How to Start a Reef Tank: The Tank

Choosing the tank size and dimensions is my favourite part of setting up a new tank! The possibilities and potential are endless! But choose carefully. Most of us want a tank full of colourful coral that covers the rock work. Going big on the tank means it will take longer for things to cover the rock work and it will cost more to fill, so careful planning and thought is needed.
When it comes to tank size, be prepared for the amount of work required to maintain and clean it. For example, a reasonably stocked 200 gallon tank would mean you need to mix and change 40 gallons of saltwater to do a 20% water change. That’s a lot of water to make and store, the average Brute container only holds around 15 gallons. In short, the bigger than tank, the more it’s going to cost to fill it, both with water and livestock.

A 40 gallon shallow rimless reef tank by Miracles Aquariums. 36″ x 18″ x 16.5″ LxWxH.


    • Aquascaping. Shallow tanks are easier to get your hands and arms into and require less intense lighting. This could save you on initial lighting cost and make placing new corals easier.
    • The tank stand. What you place the tank on must be strong enough to hold the tank, water, rocks, sand, lighting, powerheads etc. Plan for at least 10-12 lbs per gallon of aquarium. So a 40 gallon aquarium should be on a stand that will comfortably hold 400+ pounds.
    • Space for cleaners. Plan to leave some space around your rocks for magnetic glass cleaners/scrapers and fish to swim. Dirty glass can quickly spoil a beautiful view.
    • Think long term. Plan to run the tank for 5+ years before upgrading. This will help you decide on the most appropriate sized tank and set you up for success.
    • Location is also important. Try to place it out of direct sunlight, away from heating vents and if possible near a cold air return vent to allow humidity to escape.
    • Think about front-to-back depth. Tanks that are 14′-16″ deep will make aquascaping easier. With careful coral placement you can then create the allusion of depth. For example, a flowing hammer or leather coral in the back of the tank gives the viewer the impression that ‘there’s more back there’.


Longer tanks offer more space to hang equipment and hide heaters etc, if you decide not to run a sump setup. Standard tanks use much thinner glass than custom tanks and have black plastic top braces. Custom tanks can be rimless or eurobraced, and almost any glass thickness you could want. Talk to your custom tank builder about their recommendations on glass thickness relative to tank size. On custom tanks you also have the option of using low-iron glass that is much clearer than standard glass, which has a green tint the thicker it gets. Ultimately, pick something that fits your budget and that appeals to your tastes.