What you need to know about using test kits


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Nathan Hill explains how you can avoid some costly errors when undertaking this very important part of your fishkeeping routine.

Test kits are the most important part of the fishkeeping schedule. They let us know exactly what’s going on with our water and save countless fish lives.

However, many hobbyists make a few simple errors when performing tests and these can affect both our wellbeing and that of our fish.

Safety first

Test kits often contain hazardous chemicals. Check to see if your labels include a skull and crossbones, or even a raised triangle warning logo

You should always wear gloves and eye protection when testing. Many retailers will glove and goggle up when doing a test, but ultimately should be doing it some distance from you!

Take care when shaking samples in tubes. Always ensure the lid is on before you start and never cap with your finger or thumb. Many hazardous chemicals permeate the skin and you don’t want them roaming your body.

Then there’s the tube itself. Handle test tubes firmly and gently, especially glass ones. They break easily and the last thing you want is a cut on a sharp edge laced with testing reagent.

Keep things clean

Inaccurate results can be caused by soiled test tubes. Rinse them between tests and clean and dry them before storage. Dried reagent from one test can play havoc on another, providing false readings when everything in the tank is fine.

Clean the lids or caps the same way, too. Many people wash tubes, yet leave lids filthy.

Fill properly

Most kits offer clear instructions for use, but some are vague. When filling a test tube to a line, you want to fill to something called the bottom of the meniscus. This is a curve in the surface of the water that you’ll notice in a confined space — like a test tube! When measuring a liquid, always measure from the bottom of this curve, not the top where the fluid stretches up the glass.

One-way water

When taking a sample from a tank, try to use a pipette or syringe. In absence of these, if you need to put the test tube into the tank itself, never to spill any water back into the aquarium. If you take too much, pour it into the sink. Any residue left in the tube could easily wash back into the tank and harm fish.

Hold bottles upright

Some test kit bottles will give a slightly different drop size if held at a 90° or 45° angle when used. Many kits are designed to use a full-sized droplet from a bottle held at 180°, so always ensure the bottle is totally upside down when counting out drops.

Check the date

Test kits start to oxidise from the moment they’re opened and then only have a finite lifespan.

Always check that tests are in date to start with and then find out how long the kit lasts once you’ve opened it.

Many will only be good for around six months after first use, so that two-year-old kit might be giving good readings in the tank only because it’s stale!

Finally, it’s important to shake all the bottles before use!

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