Water Parameters
What is the Nitrogen Cycle?
The nitrogen cycle is how fish waste is processed in an aquarium.
Fish release waste in the from of ammonia, which is very toxic. "Good" bacteria consume ammonia and turn it into nitrite. Nitrite is still toxic so another type of good bacteria consume nitrite and turn it into nitrate. Nitrate is the end product and is not toxic until it builds up in large amounts.
What is "tank cycling"?
When you are first setting up a tank, you need to build up beneficial bacteria before adding livestock. While the bacteria colonies grow, your aquarium may show levels of ammonia and nitrite. Usually, consistent testing shows a spike in ammonia, followed by a spike in nitrite, and both decline as nitrate is produced. Eventually, the good bacteria colonies can consume the ammonia as it is produced so testing will show a reading of 0.
A tank is considered cycled when ammonia and nitrite are both 0.0 and there is a small amount of nitrate present. For freshwater this usually takes 2 days to 2 weeks. And for saltwater this takes 2 weeks to 2 months. There are a variety of concentrated bacterial products you can add to speed up the process.
How do you remove Nitrate from your aquarium?
The most effective way of removing nitrate is to do regular water changes. We recommend 10-25% of the water changed every 2 weeks. (Some tanks require weekly water changes, while some can go 8 weeks without water changes. Regular testing of your nitrate level can determine when it's time to change the water.)
What other water parameters should you test?
Here is a chart showing what parameters you should test for and recommended results. (You may click on any chart for a printable version.)
Why should you test those things?
Ammonia, Nitrite, Nitrate:
Both ammonia and nitrite are toxic, you’ll want to make sure you have no ammonia or nitrite; especially before adding new livestock. Testing all of these can also indicate if your tank is going through a bacteria cycle or at what stage your initial tank cycle is in. As nutrients and waste build up, testing your nitrate can help indicate when it’s time for a water change and/or when to add nutrients for coral or plants!
We recommend the API master kit for these!
For more precise nitrate readings, use the Salifert kit which provides closer intervals of measurements. And for low nutrient reef tanks, use the Hanna checker.
pH:
The pH is a measure of how acidic or alkaline your water is with 7.0 being neutral. Some chemicals and additives may affect pH, especially CO2 plant additives. Some livestock can survive in a wide range but most have a narrow pH tolerance. Refer to the test chart above for recommended pH levels.
We recommend testing with the API pH or high range pH kit and using the Seachem pH monitor for planted tanks with added CO2.
Phosphate:
Phosphate is a macronutrient like nitrate. Having too much phosphate leads to unwanted algae growth. Some phosphate is required for healthy plant growth and coral color.
There are several types of acceptable test kits including those from API and Salifert but the Hanna checker is most accurate and recommended for reef tanks.
Salinity:
For salt water tanks, salinity is one of the most important parameters to test. It is important to keep salinity consistent and within an acceptable range.
The best way to measure salinity is in specific gravity (SG), which measures the density of the water. Salt ions makes the water more dense which can be accurately measured by a refractometer or digital salinity checkers. We do not recommend hydrometers as many factors affect their precision.
The following are explained for reef tanks only. Let’s talk about coral necessities first:
Coral can be separated into 3 groups: soft corals, large polyp stony corals (LPS), and small polyp stony corals (SPS).
(For more info on coral requirements CLICK HERE )
LPS and SPS corals have a stony skeleton which is largely made of calcium carbonate that corals make themselves by combining carbonate and calcium ions.
Alkalinity:
Alkalinity is a measure of how well your water buffers acids. Basically, it’s how well your water can stabilize pH. It’s important to have a high enough alkalinity in any tank so that the pH of your tank does not drop too low at night and deprive your livestock of oxygen.
Total alkalinity is the same thing as carbonate hardness or (KH). As mentioned, carbonates are a large element in coral skeleton and will be consumed by stony corals as they grow. It’s important to keep alkalinity at an appropriate and stable level. Beneficial bacteria as well as invertebrates with shells like clams and snails also consume alkalinity.
We recommend testing with a titration test like those from Salifert or Red Sea, or using the Hanna checker.
