Last week, we covered the most important parameters in Water Quality for Reef Tanks (Part 1) and why they are important for maintaining a successful reef tank. This week we will cover when, how and why it is important to check these parameters. Testing of these water parameters and keeping them in range and stable in a reef tank is essential for coral health. Adding regular testing to your routine will help ensure that all parameters are where they need to be and alert you to any possible problems that may be beginning, before they potentially cause damage to your aquarium.
This week, we will go over the following:
- What should be tested on a regular basis
- How to test for them
- Why they should be tested, and
- What ranges they should be kept within
Click on a parameter below to learn more:
Calcium | Alkalinity | Magnesium | pH | Temperature | Salinity | Phosphate | Ammonia | Nitrite | Nitrate
Calcium
When & How Often to Test: Heavily stocked reef tanks with corals and invertebrates should be tested once a week. Testing should also be done if the growth of corals has slowed down.
How to Check: Test kit, digital monitor / controller or ICP water analysis
What are the Proper Levels for a Reef Tank: 400 – 450 ppm (parts per million)
Why is it Important to Test: Keeping the proper level of calcium is necessary for the growth of hard corals, clams and clean up crews in your reef. Growth of existing hard corals and/or the addition of new hard corals, which use calcium to build their skeletons, will usually increase calcium consumption. Therefore, regular testing will help determine how much additional calcium needs to be added.
Alkalinity
When & How Often to Test: Reef tanks heavily stocked with coral, especially sps corals, should be checked at least once a week – and ideally twice per week. Alkalinity should be checked at the same time each day, as alkalinity levels can naturally fluctuate throughout the day.
How to Check: Test kit, digital monitor / controller or ICP water analysis
What are the Proper Levels for a Reef Tank: 8-12 dkh
Why is it Important to Test: Proper and stable alkalinity levels prevent rapid changes in pH. A large and sudden change in alkalinity is the number one cause of rtn (rapid tissue necrosis) in a reef tank. It is the first parameter that should be checked when there are any signs of stress with hard corals.
Magnesium
When & How Often to Test: Once every two weeks. If calcium and alkalinity are out of balance, magnesium levels should also be checked.
How to Check: Test kit or ICP water analysis
What are the Proper Levels for a Reef Tank: 1250-1350 ppm
Why is it Important to Test: Although magnesium is not depleted as fast as calcium and alkalinity in a reef tank, it is still vital to keep the proper levels. Magnesium prevents precipitation of calcium carbonate and is also used to help build the skeleton of hard corals.
pH
When & How Often to Test: At least once a week, or more frequently if the tank is newer and not yet stable. pH tends to drop at night when the lights of the tank go out. Therefore, it is best to test around the same time each day, preferably after the lights have been on for at least an hour.
How to Check: Test kit, digital monitor / controller or in-tank monitor. In-tank monitor attaches to the inside of the aquarium and will change colors to show the current pH.
What are the Proper Levels for a Reef Tank: 8.0 – 8.4 (down to 7.8 at night)
Why is it Important to Test: In general, corals only thrive within the proper pH range. When pH falls out of this range or changes rapidly it puts stress on corals and can even lead to coral death. A stable pH is required for proper calcification of hard corals. A slightly high pH can cause precipitation of calcium carbonate. A slightly low ph can cause corals to build thinner skeletons.
Temperature
When & How Often to Check: Daily and with every water change. During a water change, check the replacement pre-mixed saltwater and make sure the temperature is at or very close to the tank temperature.
How to Check: Glass thermometer or digital monitor / controller
What are the Proper Levels for a Reef Tank: 75-78 degrees
Why is it Important to Check: Keeping a stable temperature within range prevents stress on corals. It also alerts you to possible heating or cooling equipment issues. Temperatures below the optimal range can cause slowed growth and bleaching and temperatures above the optimal range can cause coral bleaching and death.
Salinity
When & How Often to Test: Once a week and with every water change. During a water change, test both the tank water and the pre-mixed saltwater. If more evaporation is noticed, then salinity should also be checked.
