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Filter Medium

On a whim, I decided to start collecting my old used water filter granules to try experimenting with it as a growing medium.

I know they can be recycled (though I don't know if the granules are reused) but I do not have anyone who offers a collecting service near by. As I do not drive due to epilepsy, wandering around trying to find somewhere isn't an optio either.

So after leaving them to dry, rather than just throw them away, I opened them up with a craft knife and collected the granules from within. Easily done I might add.

I've considered adding them to pot compost (indoor & outdoor), especially my orchids. Growing seedlings in it and using to improve drainage. Despite the fact it does drain very well, it remains moist for sometime. It's quite attractive too.  As I assume it is composed of activated charcoal (at least in part) I would imagine it does not cause any harm.

Does anyone have any experience of using this for growing plants or use it for anything else around the garden or home?


Best Wishes for a peaceful Christmas and New Year.




  • DovefromaboveDovefromabove Central Norfolk UKPosts: 81,441

    No idea about your water filter granules, but love your 'nom de plume'.  

    In the very rural Suffolk village where I grew up (in the late 50s/early 60s) there was an elderly chap who lived in a cottage with his wife and their dog Turpin.  He was known to all as Dibbler.  He and his wife were very kind and one day I had a nose bleed on the way to school and they took me in and looked after me and Dibbler lent me his clean cotton handkerchief (which of course Ma returned, washed and ironed).  Happy days image

    “I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh

  • Gary HobsonGary Hobson Posts: 1,892

    Some inert materials are used as growing media. Some of the biggest commercial tomato growers grow their plants in loft insulation. The plants are nourished simply by drip-feeding them with tomato feed.

    An interesting question is whether filter granules are inert. Presumably they are not inert - they are designed to be active and to remove any chemicals from the water. So they may remove any potential nourishment from the water.

  • I'm so pleased my 'nom de plume' brought back happy memories for you Dove. Gave me a smile to read your post. image

    I had similar thoughts about the inert nature of the granules Georg. My thoughts were that since the filters were exhausted, not new, and since my wife insists we 'get our money's worth' before we change them, that the activity level of the filter might be negligible. I have no way to confirm this other than knowing the ability to filter water does decrease and eventually reaches a point at which they are effectively useless. I also kno activated charcoal is not able to filter indefinitely. I do not know what the white substance in the filters is to be able to check.

    Therefore I was willing to assume that their nutrient sequestration would be minimal if not entirely nil. Of course this is one of the reasons I asked the question, to gain any insight that members might have into any such problems. image

    I hope other members may be able to shed further light on the matter.

    Thank you for your time gentlemen. A very merry christmas to you.



  • Alina WAlina W Posts: 1,445

    The thing that I'm curious about is what the effect of chemicals caught in the filter might be. I have to assume that some of the chemicals "filtered out" actually remain bound to the granules.

  • Hi Alina

    I think most of the 'impurities' will be tightly enough bound either physically or chemically so as not to leach out or not significantly so. After all they would be prety poor filters if the filtrate leaked out agian.

    As they have been used to filter drinking water they don't contain anything too nasty, mostly calcium and potassium salts I would imagine As they've come from a filter kettle they have also been subjected to hight temperatues on numerous occasions and so microorganisms should'nt be a problem.

    Though I would again be happy to learn more.

    Thanks for taking the trouble to reply.

    Best Wishes.


  • Gary HobsonGary Hobson Posts: 1,892

    The scientific way to answer this question is to perform an experiment.

    Grow some seedlings in the medium, and observe what happens.

  • Yep Georg I know, I'm a zoologist by training! image

    Actually, you could analyse a lot of things to gain an insight. However, I agree. Try it and see....

    So I am.

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