Pondwater quality test kits

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Last updated March 2018
Monitoring water quality is essential for fish keepers and interesting for water gardeners.

Why test pondwater quality?
Types of pondwater quality tests
Pros & cons of dry, liquid and dip tests for pondwater quality
What pondwater quality parameters can you test for?
How to choose a pondwater quality test kit
Maintenance of pondwater quality test kits
Ten top pondwater testing tips

Why test pondwater quality?

For fishkeepers in general, and especially for Koi keepers, the testing of your pond water is essential.

Val testing pond water

There are so many factors that can affect the wellbeing of Koi that you should be equipped to monitor water conditions regularly, and to check specific parameters if you suspect a problem. You should always test water before adding it to an established pond; and test new ponds to decide when it’s safe to add fish.

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Types of pondwater quality tests

There are a range of testing devices available from fish-keeping and water gardening suppliers such as Bradshaws Direct.

Most tests involve mixing pond water with the appropriate chemical reagent, to detect nitrite for instance, and produce a coloured result. You then either compare the colour with the chart provided, or use an electronic colorimeter that reads the colour for you.

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Pros and cons of dry, liquid and dip tests for pondwater quality.

So-called dry-tab test kits are widely available. They consist of a test tube or vial along with a chemical reagent in tablet form, packed individually in foil. Kept in its packaging the chemicals should remain in good condition for a couple of years. Tablets don’t always dissolve well, so often a special crusher is included. Powders are easier to dissolve, but more difficult to measure precisely and to handle without spillage.

Liquid reagents get around these problems, often providing a quicker result, but they have a shorter shelf life.

Alternatively for complete ease, there are test strips that you just dip into pond water. If you need to check pH frequently, then a digital dip meter could be more economic in the long run. And for koi keepers needing precise measurements of water quality, see the range at Koi Water Garden.

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What pondwater quality parameters can you test for?

Apart from pH, there are tests for ammonia, nitrate and nitrite, dissolved oxygen, chlorine, calcium, iron, copper, phosphate, alkalinity and salt.

Multi-purpose test kits for pH, ammonia, nitrate and nitrite, such as Blagdon’s Master Pondwater Test Kit, are commonly available anywhere that caters for pond keepers. For those wanting to keep an eye on nitrites in particular, there is also a Tetra nitrite test available.

However, for other parameters, you’ll need a Koi specialist such as East Riding Koi Co or Koi Water Garden.

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How to choose a pondwater quality test kit

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.

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Maintenance of pondwater quality test kits

Test kits should be stored somewhere cool, dry and dark to keep the chemicals in good condition and prevent discolouration of the colour chart.

Electric testers should also be stored as carefully. Be sure to store only clean and dry test tubes with the kit to prevent them becoming prematurely brittle and discoloured.

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10 top pondwater testing tips

  • Check availability of refill reagents before buying a kit.
  • Always look at the colour strips to see if you can distinguish between the colours or shades. If you’re colour blind ask someone else to test for you, or use a digital kit.
  • Rinse out the testing tube in pond water before filling it with water to test.
  • Match the colour of the tested water to the colour chart by holding the test tube in front of some white card alongside the colour strip, with the light source from the side.
  • Match colours in daylight.
  • Always rinse out test tubes immediately after use, and leave them to drain.
  • Keep a record of the date, time and result of each test.
  • Test pH at different times during the day and night to check that fluctuations are not too extreme for Koi to cope with. Generally the acceptable range is 7-9.
  • Some dangerous conditions can develop very quickly. Check frequently for ammonia and nitrite, which are toxic at very low levels. The toxicity level of ammonia depends on the pH and water temperature, so test for all of these at the same time.
  • If you break the tubes or they discolour, don’t panic. It’s possible to buy spares.

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