How to Check: Refractometer, hydrometer, or digital monitor/controller
What are the Proper Levels for a Reef Tank: 1.024 – 1.026 sg (specific gravity) / 32 – 35 parts per thousand (ppt)
Why is it Important to Test: Since corals need a certain water-to-salt ratio to survive, it is important to make sure salinity does not creep outside of the proper range. Testing salinity between water changes will allow any adjustments needed with daily top-off water. Testing pre-mixed water will help match salinities between the tank and the freshly mixed saltwater.
Phosphate
When & How Often to Test: Once a week. Also, test if corals show any sign of stress or if undesirable algae begins to grow.
How to Check: Test kit, digital monitor / controller or ICP water analysis
What are the Proper Levels for a Reef Tank: 0.02 – 0.05 ppm
Why is it Important to Test: Phosphates cause the brown algae inside of a coral to multiply causing it to turn brown instead of it’s true colors. It also restricts the intake of calcium carbonate, which corals use to grow their skeletons. Phosphates are also the cause of unwanted algae, such as green hair algae, to grow throughout a reef tank. Regular testing will also help determine when GFO or other phosphate absorbing media is becoming spent and needs to be replaced.
Ammonia
When & How Often to Test: Ammonia is generally tested daily during the natural cycling process when a tank is first started until the test reads 0. Once the cycle is complete, testing at least once a month is recommended to make sure an aquarium can adequately maintain the bioload.
How to Check: Test kit, digital monitor / controller or in-tank monitor. In-tank monitor attaches to the inside of the aquarium and will change colors to show how much ammonia is present.
What are the Proper Levels for a Reef Tank: 0
Why is it Important to Test: Ammonia is the byproduct of organic waste breaking down in an aquarium. It is toxic to corals. It is generally seen when cycling an aquarium and should not be present after a tank has been properly cycled and has the proper amount of nitrifying bacteria to eliminate ammonia.
Nitrite
When & How Often to Test: During the cycling process of an aquarium, nitrites should be checked daily until tests read 0. Once the cycle is complete, testing at least once a month is recommended to make sure an aquarium can adequately maintain its bioload.
How to Check: Test kit or digital monitor / controller
What are the Proper Levels for a Reef Tank: Less than .02ppm (parts per million) or 20ppb (parts per billion)
Why is it Important to Test: Although not as toxic as ammonia, nitrites are still toxic to coral. It is the second step in the nitrogen cycle before being converted to the less toxic nitrate. It is important to make sure nitrite levels are within range, especially after adding new livestock, as high nitrate levels can signal that an aquarium can not properly handle its bioload.
Nitrate
When & How Often to Test: It is important to test for nitrates once a week to make sure they are in an acceptable range for a reef tank. Nitrates should also be checked at the first signs of coral stress or algae growth.
How to Check: Test kit, digital monitor / controller or ICP water analysis
What are the Proper Levels for a Reef Tank: 0.025 ppm – 5 ppm (parts per million)
Why is it Important to Test: Regular testing for nitrates will alert you to possible issues with your tanks bioload and ability to waste removal. Keeping lower levels will also help reduce the chance of unwanted algae. High nitrate levels can cause browning of coral tissue and reduced polyp extension. Extremely high nitrates can also cause coral death.
Summary
Make a routine of testing water parameters regularly. It is one of the best ways to catch a potential issue before it can cause catastrophic damage to a reef tank. Many reef tanks fail when one of these parameters fall out of range, causing a domino effect with one parameter throwing off another.
Maintaining a proper balance of many key elements that work in unison to build a corals structure will ensure that corals will continue to grow in a reef tank. Keeping this balance, as well as the proper range of nutrient levels will help keep corals healthy and colorful.
If you need a quick reference guide to water parameters, we’ve got you covered!
For your convenience, our team has created a Quick Reference: Understanding Water Parameters PDF. Feel free to download and/or print this guide for whenever you need it!
Have a question about one of our products or need further assistance with your reef tank? Give us a shout at ATI North America, we’d love to hear from you!