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The Jar Test

21st Nov 2019

So what the hell is The Jar Test I hear you cry? Well, basically it’s a simple but effective way to diagnose what may be causing cloudy, murky or green water issues in your pond. Once you’ve diagnosed the cause of the issue it should be a simple matter to find the solution.

The Jar Test is pretty easy to carry out. Just dunk an empty, clean, clear jar in your pond and let it fill with your pond water. Next leave it for 24 hours. This should let everything settle, and basically overnight your jar will have become a miniature snapshot of your pond’s ecosystem.

All you need to do now, is to ‘read your jar.’

Green Water

If your jar is showing mostly green tinged water or has green particles floating in it, you most likely have a bit of an algae problem. Suspended algae, are a microscopic single celled species which can form into ‘blooms’ and give your pond water a green ‘pea soup’ appearance. In this instance the jar test is telling you to treat for green water and algae. There are various water treatment products that can help you deal with your green water/algae problem.

Tea-Coloured Water

Sometimes The Jar Test will result in discoloured murky water with a brown tinge to it – it may in fact resemble a tea like colour. This indicates that you have organic debris decomposing in your pond. This can be particles from dead leaves, twigs and other plant debris that are breaking down and mixing into the water column and discolouring it. This process produces tannins, which means that believe it or not in the more severe cases your pond is actually like a big teacup, with debris at the bottom, and floating in the water - acting like tea bags.

If you have this problem then the first thing to try is to pysically get rid of the organic matter. You can do this by removing any floating debris as much as possible with pond nets or similar tools. Next it's a good idea to vacuum out your pond with a pond vacuum. As the leaves, twigs, fish waste and other organic material decompose they produce a sludge like material at the bottom of your pond. A decent pond vac will help you get rid of this troublesome sludge.

Water with Sediment

If the results of your Jar Test show sediment resting at the bottom of the jar with clear water towards the top, then this means that you have a more serious case of rotting organic matter in your pond. There is most likely a sludge at the pond bottom and floating decomposing matter that is constantly being stirred up by your fish. If this is the case then we recommend a 4 step solution:

  1. Remove large debris. As mentioned earlier this can be done by use of pond nets and pond vacuums.
  2. Perform a partial water change
  3. Add a water conditioner to make the water safe for your fish
  4. Top up the beneficial bacteria

Follow this simple guide and The Jar Test should help you diagnose and deal with your issues, getting you back to healthy clear water, and happy fish in no time at all.