The 8 best Colorimeter Checkers to buy for freshwater aquariums

Published: 20 June 2023

You've established your tank, introduced your new fish and got your filtration system running perfectly – what next? Continued monitoring and maintenance is the key to keeping your freshwater aquarium balanced and healthy. Our collection of colorimeter Checkers covers everything you need to keep track of your tank water, test tap water and take action to rebalance your tank over time.

Read on now to learn all about the eight best colorimeter Checkers to test freshwater aquariums, from chlorine to silica:

What is a colorimeter Checker?

A colorimeter Checker is a handheld, single-button operation tester designed to make your life easier and testing more accurate. Our range of Checkers covers various functionalities and purposes, from aquarium to pool testing.

Investing in quality aquarium testers is an ideal choice over testing strips or chemical test kits to save you time and reduce the risk of inaccurate or hard-to-decipher results.

The 8 best colorimeter Checkers for your freshwater aquarium

Not sure which colorimeter Checkers to buy for your freshwater aquarium? Here are eight of the best freshwater aquarium testing options you may want to consider:

1. HI-770 Silica High Range Handheld Checker

The HI-770 Checker makes quickly testing for silica molecules within your aquarium water easy. Silica is integral for many plants and animals. Diatoms – a form of microalgae – extract silica from the water as a part of their natural cycle of CO2 consumption and oxygen release.

Measuring silica is a valuable way to understand whether you have the correct levels in your aquarium. Too high, and you may need to reduce silicate to avoid a brown, dust-like coating in your tank. Too low, and diatoms may not have the necessary resources to release valuable oxygen into the water.

2. HI-721 High Range Iron Handheld Checker

In planted tanks, iron is a vital component in chlorophyll production, allowing plants to create energy through light absorption. While iron supplements aren't always necessary, keeping iron levels in your tank between 0.5-1.0 ppm can be beneficial. The HI-721 allows you to accurately identify readings in your aquarium water to maintain optimal plant health.

Beyond providing plants with the resources they need, too much iron can be a problem for life in your aquarium. Iron toxicity in plants can lead to stunted growth. Tap water can also contain iron, though this is unlikely to be at levels harmful to fish. But it never hurts to test your water to ensure it's of the best possible composition for your freshwater fish.

3. HI-718 Iodine Handheld Checker

While iodine testers are more frequently used within complex marine reef tanks, a suitable iodine Checker such as the HI-718 is valuable for all aquariums. Tanks containing invertebrates, in particular, can benefit from maintaining certain low levels of iodine in the water, providing the aquarium inhabitants with the optimal environment for healthy growth.

For freshwater tanks, iodine is usually provided in the amounts needed through the food you feed your fish. However, it's still a good idea to consistently test your aquarium water for a wide range of potential chemicals to ensure no changes need to be made. Anything beyond low levels of iodine could be toxic to your fish, so gaining peace of mind is never a bad idea.

4. HI-747 Copper Low Range Handheld Checker

Copper is a powerful tool in controlling algae and fish parasites within freshwater aquariums. Much like other chemicals, it's crucial to stay within a safe concentration level to provide the most benefit without causing harm to your fish. Too much copper can damage gills and depress the immune system, while too little can lead to parasite treatments in diseased fish not doing their job as effectively.

Carefully monitoring copper with a copper aquarium tester like the HI-747 Checker ensures you maximise treatment while reducing the risk of potential health problems. Tap water that has run through copper piping may also have a concentration of copper, making it important to test your water thoroughly before introducing it to your freshwater aquarium.

5. HI-775 Freshwater Alkalinity Checker

Balanced water is best for your aquarium, and alkalinity helps you to achieve that balance as effectively as possible. While some freshwater fish may prefer acidic water, others prefer higher alkalinity. By buffering the water against the effects of acids produced by excrement and other environmental changes, alkalinity provides your fish with the consistency necessary to thrive.

Using a handheld alkalinity Checker, such as the HI-775, regularly can keep water alkalinity in check, allowing you to make any necessary changes to avoid significant pH differences. Combined with a pH meter, like the HI-98100, you can maintain a better balance to prevent significant changes in your tank, keeping your fish safe and sound.

6. HI-701 Free Chlorine Handheld Checker

Chlorine is commonly found in drinking water as a disinfectant. While humans can easily tolerate a low chlorine level, the same doesn't apply to the fish or plants in your freshwater aquarium. Even a slight increase in chlorine can cause chlorine toxicity, which is harmful and potentially deadly to your fish if you don't react quickly enough.

Using a free chlorine tester, such as the HI-701 Checker, provides instant information about the amount of chlorine in the water. This measurement is invaluable for tap water, as it can allow you to use the correct dechlorination method to neutralise your water before it is introduced to your tank, ensuring you aren't exposing your fish to harmful and dangerous chemicals.

7. HI-700 Ammonia Low Range Checker

Measuring the ammonia level in your freshwater tank with a device like the HI-700 Checker helps you to identify if your filter is working correctly. As a natural waste product of fish, ammonia must be cleaned from the water to avoid build-up to toxic levels that can become deadly over time. Checking ammonia regularly ensures your filtration system is doing everything it needs to, reducing that risk.

Ammonia can also be found in tap water in a form called chloramine. If you use a dechlorinator on tap water, ammonia may be left behind, leading to ammonia poisoning if that water is introduced to your tank. Checking your tap water for ammonia before you use it can ensure all chemicals are neutralised, protecting your fish and their habitat.

8. HI-717 High Range Phosphate Checker

Phosphate is an essential measurement for freshwater aquariums. As the natural result of waste breaking down in the water, from excrement to decayed plants, phosphate can lead to larger algae blooms. The bigger the blooms, the less oxygen is left in the tank, leading to poor environmental conditions and the potential suffocation of your fish.

The HI-717 provides an affordable middle ground between costly professional instrumentation and less-accurate chemical test kits, offering a simple-to-use option for swift, reliable readings. By carefully monitoring phosphates in the water, you can swiftly take action to reduce algae bloom and restore balance for happy, healthy fish.



Shop handheld Checkers for aquariums at Hanna Instruments UK

Our range of Checker colorimeters at Hanna Instruments covers everything you need to check for your freshwater aquarium.

Have plans to expand into a tropical tank, or are you considering a bioactive reef aquarium? We have everything you need to test your water and keep your fish healthy.

Browse our full range of handheld Checker HC colorimeters today, or contact our team to discuss your requirements.



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