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Post by lloyd on Sept 11, 2015 14:05:39 GMT -5
I've been using some coarse silica sand for a few years now. I've cleaned it with tap water until the water is almost completely clear, then wash with distilled water. I've noticed that some plants, particularly some dews and utrics have dwindled in a mix of peat with this sand. When I repotted into peat/perlite, the plants took off.
For instance: Utricularia pubescens never did well, with tiny stolons that never lasted very long. I tried repotting and it just dwindled and seemed to be on the way out. Thinking it might be the sand, I changed it into a medium of peat/perlite. It is much thicker than ever, with much bigger stolons and it is growing multiple flower spikes.
My petiollaris dews might be another example. Pygmy dews on the other hand do really well in the peat/sand mixture. So if you notice some plants not doing well in sand/peat, try changing the mix to peat/perlite.
Then you will have pots & pots of pure peat & perlite
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Post by shoggoths on Sept 11, 2015 14:28:37 GMT -5
Does your peat/perlite mix seems more airy than your peat/sand one ?
My peat/sand mix tend to become more compacted than my peat/perlite one. Could explain the difference.
In theory, silica sand is relatively / chemically inert in our growing conditions...
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Post by hal on Sept 11, 2015 16:02:31 GMT -5
Then you will have pots & pots of pure peat & perlite Perfectly prepared for potting pings! I've also had mixed results with that sand/gravel, Lloyd. And my ping collection went way downhill when I switched to a mostly mineral media. I have had the most success with Pings in a 50/50 peat/perlite mix with about 1/5 part of limestone screenings added for alkalinity. I keep them in a tray with 1cm of water that's allowed to dry out and stay dry for a few days. Works great for the large leafed varieties and the hybrids. P. moctezumae did best for me in a more peat-rich mixture and continuous dampness. The small, rosetted varieties like debbertiana and esseriana like it dryer and with less peat.
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Post by lloyd on Sept 11, 2015 21:38:00 GMT -5
Excellent comments guys. I'm going to change my ping mix.
This sand is pretty coarse so peat mixes with it are fairly airy. Finer sand can cause compaction.
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Post by troutddicted on Sept 12, 2015 15:02:25 GMT -5
Perlite is mostly composed of silica. Going off memory here so you may have to double check that LOL
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Post by Apoplast on Sept 13, 2015 12:05:21 GMT -5
Hi Lloyd - Sounds like you may have gotten some silica sand from a new source (that can happen even with the same packaging, if the company changes quarries). I had this happen to me a couple years back and I lost a shocking number of plants. I tried acid washing the sand to get rid of the calcareous component. It did not work, and killed my plants just as fast!
Since this point, I now tentatively buy new brands or new stock, and check the quality first. I heavily rinse about a handful of sand. Then I take a small canning jar and add about 2-3 times the volume of white vinegar. Swirl it. I let it sit for about 2 days. When I return to it I give it another swirl. If the once clean sand goes cloudy, it's got soluble material in it that can harm sensitive plants. Don't use that sand! There will be no recovering it.
I used to use sandblasting sand, as that is supposed to be pure silica, but it varies. Right now, the best sand sources I have are for pool filter sand. Those companies tend to worry about making water cloudy (i.e. having soluble components in their sand), as it would be bad for business. Regardless, I now strongly advocate for testing your sand before using it.
I hope that helps.
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Post by Apoplast on Sept 13, 2015 15:08:16 GMT -5
Hi all - Okay, so I couldn't help it. I wanted to share what "bad" sand looks like when you do a vinegar test. Below are two small jars that have been sitting with sand and vinegar in them for some time, but they looked much like they do now. The jar on the left looks okay, though there is a hint of what is to come because I moved the jars to photograph them. In the one on the right, the vinegar has clearly turned rusty. That is from the iron in the sand. Here is the picture of what they look like settled - the "before" photo if you will: The next photo is after I have swirled the sand in the vinegar. You'll see that in the one on the left liquid has gone cloudy. That is the dissolved calcareous component of the sand. This is an indicator that the sand has minerals that will dissolve and release salts in acidic conditions - like those in peat based soils. This sand will kill your sensitive plants! The one on the right is still rusty, but now has a slight cloudy aspect to the vinegar. This sand was not toxic to most of my plants, but they didn't love it either. It's not the iron content that seems to be the issue - I've used other sand that formed this rusty vinegar but remained clear when swirled and plants did very well. It's the slight cloudy component - again evidence of minerals dissolving in acidic solution. Here is the "after" photo: Unfortunately, you can't get information on this all with TDS. The vinegar has a high EC and you aren't getting the information you want. The toxic sand on the left in the photos was easy enough to rinse with RO down to a low TDS. It was the breakdown of the dissolvable minerals over time that caused the decline in the plants. After being rinsed, he sand I use now (and I use a lot growing so many tuberous sundews) can sit in the vinegar for over a month and when swirled doesn't make the vinegar go cloudy. For those of you wondering, yes salts can be clear in a solution, adding table salt to a glass of water makes that obvious, and that would of course kill CP's. But, unless the salts were only on the surface of the sand grains, there will be degradation of the grains, and they will produce the same cloudy liquid. So far this has been the best method I has found to check the "quality" of the sand I am using for growing CP's and other salt sensitive plants. It's a fast, cheap, easy way to test your sand. I hope this helps.
