Maintaining proper water parameters in any type of marine aquarium is essential for the health of your fish, corals and invertebrates.
This is a quick guide to the parameters you need to manage for the common marine aquarium and reef tank set ups. Always research animals and buy from a supplier you can trust for good information, there may be special or unusual requirements for certain species.
Fish only system
A fish only system, often referred to as a FOWLR system is basically what it says on the tin, a marine tank set up for fish only without any corals and often without any inverts too. FOWLR is an acronym for 'Fish Only With Live Rock', however with the development of many successful man-made substitutes for rock and filtration now being available, live rock is no longer an essential aspect of this system.
Ideal water conditions for 'Fish Only'
Temperature 24 to 26°C
Salinity 1.024 - 1.026
pH 7.9 to 8.3
Alkalinity 7 - 12 dKH
Ammonia 0 ppm (under 0.2 ppm for short periods can be tolerated)
Nitrite 0 ppm
Nitrate under 20 ppm
Phosphate under 0.04 ppm
Calcium 380 - 450 ppm
Magnesium 1200 - 1400 ppm
Some notes on 'Fish Only' water parameters: (1) Fish alone are comfortable in a lower salinty down to 1.020. (2) Levels of phosphate are less important than in a reef tank however high phosphate can lead to unsightly algae blooms (3) Alkalinity, calcium and magnesium are less important in fish only systems however will have an impact on pH which will have an impact on fish health and their immune systems. (4) High nitrate will an effect on overall fish health and their immune systems. It may also encourage unsighly algae and bacteria blooms.
Reef tank or Reef system
Reef tanks have a few other common names such as coral system, mixed reef or SPS system. These are all variations of a marine aquarium where alongside fish there are corals and / or invertebrates thus providing the biodiversity you would expect to find on a living reef, it is the creation of a more complete reef habitat.
For the most part different types of corals such as soft corals, LPS corals and SPS corals will thrive in the same water parameters, there are some parameters that reef keeps like to change slightly for better results but they're more optional than essential, we'll consider that a little bit more further on.
Temperature 24 to 26°C
Salinity 1.024 - 1.026
pH 7.9 to 8.3
Alkalinity 7 - 12 dKH
Ammonia 0 ppm (under 0.2 ppm for short periods can be tolerated)
Nitrite 0 ppm
Nitrate 1 - 10 ppm
Phosphate under 0.01 - 0.04 ppm
Calcium 380 - 450 ppm
Magnesium 1200 - 1400 ppm
Some notes on 'Reef Tank' water parameters: (1) In reef tanks stability is paramount, keep parameters stable and make changes slowly. (2) People running SPS dominant tanks sometimes run nutrients (nitrate and phosphate) at the lowest levels, this can be effective but should only be attempted by experienced reef keepers.
Remember stability is key and often more improtant than matching recommended water parameters exactly. Be consistant in what you do with maintenance and identify changes by making use of home water testing kits, ICP tests and your own observations, identifying changes before they become a problem will save you time, money and the loss of animals.
Then is all that's left to do is kick back and enjoy your very own slice of ocean.