Calcium:
The other major component of coral skeletons is calcium ions. Much easier to understand, you can measure the amount of calcium available for your corals and other invertebrates. It's important to keep calcium at appropriate and stable levels.
We recommend testing with a titration test like those from Salifert or Red Sea, or using the Hanna checker.
Magnesium:
Unlike alkalinity and calcium ions, magnesium ions are a little more complex to understand as they’re not directly consumed by the coral skeleton on a large scale. Basically, magnesium in your water allows calcium carbonate to stay available in the water for the coral skeleton.
Magnesium ions are very similar to calcium ions on a molecular level. This prevents calcium from precipitating, or becoming a solid, and therefore unavailable for coral use. Magnesium can bind to the small amounts of precipitating calcium carbonate and prevent more precipitation.
So, levels of magnesium directly affect the levels of alkalinity and calcium. Testing and adjusting magnesium first, before alkalinity and calcium, will provide more stable parameters.
Magnesium is also consumed by coralline algae. Coralline algae is important for reef biodiversity and to prevent nuisance algae. While coralline algae can still grow with lower magnesium levels, maintaining levels will steady growth and algae prevention.
We recommend testing with a titration test like those from Salifert or Red Sea.
How can you adjust parameters?
Ammonia, Nitrite, Nitrate:
Water changes can reduce the levels of these in your tank. However, if you have small amounts of ammonia (under 0.50) or small amounts of nitrite (under 1.0) then a water change is not recommended as some ammonia and nitrite are needed as “fuel” for the beneficial bacteria to build a population. Instead, add bottled bacteria like those from Dr. Tim’s or Fritz turbo start and avoid disrupting your biological filters and gravel.
Nitrate can be kept at adequate levels with consistent water changes and filter changes as part of regular tank maintenance.
pH:
pH can easily be adjusted with powdered buffers. Keep in mind, most buffers contain phosphate, which can cause excess algae growth.
Another way to lower pH is to use reverse osmosis deionized water (RODI). This purified water has no extra ions so keeps the pH around 6.0. Additionally, planted tanks can benefit from driftwood and planted soils that help keep pH low.
To buffer pH in saltwater tanks, alkalinity supplements can be added.
Phosphate:
Phosphate is a macronutrient and is introduced to the aquarium through food, fish waste, and plant or coral additives. For low fish stocked tanks with plants or heavily growing plants, many plant liquid fertilizers, root tabs, or plant soil can provide phosphate. For corals, many quality foods provide phosphate.
A more common issue is high phosphates. Make sure you don’t overfeed and prevent overstocking your tank to keep phosphates low. Water changes can help keep phosphates low, but may not be enough. There are phosphate removers like granular ferric oxide (GFO) that can be added into a reactor or simply placed in a mesh bag and added to a high flow area of the tank, like in the filter.
Salinity:
The salt level can be adjusted by adding more saltwater or removing saltwater and adding RODI freshwater. Salinity should never be adjusted too quickly and never add a dry salt mix directly to your tank.
The following are explained for reef tanks only. It is important to begin with and only use a high quality reef salt mix! (We sell premixed Tropic Marin Pro-reef and dry salt mixes.)
Dosing tips: Test your water before dosing Alk, Ca, or Mg supplements! For more steady and accurate dosing, consider adding a doser machine. Dose slowly and directly into an area of high flow and water volume. Dose magnesium first, then alkalinity, and finally calcium with at least 10mins between doses. Start small and adjust doses after retesting.
Alkalinity and Calcium:
There are a variety of 2 or 3 part additives which are all very similar in composition. The major difference is some brands are more concentrated.
The old school and less precise but more cost effective route is adding kalk mixed in limewater (kalkwasser).
For heavily growing corals and clams consuming lots of calcium, a calcium reactor can be used. This reactor uses CO2 to dissolve aragonite pieces and add calcium back into the water.
Magnesium:
Always test and dose magnesium supplements before alkalinity or calcium. This is explained above. Some brands offer magnesium supplements which are recommended for most tanks. Magnesium is consumed much more slowly than either calcium or magnesium. Some 2-part additives combine calcium and magnesium, but this may not maintain appropriate levels for most tanks.