Aquarium Water Testing Made Easy: 9 Handy Water Parameters

Photo by Zengame (Flickr)

Just like water changes, aquarium water testing should be part of your regular routine.

Most goldfish tanks should be tested at least once per week (or more frequently within the first months of setting up a new aquarium) and when you notice goldfish disease symptoms.

Aquarium test kits are absolutely vital for monitoring and keeping water parameters in your tank under control. By testing the water weekly, you’ll discover potential disasters before your goldfish’s lives are on the line.

You probably already discovered dozens of freshwater test kits on the market – each testing for completely different things!

So which water parameters should you test?

Vital Tests First: 4 Aquarium Water Testing Kits You Can’t Do Without

Some aquarium water testing kits need to be used weekly to keep your tank water healthy and clean – ammonia, nitrite, nitrate, and pH are in the front of the line.

It doesn’t matter if your tank is just getting established or you’re in the sixth year running. If ammonia and nitrite run rampant in your aquarium, it could spell disaster for your goldfish!

Just getting the nitrogen cycle started? You can watch the stages unfold by testing for ammonia, nitrite, and nitrate. You may also want to test for pH, since pH can have a direct impact on how harmful ammonia is (and drastic pH changes can kill your goldfish!).

Let’s talk water parameters. We’ll take a quick dive into what each parameter is, how it impacts water quality, the best test kit to use, and why aquarium water testing should help.

1. Ammonia

Ammonia is produced when uneaten food and waste break down.

To beneficial bacteria, ammonia makes a delicious feast! But if the nitrogen cycle hasn’t completed (or something kills off all your good bacteria), ammonia can cause serious damage. Prevent problems with an aquarium water testing kit.

• Always keep ammonia at 0ppm (parts per million). Just getting your tank started? Sometimes small traces are inevitable (keep ammonia at 0.06ppm until the nitrogen cycle runs its course).
• Change the water immediately if ammonia is found in an established tank. Find the source. Ammonia is common in overcrowded tanks or when goldfish are overfed, especially when the biological filter can’t keep up.
• Ammonia can be tested weekly with an API Ammonia Test Kit (liquid reagent) or master test kit.

In an established tank, ammonia should never be a problem.

2. Nitrite

Nitrite is developed when beneficial bacteria break down ammonia.

Usually your biological filter will convert nitrite into nitrate before it’s a problem. But if ammonia gets out of hand, nitrite may soon follow.

• Keep nitrite at 0ppm (or below 0.75ppm if starting the nitrogen cycle).
• If nitrite levels increase over 0.75ppm, perform an immediate water change and boost aeration. Often, high nitrite levels can mean there’s a serious problem with ammonia (and the biological filtration in your aquarium).
• Test nitrite weekly, either with an API Nitrite Test Kit or master aquarium water testing kit.

While nitrite is only slightly less harmful than ammonia, it is still very toxic (and fatal) to goldfish.

3. Nitrate

Created when nitrite is broken down in the last stage of the nitrogen cycle, nitrate doesn’t harm goldfish unless levels are high.

Struggling with algae? Large traces of nitrate can attract this pretty common, yet very vexing plant, leading to unpleasant algal blooms.

• Keep nitrate levels below 40ppm (5 to 20ppm is ideal).
• If nitrate levels are high, perform a partial water change. Nitrate shouldn’t be a problem if you keep up with tank maintenance and aquarium water testing.
• Test nitrate weekly, either with an API Nitrate Test Kit or master test kit.

Nitrate should never be a problem if you’re performing regular water changes.

4. pH

pH measures how acidic or alkaline (basic) your aquarium water is, on a scale of 0 to 14.

The lower the reading, the more acidic your water is. When pH levels hit 6.5, the beneficial bacteria that keep ammonia under control start having trouble and the nitrogen cycle stops altogether at a pH of 6.0 and below (source) – this can cause dangerous ammonia spikes!

Likewise, the higher the reading, the more alkaline the water is. Ammonia is actually more toxic to goldfish when pH is high (source), while nitrite is more toxic at lower (acidic) pH levels (source). Also not good.

A reading of 7 is always neutral, and water hardness can affect pH.

