What should I test for in my aquarium?

When thinking about testing parameters in the aquarium, it can be a daunting thought. What should I test? When should I test it? Why am I testing this particular level? So many questions come to play when test kits get involved. I like to think of testing the aquarium in three aspects or compartments; testing while cycling a tank, testing as a preventive/knowledge aspect, and testing in search of a cure/ there is an existing issue.

As far as prevention testing goes it's not frowned upon to test as many levels as often as possible. However, there will be some key parameters to keep your eyes on so that you are not burning through test kits, as this can be pricey and time consuming.

When talking about testing for a cure or testing for an issue, this won’t always be a bad issue. For example, you may be adding more stony corals to your reef tank and will need to know the calcium consumption and intake of the heavier coral load. But then also too if you have an algae breakout or you are losing fish you will want to check certain levels as well.

What should I test during the cycle of my fish tank?

The three most important levels to check while cycling a tank are going to be ammonia, nitrite, and nitrate. When you begin a fish tank the introduction of a “bioload” into a closed loop system will begin the nitrogen cycle. This bioload (or fish) will poop once you feed them. Fish waste and uneaten/decaying food will be the leading cause of ammonia. For the first week or two, measuring ammonia levels will be imperative. Bacteria break ammonia down into nitrite. This inturn will need to be tested as well (you should still be testing ammonia to ensure its decline). Bacteria break down nitrite into nitrate and yes, you guessed it, by the end of the nitrogen cycle you should be testing for all three levels. Ensuring that ammonia and nitrite are 0 and nitrate is less than 20ppm (or as low as possible). Time for a water change! 

What should I be testing for all the time in my fish tank?

As mentioned above, it is always highly encouraged to monitor as many levels as possible. This is made easy these days with probes and digital readouts. But a lot of us are still manually testing our aquariums. And for this reason we don’t want to waste time and money on testing for a levels that we shouldn’t be as concerned about. One of the things you will want to track that will be true for every aquarium is nitrates. The reason for this is we are feeding our fish and they are digesting the food, turning it into waste. This will give us a good idea how often to do water changes, change pads, feed, etc. 

There will be some levels certain hobbyists should check more than others. This all depends on what type of system you’re running, what kind of water you’re using and what kind of nutrient input there is. One example may be hardness. If you are on well water or don’t know the hardness of the water you may be testing the hardness more often than not. Another example would be calcium in a reef tank. You would want your calcium levels to be around 400 to 450. And this may be easy to maintain in the beginning but as you add more and more corals the calcium, magnesium and other trace element consumption grows larger and larger. Lastly you may be facing an algae break out. In this case you may be testing phosphate levels.

So what levels should an aquarist be testing consistently on a regular basis? I would say that after a tank is established the only thing to really keep your eye on is PH and nitrate levels. But as time goes on and things change in the aquarium you will be posed with different questions and the best way to answer them is with numbers from testing.

When should I test PH in my fish tank?

PH stands for the power of hydrogen. PH is essential to the health of your aquatic animals. A pH that is too high is considered alkaline and pH that is too low is considered acidic. Different fish require different pH levels. PH is measured on a scale 1 to 14. 7 being neutral. 

There is no right answer for the question: What should my pH be at? This will all depend on the type of animals you have in your aquarium. For example tropical fish will take a PH close to neutral at about 7.0. Goldfish will like about 7.5. A lot of cichlids will take it slightly higher at around 7.7 to 8.0. And in the Marine world it is generally kept at 8.2. There are also many tropical fish that like pH around 5.5 to 6.8. So to get to the bottom line, know what your fish requires, test for it, and accomplish it. 

If water is too acidic or alkaline your fish can be prone to disease. The biological make up of fish depends highly on the pH of the water chemistry. PH changes are very hard on your fish. They can either highly stress them out or even kill them. It’s similar to oxygen for us. If oxygen becomes depleted we struggle to survive. We can be prone to severe brain damage or even death. When there is an extreme pH fluctuation within an aquarium this can be traumatic on the aquatic animals.

To test pH there are a variety of kits out there. Any of them would be fine. It is always suggested to research the product before you buy it. For freshwater aquariums I have personally used a variety of kits. Any of them would be fine. It is always suggested to research the product before you buy it. For freshwater aquariums I have personally used API test kits and for saltwater aquariums either automated pH probes or PI test kits and for saltwater aquariums either automated pH probes or manual Salifert kits. There are also manual digital kits available on the market that claim utter accuracy. 

To alter the pH in your aquarium you should always focus on the source of the water. If you are using a reverse osmosis system for a saltwater aquarium then you’ll begin with a relatively neutral pH. When adding salt to it you are then buffing up the pH from around 7 to 8.2. In the freshwater world your source water will be your tap. If your tap as well water your pH may be slightly high and packed full of minerals. If you are using city or reservoir water your pH may be closer to neutral, sitting at around 7.4 to 7.8. But this of course is different depending on where in the world you are. To alter pH and either fresh or saltwater there are different over-the-counter buffers you can buy that work just fine. There are also different types of rock that will raise or lower your pH. Be sure when adding anything natural to the aquarium research it before you put it in.

When should I test nitrates in my aquarium?

The chemical formula for nitrate is NO3. Nitrates are a salt of nitric acid made up of one nitrogen atom and three oxygen atoms.

