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Alternatives to Rock Wool in NFT Systems · Hydroponics Daily

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  Hello, welcome back to Hydroponics Daily. Today I'll be talking about alternatives
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  to rock wool in NFT hydroponic systems.
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  So rock wool, also known as mineral wool, was
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  originally developed in the construction industry as a
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  thermal and acoustic insulator and
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  it's normally treated with a hydrophobic outer layer
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  to prevent it from sucking up too much water and that's
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  what you put in your loft and keeps your home nice
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  and cozy also sprayed into your walls and things like that but
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  it was found it was able to hold lots of water and crucially also
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  lots of air and allow roots to develop through its
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  matrix of fibers so mineral wool is is
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  made into slabs or blocks and it
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  contains in a waterproof sheath and it's
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  commonly used in nft but there are a number of disadvantages is
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  associated with its use so plants grown
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  in nft can be prone to fungal disease the
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  medium is not really reusable like other
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  hydroponic media and poor quality.
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  Grow media can generate high ph values above the
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  optimum for plant growth so you need to be careful with that and so
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  you need to soak it before planting is ideally glass wool
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  is a similar product that is sometimes used as an alternative
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  grow media to mineral wool and uses silica
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  as a starter ingredient instead of limestone and basalt
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  that's used in mineral wool so it could be more expensive
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  but if you you're interested how to see if you've got a local supplier of glass
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  wool and look at that mineral wool is normally disposed of after one or two
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  cropping seasons so that's normally straight to landfill or in some very bad
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  situations it's just dumped and buried on site so that's not environmentally.
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  Acceptable and you go down in the south of spain you
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  see a lot of the polytunnel covers as well just buried into
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  what is environmentally sensitive areas as
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  well as a lot of interesting flora and fauna around so that's
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  not cool so in other countries around
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  the mediterranean sea they use low density
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  volcanic rock such as tufa or tuff that can be commonly used in nft and locally
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  sourced and so cheaper than mineral wool and very easy and then And I talked
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  in the past about how the US Army were the first to actually commercialize hydroponics
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  and use it at scale during the Second World War.
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  And there they used locally sourced inner grow media, such as volcanic rock.
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  So if you're on a volcanic island in the middle of the Pacific,
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  you could use that for hydroponic growth or desert sand as a medium for root growth.
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  And so they can all be used. and then man-made products quarried material the sort of stuff that's.
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  Blasted in a furnace there's an emerging field
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  of organic hydroponics so strictly speaking not
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  organic but you know synthetic free and free of
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  man-made materials as it were so they
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  don't use mineral wool or synthetic fertilizers or
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  pesticides and and cocoa fiber is normally what
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  they use but they can use sand tough again pumice
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  they're all organic growing media that are
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  suitable for hydroponic cultivation the beauty of
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  sand and pumice and turf is that they can be reused cleaned
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  and can be steam sterilized you can remove the roots
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  from them you can burn the roots off them as well because
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  you're not going to get sand to the point where it's it's
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  going to melt so i said that sand is going to be the next
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  growing medium i'm going to try my spring onions on because they're just not
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  loving cocoa so there are some disadvantages of cocoa it's not as environmentally
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  sound as some people might make out and that's because of the co2 released and
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  getting it to where it needs to get to but certainly causes less environmental contamination.
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  Perlite and expanded clay particles so clay granules and beads is an option
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  they can be reused and sterilized but vermiculite and perlite can break down
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  and release toxic aluminium ions at low pH and so it's not an ideal for hydroponics.
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  I've certainly seen aluminium toxicity in a lot of my plants where I've been
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  growing in just perlite.
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  The other disadvantage of perlite is that it's dusty and that silica dust can
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  get into your lungs and you can have a real problem.
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  So always make sure you use one of those fabulous COVID face masks during its use.
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  You should always use a face mask really when you are potting plants up and
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  using especially like bagged compost, anything with anything like that because
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  especially if it's wet because you can get.
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  Legionnaires or certainly farmers longer if it's if it's decomposing you
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  need to be really careful especially in australia where the grow bags get really
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  hot for a long period of time there's a lot of a lot of reports of legionnaires
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  in in hot countries from especially developed hot countries where they're buying
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  grow bags i suppose in the developing countries it's not really reported if
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  someone dies legionnaires it's hard to determine that isn't it really so,
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  expanded clay parts granules were very popular not
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  so much you don't see them in as many or as popular in those grow rooms as grow
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  shops as you used to and they're produced at very high temperatures and kilns
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  at 1200 degrees celsius and they have a crystalline structure that's very porous
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  it's low density and it can be used in nft production can also be used for house plants as well,
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  but more commonly the clay parts the
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  clay beads are used in ebb and flood hydroponics and
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  you need to be careful because they're not all made equally there
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  are some really high grade ones and there's some really low grade
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  ones some of them are like shattered some of them
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  are like pure balls go to your local grow
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  shop ask them what's the best one that they.
