neighbor

variance in iAVs sand criteria

9 posts in this topic

At risk of making the experienced iAVsers re-hash the sand criteria yet again, I wonder if you might confirm for me which of the following is most accurate:

From The Sand Selection Guide

Ideal: given: [Crystalline Quartz (with no salts, clays, carbonates or silt)], variable: Very Coarse (1-2mm in size)

Less Ideal: given [Crystalline Quartz (with no salts, clays, carbonates or silt)], variable: Coarse (.5-1mm in size)

vs.

From Directory of Goods and Services:

"...if I were to go to the effort of sifting my own biofilter sand, I think I’d pick the #25 mesh sieve size ...  For extra fast drainage, consider the #20 mesh, but this will somewhat reduce total SSA.  For ‘commercial’ quantities, any capable/responsible quarry will screen to specification."

  • #20 mesh (<0.85 mm), medium course (sic) (as defined on that page)
  • #25 mesh (<0.71 mm), medium course (sic) (as defined on that page)

both of those options fall into the range of Coarse as defined in the Sand Selection Guide (and are less than ideal).

 

why not recommend these sizes given that they correlate most closely with what is presented in the Sand Selection Guide?:

 

  • #12 mesh (<1.7 mm) what remains is very course (sic) sand
  • #14 mesh (<1.4 mm), what remains is course (sic) sand
  • #16 mesh (<1.18 mm), course (sic)
  • #18 mesh (<1.0 mm), course (sic)

I am not anticipating screening my own sand BUT I've found a potential source who has asked what size I want. I'm inclined to say between 1-2mm as per the Sand Selection Guide. I don't want to get this wrong by following the smaller size outlined in the Directory of Goods and Services if in fact what I want is the coarser grain.

 

A simple "Follow the Sand Selection Guide and ignore the Directory" will suffice (or vice versa if applicable).

 

Thank you

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Hi Wendy,

iAVs sand must be inert, free of silt and clay (as far as possible) and must drain properly.  The Sand Particle Size in the Sand Selection Guide is it.  If you follow that, you can't go wrong.

Gary

 

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Thanks Gary, I always appreciate your help.

I doubt I've caught you before the end of your day but ... I have access to a truck (lessee, whaddya call 'em in Australia... ute?) but ONLY tomorrow.

Here's the sand info I got from the place near me (45 min. drive):

we have a product that we call a 8x16 the size range is 1.4mm-1.6mm.  we have a lot in stock right now.  we wash all our material very well.  the SiO2 is at 90.27%. the Sodium Oxide is only .86%. 

 

Do I take my chances without having done a bucket test (hmmm, though I could try to head over there today and look at it) or do you recommend a test regardless of what the vendor says?

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Hey Wendy,

While I don't gamble on horses, dogs or football, I will take a punt on other things in life.  

Sensible gambling means not risking that which you cannot afford to risk.  If you can justify the cost of the sand.....while acknowledging that you may have to use it for something else if it goes wrong.....go for it.

The worst that can happen is that you have a bunch of sand for potting mix.

Gary

 

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Well, my truck access fell through. So I have the time (when I choose to make the 1.5 hour round trip) to go get some sand and test it out for myself. I was kind of hoping that a) it was a good gamble and b) I could therefore get sand before... October, which is the earliest I might be able to find a way to haul it. :( 

I would be hard pressed to use up that much sand if it didn't pan out though, so maybe this is for the best.

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As it turns out, the truck issue was a good thing.

This little episode will also teach me to read things more carefully.  Sodium oxide  becomes sodium hydroxide in water.......and sodium hydroxide is caustic soda.....so we can regard this sand sample as having failed the 'inert' test.

The other issue is that you/ the sand vendor made no mention of what the other 10% comprised.

Quote

I have access to a truck (lessee, whaddya call 'em in Australia... ute?

I admit to having lapsed into the untidy American habit of calling utility vehicles (utes) - or what you folks also call pickups - 'trucks', too.  Normally, we think of a truck as something much larger.

Edited by GaryD (see edit history)

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On 7/18/2016 at 0:19 AM, neighbor said:

At risk of making the experienced iAVsers re-hash the sand criteria yet again, I wonder if you might confirm for me which of the following is most accurate:

From The Sand Selection Guide

Ideal: given: [Crystalline Quartz (with no salts, clays, carbonates or silt)], variable: Very Coarse (1-2mm in size)

Less Ideal: given [Crystalline Quartz (with no salts, clays, carbonates or silt)], variable: Coarse (.5-1mm in size)

vs.

From Directory of Goods and Services:

"...if I were to go to the effort of sifting my own biofilter sand, I think I’d pick the #25 mesh sieve size ...  For extra fast drainage, consider the #20 mesh, but this will somewhat reduce total SSA.  For ‘commercial’ quantities, any capable/responsible quarry will screen to specification."

  • #20 mesh (<0.85 mm), medium course (sic) (as defined on that page)
  • #25 mesh (<0.71 mm), medium course (sic) (as defined on that page)

both of those options fall into the range of Coarse as defined in the Sand Selection Guide (and are less than ideal).

 

why not recommend these sizes given that they correlate most closely with what is presented in the Sand Selection Guide?:

 

  • #12 mesh (<1.7 mm) what remains is very course (sic) sand
  • #14 mesh (<1.4 mm), what remains is course (sic) sand
  • #16 mesh (<1.18 mm), course (sic)
  • #18 mesh (<1.0 mm), course (sic)

I am not anticipating screening my own sand BUT I've found a potential source who has asked what size I want. I'm inclined to say between 1-2mm as per the Sand Selection Guide. I don't want to get this wrong by following the smaller size outlined in the Directory of Goods and Services if in fact what I want is the coarser grain.

 

A simple "Follow the Sand Selection Guide and ignore the Directory" will suffice (or vice versa if applicable).

 

Thank you

I noticed this thread only today.. so ignore this if you have already chosen your sand.  If you go strictly with "between 1-2 mm particle size distribution", I anticipate a difficulty to flood/saturate the filter issue.  You will need a portion of smaller sizes as well such as 0.3 mm and above in the mix for a better result.  Mesh #22 is working fine for me.

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