If I add rice hulls at a rate of 12% into my media. Along with vermiculite and perlite at rate of 6.5% each. Would a silica additive be necessary in my water nutrient regimen? At what point am I adding too much silica? Can there be too much?
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I am certainly not a scientist but I donāt believe that Pearlite and Vermiculite break down enough to provide much if any usable silica to your grow medium. Rice is organic and will break down given the proper inoculant, the addition will be slow and metered. I personally do and would add additional potassium silicate (availible) that will also add additional Potassium. Unless you grossly overdue it I donāt see any detrimental effects from that combination. I infuse my medium with insect frass, malt, pearlite, kelp meal, and also use a Silica suppliment by TPS nutrients called Silica Gold, it is fairly low concentration of 1.3% potassium silicate, with a base of soluable silicate at 3%. I have zero problems, but I do have strong stemmed plants.
The assimilation of silica from rice hulls is going to be so slow that the time spent in the grow indoors would not use even a small portion of the potential silica. So my take is add some suppliment. I hope some more experienced growers will chime in.
Marty
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Thanks for the reply. I have been adding 2.0ml/l of silica blast. I have recently found out that you can buy the silica in a powdered form. Which is what 98% of all of the manufacturers of products such as silica blast use. Significantly dropping the price of a silica additive. I wonder if maybe the slight ec (i use 1.3) does cause some chemical or weathering reaction on the vermiculite and perlite. Would need an actual scientist to know that I think. I have been contemplating a reduction of maybe 5% on my cocoa and replacing with burnt rice hulls. I believe they have extra carbon. But the media mix recipe does call for wollastonite. I just didnt need a 20lb bag of it. So I thought I could use de in its place. Now knowing that de is not in a plant available form. Maybe if the media had the perlite,vermiculite,wollastonite that it calls for a silica supplement in the nutrient regimen wouldnt be needed.
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The whole point is to provide silica that the plant can absorb as it needs it. If it is avaliable the plant will use it, if it is not it canāt. I use my soil supplements for the most part for emzyme action and more of a organic taste and smell to the final product. Coco just doesnāt offer any of that being a basically neutral medium. It is my understanding that there are basically two forms of silica, one is not very absorbable the other is. I use what I use because it works. So now that I found that I just leave it alone lol.
Marty
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Just a FYIā¦silica is pretty much inert chemically, so there in no chance of chemical interaction with your nuetsā¦just a word on rice hullsā¦they are usually used as a soil āamendmentā to open the soilā¦just like a perlite or vermiculite and indeed will break down very slowlyā¦also they are going to require a large amount of Nitrogen to break down. Another interesting thing about rice that many people are completely unaware of is that rice (hulls and all) actually contain a large amout of Arsenic
I love rice, and the information has never persuaded me not to enjoy it ! It is a heavy metal and burnt rice hulls would have more Arsenic concentration than the unburnt !!
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They were just talking about that on the news the other day. They said California grown rice has the lowest concentration of arsenic of any rice grown in the US.
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Thanks for the replies guys. I joined this forum instead of rollitup or thc farmer as I thought there would be more adults on here that help and actually have productive conversations. Didnt know about the arsenic in rice hulls. A little more research says that while rice hulls can have arsenic, the silica in them is taken up by the plant through the same pathways arsenic is. The plant prefers the silica over the arsenic and the danger of arseni seems to be minimal. I would assume we would want to keep soil ph 6.0 and above to help discourage any metal absorption. Still not sure if there can be too much silica though.
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I think you will see far more benefit from rice hulls as a soil conditioner, than as a source of absorbable silica, you simply donāt have enough āpot timeā for the breakdown to occur during the course of your grow. I tried a couple different silica supplements before this one and didnāt see any improvement, this one gave me results so I have stuck with it for several years now. I donāt believe I tried silica blast, so canāt comment on that brand either way, and honestly donāt remember the first few I tried anymore. I would just add the silica blast at recommended and leave it at that, unless it isnāt working.
I know a lot of growers use char, but to date I have never used it.
Marty
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Soil conditioner more than a good source of silica box checked lol. Do you think if it were added to recycled bed vs a thrown out one time media. That it would serve a nutritional purpose? Would one want that to happen or would it start to breakdown causing less aeration of the soil? Actually causing more harm than good.
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Your talking about letting it turn in to what is commonly referred to as compost, the breakdown of organic matter via microbe and fungal action. Organic compost is always a good thing to add, just make sure you donāt get unwanted additions like bugs in your grow room.
Marty
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Yeah I guess Iām asking if it would be bad to compost it in your soil bed vs composting it separately beforehand. I understand the soil food web. Just wondering if there would be any negative side effect, besides the bugs you stated. I know I would be better off using an organic living soil if I wanted to reuse my soil bed. Just wondering if rice hulls are an all purpose soil additive or are they really only good for, container grown one use media. Favoring the aeration and sustainability properties for over any chemical.
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Considering the arsenic content I think you could find something better. Just my take, didnāt even know that until @TheMadFlascher put that info out there and when he does I listen.
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I too would side-step the arsenic, although I surf in lake michigan and we seem to have a hexavalent chromium issue when the mills decide to dump cooling water.
Potassium Silicate (cheap - Needs microbes (Amylowhateverfaciens) to help make PAS) - Monosilicic acid (spendy & RTU)
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@cravenbuds , Up here in Northern Cali rice is grown and there are multiple mills so rice hulls are readily available and cheapā¦there is no problem composting rice hulls as long as the percentage of rice hulls is probably 10% or less. Itās common to use rice hulls or almond shells along with a manure, meat by products, green wasteā¦itās all good !
My intent was not to scare anyone ā¦just educate. I believe putting a lot of rice hulls in a relatively small container pot may increase your Arsenic exposure so just wanted to make everyone aware !
BTW you donāt have to worry about ātoo muchā silicaā¦itās relatively inert and a plant will only take up what it needsā¦hope that helps clarifyā¦
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Thank you. I greatly appreciate any knowledge bestowed upon me. I just want to learn and grow the cleanest, highest yielding, highest terpene and cannabinoid content crop I can. 
just the perfect crop is all. Nothing too difficult haha.
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LOL, Hmmmmm something comes to mind here but Iām going to refrain !!!
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Call the fire deptā¦I smell BBP !!! ROFL.
Marty
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Damn, Martyā¦do you ever sleep ??? LOL
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Iāll have time when I die. lol.
Marty
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That is the exact one I use, did a internet search picked that one and printed it out, that close enough for me, I am very cautious about the information I give out, I get way too much junk now. I donāt need to temp my leaves and input every little thing, the standard chart is good enough for me. Every place that wants my email and name all claim that they wonāt give out your info, then suddenly I start getting all kinds of junk from sites similar to one that I made the mistake of giving my email addy to.
Marty
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