What is the right size tank for a saltwater aquarium?

The general rule is the larger the better. With saltwater tanks, water chemistry is absolutely critical. If you have kept some of the trickier freshwater fish such as discus or chocolate gouramis successfully, you will have some idea of what it is like to constantly test water and add this or that to balance the water chemistry. The bigger a saltwater aquarium is, the easier it is to maintain the water chemistry at a stable level. Stability is essential for keeping saltwater fish. Although they are by nature more delicate than freshwater fish, the hardier ones (such as clownfish) will tolerate a comfortable range of water paramaters. They will not tolerate fluctuations.

When you take an extremely large tank - say four thousand litres or about a thousand gallons - and set it up as a reef system with a sump or refugium, it is possible to largely simulate a coral reef ecosystem. A tank of this size, particularly if running on a refugium (like a sump, but containing liverock but no invertebrates or fishes) will support a wide range of marine life, similar to the 'real thing'. Because most of what is found in nature is present, the water chemistry tends to stabilise and then balance itself. Provided that the filtration is adequate and mature and the system is stocked slowly, it does not need much maintenance beyond evaporation topups, feeding and occasional water changes.

Medium sized reef systems - large tanks that will still fit in the average home - are a little harder to maintain because it may not be possible to include the full spectrum of marine life. Any tank smaller than 20 gallons or 80 litres is considered a nano tank. Nano tanks are regarded as one of the most difficult aspects of marine fishkeeping. Because it is impossible for such a small system to behave as a complete ecosystem, it cannot balance itself. Therefore this becomes the aquarist's job. You have to constantly test and correct the water chemistry, and there is a lot of water changing involved.

Marine is an expensive hobby, much more so than freshwater because you simply cannot cut corners with cycling, stocking or feeding and expect to have anything left alive. The best advice I can give to anybody considering going into marine is to DO YOUR RESEARCH. After careful consideration, and learning a lot about it, I decided not to get a marine tank because I didn't have the resources. If you do decide to go into marine, choose the largest tank you can reasonably afford to maintain, that will fit in the house. 50 odd gallons is supposed to be the ideal size to start off with. Unlike freshwater, where it's often best to start small and work your way up, if you start with a small tank and have little experience you may be setting yourself up to fail. There is no 'right' size - I have seen stunning marine invert tanks less than five gallons - but the bigger the tank is the more likely you are to succeed.

First answer by LauraFrog. Last edit by LauraFrog. Contributor trust: 251 [recommend contributor]. Question popularity: 1 [recommend question]