Silica gel as hydro medium

BobCajun

BobCajun

Well-Known Member
I've noticed that you can get silica gel kitty litter fairly cheap, and it seems to me like it might make a good hydro growing medium. It's not even very heavy when dry. In theory it would be much like sand but lighter and with larger grains which are able to hold about 3.5% of their volume or 40% of their weight in water, without changing its shape and size at all. It's not like those expanding crystals. Whether plants can extract that water I don't know, probably. I'll do a little test in one small pot to see how it performs. In kitty litter form, it looks like about the same price per volume as perlite or vermiculite actually. It may even contribute silicon to the plants, though that's just a guess.
 
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I didn't waste any time. I transplanted one of my small seedlings into it. Cracked a little when water was added. Didn't seem to absorb a huge amount. Water left in the saucer didn't absorb, at least not right away, maybe later over time. I did notice that light could penetrate it due to its transparency, so I added a thin layer of perlite on the top.

I guess the blue granules have cobalt in them, to make them change color based on how much water is absorbed. Don't know if that could be available to the plants or not. Probably best to look for the regular colorless type though, or the orange kind which is non-toxic. Fortunately, the stuff I got has very few blue ones in it. I could pick most of them out, though too late for that one I just transplanted. Oddly, the bag says non-toxic. These ones don't even turn pink. Could just be cheap knockoff blue gel that's just dyed blue or something.
 
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BobCajun said:
I didn't waste any time. I transplanted one of my small seedlings into it. Cracked a little when water was added. Didn't seem to absorb a huge amount. Water left in the saucer didn't absorb, at least not right away, maybe later over time. I did notice that light could penetrate it due to its transparency, so I added a thin layer of perlite on the top.

I guess the blue granules have cobalt in them, to make them change color based on how much water is absorbed. Don't know if that could be available to the plants or not. Probably best to look for the regular colorless type though.
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now you got me thinking. I wonder if regular kitty litter would work. it's clay but it does absorb water well and holds its shape when wet. does not get soft
 
mauricem00 said:
now you got me thinking. I wonder if regular kitty litter would work. it's clay but it does absorb water well and holds its shape when wet. does not get soft
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No I wouldn't use clay kitty litter, at least unless you baked it into "pottery" first. Why? Because it's either sodium bentonite clay or calcium bentonite clay, and you may not be able to tell which. If it's sodium bentonite it can be toxic to plants. Calcium bentonite would probably be good though. Maybe what you're talking about IS baked, since you said it holds its shape. I tried some once and it just turned into clay putty when wet, and seemed to poison my plants too. Apparently I got the worst kind.

Now about the blue kitty gel, I found good news. As I guessed, it's not really cobalt but just a dye. Somebody posted this in a comment "the blue in litter is NOT Cobalt Chloride… it’s food coloring. It would otherwise turn pink or orange when urinated upon, not the “yellow and blue make green, piss is easy!” source
 
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BobCajun said:
No I wouldn't use clay kitty litter, at least unless you baked it into "pottery" first. Why? Because it's either sodium bentonite clay or calcium bentonite clay, and you may not be able to tell which. If it's sodium bentonite it can be toxic to plants. Calcium bentonite would probably be good though. Maybe what you're talking about IS baked, since you said it holds its shape. I tried some once and it just turned into clay putty when wet, and seemed to poison my plants too. Apparently I got the worst kind.

Now about the blue kitty gel, I found good news. As I guessed, it's not really cobalt but just a dye. Somebody posted this in a comment "the blue in litter is NOT Cobalt Chloride… it’s food coloring. It would otherwise turn pink or orange when urinated upon, not the “yellow and blue make green, piss is easy!” source
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well it's worth a try. always fun to experiment. some ideals work others don't. but in addition to getting me off prescription drugs this is a fun hobby
 
mauricem00 said:
well it's worth a try. always fun to experiment. some ideals work others don't. but in addition to getting me off prescription drugs this is a fun hobby
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What brand is it? I'll see if I can find out what it is. If you had baked clay kitty litter it would work well, I would think. If it's not baked then it's just going to turn to putty.

I have 2 seedlings. They were both in perlite until I transplanted the smaller one to the silica gel. So I'll have a side by side experiment here.
 
BobCajun said:
What brand is it? I'll see if I can find out what it is. If you had baked clay kitty litter it would work well, I would think. If it's not baked then it's just going to turn to putty.

