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waste fish tank water

Hi, does any one know if the water I remove from my fish tank when I do a water change would help or hinder my fruit and vegetables ?


  • I know my husband used to use it on our Orchids and they rocketed - loved it. Must be good for plants that like filtered water ie a neutral pH image

  • I use my old tank water for all my non edible container plants esp' the hungry ones like bamboo and ferns. I would not use it on any edible plants as the chemical treatments used to break down heavy metals and chlorine as well as any medications  used will still be present. I would not like the idea of eating anything grown is fresh fish waste! All the best

  • FischFisch Posts: 1

    chlorine, heavy metals in fish tank water? that would be a fish tank without any living inside but ok i guess you studied hidrobiology. Well if you didn´t do any fish desease treatment cause most of them contain copper you can use it on any edible plant its jus like a very dilluted fertilizer. And if you have some fish from amazon region like neon etc. which prefer osmosis water which has very low level of carbonate in it its indeed excellent for orchids too. Over all fish tank water doesnt contain any substances as maybe peat or oakbark extract to make perfect ph for south american fish species or maybe NaCl if its a seawater aquarium-this water i wouldnt use for any plants who are not specialized in salty soil lol.

  • I have a hydroponic system in use in my greenhouse using commercial nutrients. I have heard of fish tanks being used for hydroponic growing, as plants filter out nutrients in fish waste from the water, returning clean water to the fish. I have not tried it myself but I am sure that online search and visits to aquatic/hydroponic sites near you would provide you with more precise information.

  • Thanks to all

  • Has any managed to grow water cress using hydroponics and if so how?


  • I think all the nutrients from the fish waste would do it good referring to the emptying of the tank.and cress use to be grown on blotting paper and water cress is grown on just water,clean water but I would imagine it would have to be running water.image

  • Water cress stalks stood in a small jar of fresh water will soon root,(change water regulary to keep up oxygen levels). When roots appear transfer to a hydroponic system, Bubbler or NFT systems, I have used both, and you will soon find you have an abundent crop. In my systems I use a Grow nutrient mixture and a pH 6.5.

    I have not tried saveing any, seed but it may be possible to grow from your own plants from saved seed.

    Good luck TJ.


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