Be sure to choose a test that is sensitive enough to detect what you need to know. There's no point testing for a critically low or high level if the kit cannot identify this.

And when you're studying the details see if you can make sense of the instructions, and check how long it takes for the colour to develop. See if the colour chart has a clear range for ease of reading too. Also, look at the test tubes or vials to see if they're marked for simple measuring.

Some instruction leaflets include space for a pond-testing log, which does encourage you to get into the habit of making records. Some leaflets also give advice on frequency of testing, dangerous levels, and suggestions for overcoming these problems - a useful starting point for beginners in fish keeping.

The price of the kit is not all that you should consider. Check how many tests are included for your money, and how much it will cost to renew reagents. Sometimes a new kit is actually a better deal than buying the refills.

For those of you making frequent checks and needing more precise readings, digital kits using a colorimeter may work out more economical in the long run. Battery and mains devices are available.