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Coral Reef Tank Basics!

Clownfish in zoanthids

This is a picture of my Mocha Storm and Black Storm clownfish in my reef tank.

This is a picture of my Mocha Storm and Black Storm clownfish in my reef tank.

Coral reef tanks have a bit of a learning curve to get over in the beginning. It is really hard to pick up and get going without doing proper research. My goal is to be able to give you the basic information to begin that research!

Once you get these down and pick up a routine with the tank, I think things become a lot easier. You can get really far with the basics.

Clownfish pair swimming through zoanthids

First I would like to talk about the water aspect of keeping a coral reef tank. The water requires a few things.

1. Proper salinity

2. Proper Temperature

3. Good flow

4. Filtration

5. Stability

Salinity should almost always be around 1.026 specific gravity. For tropical reef tanks, temperature should be between 76-80 degrees with a sweet spot around 78.

Flow and filtration are where things start to become more grey. They depend on what you plan on keeping in the tank. We typically recommend around 10x tank turn over per hour. So a 50 Gallon tank will want close to 500 GPH water flow. Remember, most coral do not enjoy direct flow.

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Filtration is mostly up to the reef keeper's personal preference and how they can work it into their routine. I prefer mechanical filtration and live rock as my main sources of filtration. In addition, water should be filtered with an RODI unit before salt is mixed.

Finally, stability has to do with keeping everything the same or changing at a slow consistent pace. Parameter changes will make some coral close up or sick. One of the best items I ever purchased was an Auto Top Off System. This fills the tank with fresh water as the tank water evaporates. I think this is one of the first steps I took when realizing how much stability matters.

The video above shows clownfish swimming through their host colony of zoanthids. If you look around the clownfish you will notice things floating through the water. This is part of the filtration process!

As tank inhabitants swim or crawl around and do their normal activities they are also moving detritus and other things around. Water flow will keep it suspended in the water. Then a filter picks up the suspended particles and catches it with filter floss. The filter floss will eventually be removed and replaced. This catches a lot of things before they break down in the tank. The rest that isnt caught will be broken down and then filtered by the live rock. The general guideline is to replace filter floss and filter socks every 3-5 days.

Hammer coral under slightly different light


Lighting is another hot topic for coral reef tank care. Coral and some inverts like clams and anemone require light for energy. If they do not get enough they will stretch up taller and closer to the light. If they get to much they will either move, bail out, or bleach and die.

Coral also need specific wavelengths of light to grow properly. The ocean water is really quick to absorb light and color. By the time you reach a few inches deep, most of the water is filtered into blue lighting. This is what coral are most used to.

Coral prefer lighting in the 410-520 nanometers. They also have a small peak in the 620-680 nanometer range. The lower 400 range is the blue/violet/ultraviolet range while the 620 range is closer to red.

The two pictures above are of a hammer coral under different lighting. As you can see it changes how the coral look. Some people care about this more than others. A lot of reef tank lighting tend to have a "Windex effect" where everything is washed blue. Some people enjoy this, and the coral do not mind as long as they are getting the proper wavelength. But a lot of reef keepers are trying to get as much "pop" out of their coral as they can. They tune their lighting to bring out specific colors. This is often a mix of actinic lighting, heavy blue color, and enough white lighting to remove the windex effect.

A big part of lighting is also filtration. If the water is tinted and dirty then less light will penetrate through the tank. Look into putting ROX carbon in the filter to help combat this.

This content reflects the personal opinions of the author. It is accurate and true to the best of the author’s knowledge and should not be substituted for impartial fact or advice in legal, political, or personal matters.

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