• Goldfish love alkaline water and prefer a pH of 7.2 to 7.6. Though, even if the pH is close to this range (but not quite there), your goldfish should still do well.
• You should only change extreme pH readings and only do so in very small increments (drastic changes can kill goldfish). Use a product like PH Up or PH Down to raise or lower pH.
• Keep pH levels constant (and avoid changing it unless absolutely necessary). Test for pH weekly or if ammonia or nitrite become a problem, either with an API PH Test Kit or master test kit.

Instead of buying each test separately, you can save a little money and purchase a freshwater master test kit that includes tests for all four water parameters in one box.

Aquarium water testing kits can be purchased anywhere tank equipment is sold. You can also let your local pet store analyze a portion of your aquarium water. Watch out, though. Depending on the shop, there might be a small fee.

Keep test kits handy and you can ensure that water parameters never fall below the safe range. By maintaining top-quality water with aquarium water testing, your goldfish will thank you with vibrant colors and happy, long lives.

5 Useful Water Parameters Every Aquarist Should Consider

You can test for just about any imaginable water parameter in your aquarium.

Photo by Yuko (Flickr)

Master freshwater test kits give you everything you need to test well-known water parameters like pH, ammonia, nitrite, and nitrate. But while these four are the most important, you shouldn’t brush aside other helpful parameters as well.

When aquarium water testing, the following water parameters can help.

1. Copper

Copper is generally only a problem when using copper-based medications to kill off parasites (like white spot disease). Sometimes you may also notice copper in your tap water.

It helps to keep track of copper concentrations when treating parasite diseases. Aquarium water testing lets you know when copper-based medications are effective or if you should stop treatment (if copper gets out of hand).

• 1.5 to 2ppm of chelated copper sulfate (used in Mardel CopperSafe) is often recommended for treatment (source). When using any copper-based medication, follow the directions on the bottle.
• Test copper levels (0 to 4ppm) with an API Copper Test Kit.

Some invertebrates are very sensitive to copper and high traces of it are lethal to goldfish. Be careful to only use the correct dosage during any treatment with medication.

2. Chlorine

Chlorine in untreated tap water can be a huge problem – especially for goldfish! Luckily, there are many products (water conditioners) you can use to remove it. Learn more about how water conditioners work in this tap water conditioner guide.

If chlorine makes you nervous, you can test your conditioned tap water for chlorine before pouring it into your aquarium. But testing for chlorine won’t be necessary if you’re using a good water conditioner.

• There should be no chlorine in aquarium water.
• Tetra EasyStrips has a chlorine test built in (also tests nitrite, nitrate, GH, KH, and pH).

If chlorine is found in your aquarium water, it can literally kill your goldfish overnight! Always treat tap water with a water conditioner.

3. General Hardness (GH)

General hardness lets you know how hard or soft your aquarium water is.

The more dissolved minerals (like calcium and magnesium), the harder the water is. Low traces of dissolved minerals indicate that the aquarium water is soft.

• While goldfish do fine in both hard and soft water, 200 to 400ppm might be ideal.
• You can test both general hardness and carbonate hardness with an aquarium water testing kit.

4. Carbonate Hardness (KH)

Carbonate hardness helps keep the pH in your aquarium stable.

The lower the KH, the more pH can change (pH crashes are dangerous!). Increasing the carbonate hardness can prevent pH shifts.

• Raise KH when pH shifts become a problem, but don’t raise it too high. Water with a high KH (200ppm or more) may have high pH levels (source).
• Test carbonate hardness and general hardness with an aquarium water testing kit.

5. Phosphate

When wastes break down, phosphates are released into the water. While phosphate won’t hurt your goldfish, too much of it can cause unsightly algae growth.

• If algal blooms are an issue, testing phosphate might pinpoint the problem. The lower the phosphate, the better (in an unplanted tank). In planted aquariums, you may want to have a nitrate/phosphate ratio of 10:1.
• Test phosphate levels, from 0 to 10ppm, with an API Phosphate Test Kit.

Raising goldfish is a big responsibility. After all, their lives depend on your care!

While it may be easy to get caught up in things like aquarium size, shiny pebbled substrate, and vibrant foliage, you should never overlook water quality.

Crystal-clear water will trick you.

It’s impossible to tell whether the water is healthy for your goldfish unless you regularly test the water. You don’t have to test every water parameter listed above, but you should make aquarium water testing a habit (at the very minimum, test for ammonia, nitrite, and nitrate).

Which Water Parameters Do You Test?

Do you test for certain water parameters? Has it helped you prevent infections?

Share your aquarium water testing experiences by submitting a comment below!