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  Sell and there are a number of different suppliers of those
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  so if you've got an ebb and flood system they'd be good to look at but
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  equally nft you could use them you would need
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  to make sure that your roots do get into the fertigation solution
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  because it's not going to be drawing up as much of the fertigation solution
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  as a rockwool one is the beauty of rockwool
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  is that it once you put some moisture at the bottom it.
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  Soaks through to the hole of the matrix whereas clay
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  beads that's not going to be the case so you need to make sure that that's
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  why it's better in ebb and flood systems because you don't
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  need to rely on that that wicking zeolite is
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  another volcanic rock that can be used it's got very large particles
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  and it can hold a significant amount of nutrients
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  and surface so it's known and
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  it's normally mixed with other non-organic media zeolite i
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  think is the same stuff that's in cat litter trays as well
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  very absorbent you can use polyurethane foam
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  as a grow media it's chemically inert it can
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  be steam sterilized but it's a man-made plastic
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  so there are problems at disposal and you know
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  issues around using virgin plastics for
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  growing plants polystyrene beads the same
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  can be used in a similar way to perlite but are
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  much more durable than the mineral wool can be
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  reused and sterilized chemically inert not
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  broken down by extremes of ph so probably more robust than than rockwool polyester
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  fleece is used in microgreens and so you get a lot of wool as well in microgreens
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  and nft systems so and recycled fibers recycled.
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  Textiles very common now in in where you
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  don't need much grown media where you just want to have a very young plant and
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  harvest it so leafy greens recycled textiles are very popular the problem is
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  is that they can't be recycled again so it's almost like it's yes it's using
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  someone's green washed and said all our plastics all our textiles are recycled
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  but they go into this matting,
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  leafy greens are grown on them maybe once or twice and then
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  they're just landfilled so you need to be careful on that but
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  they're certainly an option for small plants you couldn't grow a very
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  large plant on a on a on mat just capillary matting unless that was the base
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  through which the fertigation solution dripped and then you had like potted
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  plants on top of it so capillary matting is used in ornamental nurseries to
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  deliver fertigation solution and also to mop up any runoff and allow plants
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  to just soak back a bit more.
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  If they've dried out a bit too much during the day where they've got a lot of evapotranspiration.
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  Shredded rubber tyres have been tested as a potential growing media in hydroponics
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  because tyres are a problematic waste.
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  But unfortunately, the results weren't great. And I've certainly not seen anyone
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  shredding tyres and selling that as growing media.
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  If you could, it would be very good because you'd have people paying you to
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  take the tyres and then you'd have people paying you for the growing media.
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  So that would be a win-win but unfortunately not at
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  the moment and there's a lot of contaminants a lot of
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  you know think of the chemicals that go into making a tire yeah the
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  vulcanization of all that rubber and things like that i don't think would
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  be great for your health there'd probably be a long-term health
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  risk especially if you had extremes of ph and all
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  of those ones above they can be blended and you could
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  mix and match various ratios that's the beauty of hydroponics
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  you can make your own bespoke mix you know just like
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  my sons do with their breakfast cereals and you
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  could have say a bit of matting at
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  the bottom you could have some expanded clay particles with polystyrene bits
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  or cocoa 60 40 isn't that 60 40 yeah that's 60 cocoa beads 40 cocoa and that's
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  that was invented for hydroponics not so much nft more just standard overhead
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  irrigation fertigation.
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  Or passive systems like autopot systems and that's
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  a very very lightweight and airy grow
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  media so that's a good hybrid mix but
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  there's plenty there's plenty of options if you if you've
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  got a local source of one of those things that i've mentioned it might be a
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  way to cut down on your cost cut down your grow media grow media
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  prices are crazy high at the moment especially for for a bag to grow media and
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  for rockwool and things like that so the more the price goes up the more people
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  will be looking for alternatives so that's been hydroponics daily for today
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  alternatives to rockwool and mineral wool for nft systems particularly thank
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  you very much for listening goodbye.