I have 2 seedlings. They were both in perlite until I transplanted the smaller one to the silica gel. So I'll have a side by side experiment here.
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it is just a generic store brand but I stole a little from my cat and put it in a bowl of hot water 2 hours ago and it has not gone soft and turned to putty yet. will let it soak and see what happens
 
mauricem00 said:
it is just a generic store brand but I stole a little from my cat and put it in a bowl of hot water 2 hours ago and it has not gone soft and turned to putty yet. will let it soak and see what happens
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Try working it around to mix the water in. If it's "clumping" litter it's raw clay. If it's non-clumping;

" Non-clumping cat litter is often made of zeolite, diatomite and sepiolite. " source

Those would probably work. This one for example. Zeolite is very heavy though, basically rock. A bag weighs 25 lb. The sepiolite may be good though. It's much lighter.

I looked at a Walmart brand of non-clumping and it said it was ground clay though. I also found this interesting on a page I viewed;

"BAD FOR CAT’S HEALTH & HUMAN HEALTH

  1. Clay litter contains silica, which is a known carcinogen when inhaled.
  2. Clumping clay litter contains sodium bentonite which expands to 15 times its volume and forms an INSOLUBLE mass when it contacts liquid. It does the same thing when cats ingest it as they groom themselves after using the litter box." source
BTW, a product called Oil-Dri is baked clay. Might be better than kitty litter. You can get it at Lowes. There are no additives. I viewed their site.
 
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Budley Doright said:
Doesn't RM3 use some type of kitty litter?
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Yeah I think I discussed it with him a few days ago. Kitty litter can be used, but it has to be the right kind. Anything but sodium bentonite I think is okay.

My transplant is looking content in its pot of silica gel. It probably has better aeration than the perlite I normally use. I wonder how fungus gnats will react to it. Probably the same as perlite but maybe something about it will repel them. I think it will support plants better, having more weight to it. Hopefully it won't salt up.
 
What I have found so far is that the silica holds a lot more water than perlite. It gets quite heavy after watering but can go at least twice as long between waterings as perlite, meaning 2 days instead of 1 (with 18 hour light). Could probably go 3 days under 12/12. Growth is similar. Just have to wait until it gets fairly dry to move the pots around.

What makes it better than water crystals is the fact that the size stays exactly the same wet or dry. The water is just on the surface of the granules. So far looks like a good medium. Wonder why nobody used it before, maybe just because other media is cheaper.
 
So we're sure it's safe? The Silica I mean. Wondering if it would work outdoors in my bags. I'm having to water daily due to heatwave/drought and supposedly a stealth grow but has highways going to it :(.
 
Budley Doright said:
So we're sure it's safe? The Silica I mean. Wondering if it would work outdoors in my bags. I'm having to water daily due to heatwave/drought and supposedly a stealth grow but has highways going to it :(.
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It's not cobalt in the blue granules, it's just food dye. They faked it because cobalt is costly and toxic, so yes it's safe, just not the REAL cobalt kind, which kitty litter is not.

Actually it may be better to use a mixture of silica and a light medium like perlite. It may actually hold more water than necessary, making it too heavy which may be hard for roots to grow through. The plant I put in the silica is smaller than the perlite one, but it was from birth anyway so I can't tell if it's the medium or not. I'm going to mix silica and perlite, myself. Probably half and half or 1 silica: 2 perlite.
 
The title of this thread perplexed me so I did some research. Seems it can be used, though they don't mention using it in hydroponics. That said, here's a link so you can see the various mediums they discuss for planting (bulbs).

The brands they evaluated are Tesco brand and Jonny Cat brand (I've never heard of either, suppose you could buy either online)

Anyhoos, here's the link. Pretty informative!

http://pacificbulbsociety.org/pbswiki/index.php/GrowingMedium#kitty


@BobCajun how is that transplant doing so far?
 
roseypeach said:
The title of this thread perplexed me so I did some research. Seems it can be used, though they don't mention using it in hydroponics. That said, here's a link so you can see the various mediums they discuss for planting (bulbs).