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Post by troutddicted on Sept 13, 2015 19:58:39 GMT -5
Wow, such an informative post, thanks for this Apoplastic water movement.
Science, bitumen! -Sir Jesse Pinkman
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Post by lloyd on Sept 13, 2015 20:39:50 GMT -5
Got my bottle of sand & vinegar. I'll see what happens.
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Post by Apoplast on Sept 14, 2015 20:34:29 GMT -5
Thanks Trout! I'm always excited when a post of mine is informative (though I'm pleased with interesting or entertaining too)
Lloyd - I very much look forward to your results! I've only been able to test this with sands from across the upper Midwestern States (about Ohio to the Dakotas). Places don't tend to ship sand very far as it's heavy and not high profit.
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Post by Apoplast on Sept 21, 2015 15:20:38 GMT -5
Any update Lloyd? I'm waiting with bated breath - or at breath that smells like bait.
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Post by lloyd on Sept 21, 2015 16:04:04 GMT -5
When you shake it really hard, the vinegar clouds up. I think that no matter how you clean the sand, when you rinse the sand, more particles are abraded off and cloud the water. Anyway after a few hours, the particles settle out and the vinegar is crystal clear. I plan on testing the TDS of the vinegar with sand then plain vinegar and see if any minerals leached out. Do you think enough time has passed?
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Post by Justintime on Sept 21, 2015 21:58:12 GMT -5
Wow good to know I'll be testing my sandblasting sand asap! Thank you for the information.
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Post by Apoplast on Sept 22, 2015 22:53:37 GMT -5
Hi Lloyd - Depending on the degree of cloudiness, I'd be concerned. Of course, this test is not diagnostic. Still, the cloudiness is likely derived from minerals that have been freed by the solvent action of the vinegar (a weak acid - much like peatmoss). What has come out may be terrible for the plants, or it may not. It would take much more detailed (and somewhat more expensive) analyses to know precisely what has been dissolved.
I don't think that the shaking you've done on the sand will result in enough abrasion to create fine particulate matter mechanically. Typically, sand is around because it is the remnant minerals that are harder than the dissolved surrounding minerals in the parent material. It's the abrasion and chemical resistance that results in sands durability and persistence. This is why quartz (crystalline SiO2) is so prevalent in mineral sands (as opposed to biological sand, which are a completely different tangent for a reef aquarium forum). Quartz is incredibly durable.
The likely cause of the cloudiness you are seeing is dissolution of minerals freeing small particles. I like the idea of measuring the TDS of the vinegar and the final solution. Personally, I would have instrumentation issues and not get usable data. TDS meters, as you know, measure the electrical conductivity of a solution. Vinegar is quite conductive on its own. My meter is maxed out by vinegar, and even at the upper threshold I don't trust the numbers. Side note, a fun little experiment looking at the electrical conductivity of solutions is to check the conductivity (most dramatically with a light from a completed circuit) of a solution with vinegar, another solution with ammonia, and then after you mix the two. Anyhow, I'm interested if you get usable results. Regardless, I'd toss the sand you think is toxic that created the cloudiness and find another source.
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Post by lloyd on Sept 23, 2015 9:41:24 GMT -5
I tested ordinary vinegar-510 PPM TDS. The supernatant of the sand and vinegar was 470 PPM, TDS. Clearly this isn't a very useful measurement. It's just measuring conductivity and not total dissolved salts. The only thing you can get from these measurements is that my sand is probably not leaching anything into the vinegar and so would probably not leach anything into the water in the soil medium.
The next step is to decant the clear vinegar when the cloudiness settles out, measure the volume and let it evaporate. The water and vinegar will evaporate. I'll see what's left over, weigh it and go from there.
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