rock which has sat in the LFS' curing tanks for a month or two, eliminating most of the natural die-off of organisms which can pollute your tank. Uncured live rock can cure in your new tank for up to a month and a half and will require frequent water changes as the rock establishes a new bacterial base.
Two or three large 3+ pound pieces are good for a ten gallon nano. I began mine with only nine pounds. I now have a total of twelve pounds. Often you'll buy coral already secured to a piece of live rock so keep that in mind as you select the rock and make your future plans.
It's important to place your live rock securely on the substrate. This means you make sure it does not wobble enough that there is a chance for it to fall, potentially into the glass. Of course, that goes without saying, do not lean live rock against the glass. I've learned the hard way that it's best to use zipties or other means of securing two pieces together if you lean them against one another, vertically. It's no fun righting a fallen piece of Tonga branch that already has a clam attached to its supporting rock.
Your live rock can go straight into your tank once it's ready and the powerheads are running. And if you've already laid down your substrate, don't worry about placing your rock on top -- just be sure it's firmly in place in the sand and won't collapse or fall into the glass.
Follow the directions on your package of salt mix and prepare your first batch of synthetic seawater, checking the salinity with your hydrometer or refractometer. Aim for a number between 1.022 and 1.026. I keep my reef at 1.022-23. The important thing is keeping the salinity constant. Remember specific gravity is relative to temperature, so be sure the water is heated to 78-80 degrees when you check.
A Word about Lighting (Note: If you're keeping fish only and live rock, you can skip this part.)
Good lighting is as important as live rock for reef keeping, if not more so. Without adequate light, corals will ultimately close up, wither, and die. Unfortunately, reef lighting is very confusing for the saltwater beginner. Those "Marineglow" and "Coral Sun" bulbs at Petsmart and Petco will not light a nano reef, despite the claims written on the box. Unless you have a 1, 2, or 3 gallon tank, a single bulb will likely not allow you to keep even the hardiest of corals.
Corals do best in lighting in the 6700-10,000 kelvin range. Kelvin is a measurement of heat, and the temperature yields a certain color on the spectrum of visible light. Do not confuse this with nanometers, which measures the wavelength of light color in the visible spectrum.
Okay, let's break it down...
- 6500-6700 K: This range is ideal for freshwater plants and also good for corals. This is a soothing, almost institutional white.
- 10,000 K: Generally better lighting for corals. 10,000 K offers a very crisp, bright, white light.
- Actinics: The blues of reef lighting. Think of a blue flame... much hotter than an orange flame, right? Same applies here for lighting. The kelvin rating is much higher for "actinic" blue light. Actinics, when combined with 6700 or 10,000 K bulbs, creates a very pleasing look for the reef tank. Most light fixtures offer a 50/50 mix, which is an actinic light coupled with a white light.
The benefit of employing a ten gallon reef is that you can easily have approximately ten watts of light per gallon, which is enough to keep almost any nano-appropriate coral or clam. I use the 96 watt Coralife quad light 20" fixture with 50/50 bulbs. This kind of fluorescent lighting is called power compact, a regular fluorescent bulb which is bent in half to double lighting power.
Power compact bulbs are best if changed every 6-10 months. The bulb will continue to illuminate, although it loses a lot of its punch over time and can eventually weaken your corals if not changed.
If you're planning an unorthodox nano tank, like a large bowl or a vase, Coralife also makes a 10 and 20 watt 50/50 compact fluorescent bulb, ideal for micro or "pico" reefs. These bulbs screw into lamp ballasts like a normal incandescent light bulb.
Patience is Key
You have your tank up and running, the live rock has been introduced, and your heater light is on, keeping your water in safe tropical temperatures of 77-82 degrees. Now it's time to sit back and watch all the cool life that will emerge from your live rock.
Lighting is not needed during this time, and many hobbyists believe it's best to go dark while your cured live rock goes through a phase or two of die-off, in order to keep nuissance algae down. So now would be a good time to buy or order your reef light. Three excellent online retailers which offer whole reef lighting kits are hellolights.com, drsfostersmith.com, and bigalsonline.com.
No matter how "cured" and life-rich your rock is, you will go through a period of die-off. Algaes may peel off in brown ugly lumps, or a dead starfish may suddenly appear in your tank, having floated up from the depths of a rock. During this time it's important not to add any other life. Trust me, in one or two weeks, your tank will be ready to host your first little lifeforms, called the "clean-up crew."
If you're buying your live rock piece by piece, buy your largest pieces first and try not to add any crabs or snails until they've had a chance to establish themselves.
All live rock is different. You may have a piece or two that hadn't cured all the way and may have to wait up to three weeks before adding the clean-up crew, or you may be ready in three or four days. A good rule of thumb is to wait 10-14 days while checking your water for ammonia and nitrite. To be safe, you don't want to add any crew members until ammonia and nitrite fall to zero.
Fortunately, "cycling" a marine tank is nowhere near as boring as "fishless cycling" a freshwater. You'll see clear, tiny flea-like critters on the rock and glass, which are called amphipods and copepods. These are very desirable and provide essential fatty acids to your fish when they are consumed. You'll also see a small bristleworm or two, maybe a featherduster, tiny little white starfish, and if you're really lucky, a coral may have stowed away.
These forms of life are called "hitchhikers." They can be good and bad, and there are so many it would be impossible to list them all.
Copyright 2006 by Josh Day. All rights reserved. No part of this article may be reprinted or distributed to other websites without the author's written permission.