Nitrates should be monitored often in the home aquarium. Whether it’s a fresh or saltwater tank, you have live animals in there that eat and poop. Beneficial bacteria or nitrifying bacteria break down the waste into what’s known as nitrates. At high levels this can be very harmful to your tank and inhabitants. So to answer the question quite directly it is recommended to test nitrates as often as possible. Every day would be ideal however this would become very time consuming and a bit costly. A few times a week should suffice especially if you have a heavy nutrient input (if the tank is fed a lot). At low levels nitrates are not harmful to fish. As a matter of fact some plants and animals rely on them. But at higher levels depending on what you are running in your system, nitrates. can be very harmful

In order to get your nitrates down, if they are very high, is to do a water change. If you feel like you’re constantly doing water change after water change and your nitrate levels are staying high you may need to look into other aspects or variables of your aquarium. What kind of filtration do you have on it? Are you running carbon? How often are you feeding the tank? When you feed the tank are the fish consuming all of the food? Cutting back on feeding and upping your filtration game is a good way to export nitrates as well.

When should I test for phosphate in my fish tank?

The chemical formula for phosphate is PO4. Phosphate is a chemical compound that is made up of one phosphorus atom and four oxygen atoms.

You should test for phosphate at least weekly or biweekly in a reef aquarium. Phosphate compounds can take the place of calcium carbonate molecules when coral is attempting to build a skeleton and grow. Phosphate levels at 0.04ppm and higher can hinder the growth of coral and promote algae growth immensely in your aquarium. A good telltale sign of one to test for phosphate is also when you see excessive algae growth in your fish tank. 

Some simple and easy ways to lower your phosphate levels would be as follows. First and foremost water changes are very important. Being on top of your maintenance schedule is essential when trying to lower phosphate levels. It is also recommended to have a well working and tuned protein skimmer working on your aquarium. Growing macroalgae in a refugium can help lower phosphate levels as well. Whether it be Caulerpa or Chaetomorpha, once it grows and absorbs phosphate it can be removed.  A percentage of macroalgae in the sump can be thrown out. And you may leave the rest to grow and absorb more phosphates out of the water column. This acts as a way of phosphate and nutrient removal.

When should I test for calcium in my reef tank?

The abbreviation for calcium is Ca on the periodic table. Calcium is a chemical element.

Calcium can be tested soon after you have successfully cycled your reef aquarium. Certain commercial salts will have calcium and other trace elements in them. Natural sea water is typically found to be around 400ppm when measuring calcium. This of course is dependent on where in the world you are testing and at what depth. 

Before testing calcium carbonate in your home aquarium you will want to ask why you are testing for this. If you are running a “fish only” system or a soft coral system this will not be so pertinent to test for as the trace elements found in salt mix will suffice. If however the system has large polyp stony coral and/or small polyp stony coral, you may want to evaluate what the calcium levels are in the tank. In order to accomplish raising and maintaining calcium levels there are a few methods you can choose to execute. As a beginner to moderate level you can begin dosing “two-part” which is made of calcium and alkalinity, typically sold in two separate bottles. Next as a moderate solution you may introduce Kalkwasser. This is typically combined with an auto top off system or dosed directly into the aquarium. Finally as a more “expert” level you can look into a calcium reactor. It is important to note that none of these should be done in conjunction with each other. One method should be chosen and implemented.  

When should I test for alkalinity in my reef aquarium?

Alkalinity is the yang to the calcium yang. Alkalinity should be kept at around 8-9. The symbol or abbreviation for alkalinity is dKH. This stands for “degree of carbonate hardness”.

Alkalinity is important for our marine animals and coral because they will “use up” alkalinity over time. Having said that it will be tempting to dose for dKH but you won’t know what to dose without testing first! This goes for all levels in the aquarium, check and recheck before you dose!

To alter the alkalinity (as mentioned above) you will need to implement a two part supplement. You may accomplish this by dosing two part (1&2 or A&B) or dosing Kalkwasser through an ATO system or maintaining calcium and alkalinity with a reactor. These are the three most common and effective ways to maintain calcium and alkalinity levels. And again, you will choose ONE scenario - NOT two of or all three. 

When should I test for magnesium in my reef tank?

Having set calcium and alkalinity, it is recommended to test and maintain the appropriate magnesium level. The abbreviation for magnesium is Mg. This element is the balance beam for which calcium and alkalinity sit on. The general magnesium level in seawater is just under 1300 ppm. 

The reason for testing magnesium in your reef aquarium is that first and foremost it is essential for coral health. Although it does not deplete like calcium it is vital to the building and structure of the coral invertebrates in your aquarium. Think of Mg as the “third” component of your two-part dosing schedule. Magnesium will be the center bearing for which some of the essential elements will rest upon. In that respect Mg has been under-rated in the reef keeping hobby. 

As always prior to dosing the aquarium with magnesium, you should always test for it to see what level your tank sits at. Some commercial salts will have a certain level of magnesium in it. This will naturally replenish magnesium as water changes and topping off is performed. But if you have tested and find your magnesium is low, a good way to raise and maintain it is to dose. When dosing Mg you should always test as you go. What is meant by this is to periodically test while levels are being increased. As mentioned above, magnesium does not deplete as quickly as other compounds. Having said that, it should be monitored. It is also good practice to test and monitor calcium and alkalinity levels in conjunction with magnesium levels. Although Ca, dKH and Mg are all maintained at optimum levels, stability is still the key! When testing and dosing it is important to remember that “chasing numbers” is never ideal. For example if you shoot for 1300ppm Mg and your test reads 1220ppm yet you have a show stopping tank, leave it alone and enjoy. Don’t chase numbers! Shoot for stability and consistency.