Is that water?… Good?

Take a look at this picture with bottles of water. Without their labels, you may be forgiven for thinking that they’re all the same – just plain water. But their labels give away their water chemistry. From left to right, they are: unbuffered soft water; plain water; hard water; water that is supersaturated with carbon dioxide; and acidic water.

But, what about the water you rear your fish in? They certainly don’t come with labels. How do you know if the water is suitable (or if it’s still suitable) for your fish? Why test?

Elevated ammonia, elevated nitrite, low pH, elevated temperature and low dissolved oxygen are killers of fish. Nitrates can accumulate and lead to immunosuppression. The list goes on.

Moreover water chemistry may change due to many factors. Some parameters vary depending on the time of the day, season, biomass, feed rate, water temperature and more. And the significance of some water parameters are influenced by other parameters (e.g. ammonia is more toxic at higher pH and temperature).

So, what parameters should we be testing regularly? For freshwater systems, we recommend testing regularly for ammonia, nitrite, nitrate, pH, KH, GH, water temperature, salinity and dissolved oxygen. For planted tanks, include carbon dioxide. For marine tanks, include phosphate, magnesium and calcium.

Watch this video for an example of how you can test your water –

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Yours sincerely,

Dr Richmond Loh
DipProjMgt, BSc, BVMS, MPh (Pathology), MANZCVS (Aquatics & Pathobiology), CertAqV, CMAVA, NATA Signatory.
Aquatic Veterinarian & Veterinary Pathologist
THE FISH VET, Perth, Western Australia, AUSTRALIA.
Mobile Aquatic Veterinary Medical & Diagnostic Services.
Ph: +61 (0)421 822 383
Skype: thefishvet

President WAVMA 2014


One thought on “Is that water?… Good?

  1. If you are saving water to be tested DO NOT use such bottles! They are unlabeled– no traceability. The original contents may still be affecting the water test results. If preservatives have been put in the bottles (or if the are just filled with tank water) some one may drink the contents and get sick. Always use commercially pre cleaned bottles marketed for water sampling. You back bench “lab” can not properly clean previously used bottles especially if trace contents such as pesticides are to be tested.


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