The brands they evaluated are Tesco brand and Jonny Cat brand (I've never heard of either, suppose you could buy either online)

Anyhoos, here's the link. Pretty informative!

http://pacificbulbsociety.org/pbswiki/index.php/GrowingMedium#kitty


@BobCajun how is that transplant doing so far?
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Thanks. That's clay kitty litter though. This silica litter is a fairly recent thing. Nobody ever used silica gel as a growing medium that I could find. The transplant is growing, but not fast. As I mentioned in my last post, it was the smaller of the two seedlings anyway, even before the transplant. As I also mentioned, I think it would be better to use silica gel mixed with a lighter medium like perlite, because it gets too heavy by itself when wet. That's how I intend to use it. I tried using water crystals with perlite before but it didn't come out well, because it gets huge when wet then shrinks tiny when dry, so it keeps disturbing the roots. A teaspoon or so expands to like a gallon or something, it's ridiculous.
 
BobCajun said:
Thanks. That's clay kitty litter though. This silica litter is a fairly recent thing. Nobody ever used silica gel as a growing medium that I could find. The transplant is growing, but not fast. As I mentioned in my last post, it was the smaller of the two seedlings anyway, even before the transplant. As I also mentioned, I think it would be better to use silica gel mixed with a lighter medium like perlite, because it gets too heavy by itself when wet. That's how I intend to use it. I tried using water crystals with perlite before but it didn't come out well, because it gets huge when wet then shrinks tiny when dry, so it keeps disturbing the roots. A teaspoon or so expands to like a gallon or something, it's ridiculous.
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Ah, I got ya.

I just did a quick search and found a couple of resources for you here https://www.google.com/patents/US8516741 and here... http://dudegrows.com/use-silica-cannabis-garden/

the latter goes on to talk about how silicon is very good for plants and useful in building strong stems and branches but that's if you're 'feeding' it and to stay soluble, it requires a high pH – greater than 7 and that it cannot be included in a normal, hydroponic two-part feed as it would react with the other components present and this would most likely lead to a nutrient deficiency.

However, as far as growing mediums go, you can use it. I found this for you, and now I'm thinking about trying it myself! https://www.diatomitedirect.co.uk/diahydro-growing-media-shop.html and here's the leaflet that comes with it for instructions to give you an idea of how to use it for your grow https://www.diatomitedirect.co.uk/visageimages/PDFs/DIAHYDRO LEAFLET.pdf
 
I knew about silica as a supplement. I have a bottle now, potassium silicate. It's a liquid. I use it now and then, not like every feeding.

The patent referred to a "fumed silica", which has a gel type consistency when wet. It sticks together, which is why the patent is intended for growing plants in space, zero gravity. It says you can turn a pot of it upside down and it won't drop out. However, the graphs in the patent shows that it actually produces lower plant height than soil, so it wouldn't be advantageous to use on earth. Probably has too little air in the medium, due to sticking together and being pliable, kind of like a blob I guess.

The last one, diatomaceous earth, is a good medium. It's lighter than the silica kitty litter I'm using and holds more water. I just can't get it conveniently where I live and obviously it's too bulky to be shipped cheaply. Thanks for sharing what you found though. I'm stuck with what I can get locally, which is perlite and silica kitty litter. I think it will make an effective medium in the right proportions and both materials are available in many regular department stores or gardening stores. Just gotta watch out for that stupid Miracle Grow "enriched" perlite. It's full of fertilizer. Drained water comes out around 2000 ppm with just pure water being put in the top. Takes quite a while to rinse out too.
 
BobCajun said:
I knew about silica as a supplement. I have a bottle now, potassium silicate. It's a liquid. I use it now and then, not like every feeding.

The patent referred to a "fumed silica", which has a gel type consistency when wet. It sticks together, which is why the patent is intended for growing plants in space, zero gravity. It says you can turn a pot of it upside down and it won't drop out. However, the graphs in the patent shows that it actually produces lower plant height than soil, so it wouldn't be advantageous to use on earth. Probably has too little air in the medium, due to sticking together and being pliable, kind of like a blob I guess.

The last one, diatomaceous earth, is a good medium. It's lighter than the silica kitty litter I'm using and holds more water. I just can't get it conveniently where I live and obviously it's too bulky to be shipped cheaply. Thanks for sharing what you found though. I'm stuck with what I can get locally, which is perlite and silica kitty litter. I think it will make an effective medium in the right proportions and both materials are available in many regular department stores or gardening stores. Just gotta watch out for that stupid Miracle Grow "enriched" perlite. It's full of fertilizer. Drained water comes out around 2000 ppm with just pure water being put in the top. Takes quite a while to rinse out too.
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You're welcome, I don't mind helping out when I can.

Happy growing!!!
 
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