# pool filter sand



## Kurt Reinhart

I know people have posted that pool filter/blasting sands are good types of sand for aquariums because of their grain sizes. Others have mentioned look for grain sizes between 1-3mm.

Okay, I called a pool supplier and he has pool filter sand that is 20 grit (huh). Below is some information from other sources that I use to logically deduce what the sand should actually look like without seeing it.

Here are the specs on Quikrete pool filter sand
from http://www.quikrete.com/PDFs/DATA_SHEET-Sand-PoolFilter.pdf
"US Sieve Size 20-40
Particle size (0.85-0.425 mm)"

Here is another excerpt regarding different grit sizes.

From http://www.ccsand.com/PricingSheet.aspx
"Sand
Bagged 
Silica Sand 10-20 mesh 50# Bags $10.75/bag 
20-40 mesh 50# Bags $10.75/bag 
100 mesh 50# Bags $8.75/bag 
Silica Blast Sand 16 grit 50# Bags $11.25/bag 
20 grit 50# Bags $11.25/bag 
30 grit 50# Bags $10.25/bag 
70 grit 50# Bags $9.25/bag 
Black Beauty 16-40 50# Bags $12.00/bag 
20-40 50# Bags $12.00/bag 
Play Sand 50# Bags $4.00/bag 
Tube Sand (Winter Only) $5.00/bag "

Based on the above- Blast sand actually comes in a range of sizes (16-70 grit). The 16-20 is probably pretty good though. So be careful if buying "blast sand".

Here's more info.
from http://www.quikrete.com/PDFs/DATA_SHEET-Sands-commercialGrade.pdf

"QUIKRETE® Commercial grade sand is
available in the following sizes:
Grade Predominant Size Range
US sieve number (mm)
Coarse No. 1963 12-30 (0.7-0.6 mm)
Medium No. 1962 20-50 (0.5-0.3 mm)
Fine No. 1961 30-70 (0.6-0.2 mm)"

Here are some basic interpretations. I think that grit sizes are linked to sieve opening sizes and that smaller grit sizes means it collects bigger particles. Does this sound right? Another interpretation is that none of these sands are likely to consist mostly of grains ranging between 1-3mm. I suspect that 16-20 grit (or sieve sizes) will probably have grains that are around 1mm but the average will probably be less.

Okay, so back to where I started. Should the 20 grit pool filter sand be okay? Lots of people have mentioned using "pool filter sand" and I bet that it is ~20 grit...


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## hoppycalif

With a little research through google it appears that 20 grit particles are about 1 mm in size. The smaller the number, the bigger the particles. So, something in the 10 to 20 grit size, which is the same as 10 to 20 mesh size, should be about right.

One reason for trusting pool filter sand is that a swimming pool filter is also not supposed to mess with the hardness of the water, and it has to allow easy flow of water through the sand, which at least suggests that the particle size is big enough to disallow packing down of the sand. People who use that kind of sand have never to my memory reported any problems with it.


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## Gilles

Here is a user of so called "filter sand". In the netherlands we use size: 0.4-0.8mm, smaller sizes tend to form a to thick pack, larger size is not so pretty any more 

Especially for corydora's Filter sand is ideal.


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## Kurt Reinhart

Here's another question for you. I'm terrible at estimating how much to buy. I can estimate the amount that I need based on the dimensions of the tank + 5%. However, I suspect the bags will only list the unit weight and not its volume. Does anyone know the volume of sand in a 100lb bag? I haven't looked at one lately but am guessing 6-8 gallons of sand (or ~1 cubic foot). Does this seem remotely accurate? I remember them being surprisingly heavy for their size...

I saw on the internet that someone estimated that a cubic cm of sand weighs 2.5 g so 100lbs should be = 4.8 gallons or 0.64 cubic feet. So maybe this estimate is more accurate or at least conservative relative to my own...

If anyone recalls how much sand they used to create a known amount of substrate then please chime in?

Thanks
Kurt


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## Gilles

Hmm i can only give you the ammount of sand i poured into my tank last friday. It was 75 kilo's of sand, on a surface of 130cm x 60cm (give or take 10cm due to home made background and overflow box). First i added 60, but i found that to be to little (e.g. 3cm foreground height -> 7cm background height).


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## Diana K

I have used a 30 mesh sand and found that it works quite well. A little coarser would be OK, too. Finer will be getting into the problem with poor circulation encouraging anaerobic spots. 

The mesh or grit size is how many grains of sand lined up equal 1" long line of sand. 30 mesh = 30 grains of sand per inch. 20 grit is 20 grains of sand to the inch. 
There are 25 mm per inch, so saying 20 mesh sand equals 1 mm diameter is pretty close. 30 mesh sand is slightly smaller grains. 

Sand generally weighs not too far off 100 lbs per cubic foot. Not an exact number, though. Especially if it gets wet.
@ 2" deep, 1 cubic foot covers 6 square feet, or a tank that is 1-1/2' x 4'.


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## Kurt Reinhart

Diana,

Thanks. That was an incredible reply. The sand estimates and grains per inch were especially helpful/informative.

Cheers,
Kurt


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## ZooKeeper

Sand, dry 100lb is 1 cubic foot. Not taking into account particle size. 
Further digging: 100mesh = 149microns
therefore, a 10-20 mesh bag of sand will contain sand particles ranging in size from 2000microns(10mesh) to 841microns(20mesh). Friend Gilles is using sand ranging from .420mm to .841mm which translates into a mesh size of 20 to 40. I would ignore Play sand, or Tube sand as those sands will contain a large amount of debri due to the intended purpose. Of course, one could always run the sand through a sieve to obtain the desired particle size - good luck with that. 


Ed


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## ZooKeeper

What the hey, I ignored grit size and then immediately decided to look it up. Unlike mm and micron - which are directly related ie: 1mm is equal to 1micron, grit size is determined by wizards using arcane spells. Ergo, grit size more accurately describes a particle size range and in the case of 16 grit, it describes grains that range from .0310inches to .0650inches. Average is .0430inches. 16 grit sand would be considered a coarser grain sand than 20 mesh sand. 16 grit relates more to 14 mesh. Could you tell the difference? I would say you could. What impact would it make? Try it and find out. The 20 mesh would provide more area per cubic unit than the 16; would be more useful on a larger tank, and would require a stronger pump. I'm assuming you all are talking about fluidized bed filters??? 

Ed


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## Iceterran

50 lb bag created 3-4" in my 75 gal tank, I was surprised to find I didn't need to use more.


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## Squawkbert

Note on particle sizing - when you buy #20 material, it literally means that everything in the bag had to go through a #20 screen (20 wires per inch) to get into the bag. Your largest particles will be close to 1mm, but any smaller ones that were around will also be included, so you should actually think of it it as "#20 and smaller". For some applications, stacks of screens are used and you can wind up with a very narrow particle size distribution based on what screen held up the material - ie #20-80 would be all of the material that made it through #20 and larger mesh only to be retained on the #80 mesh. This leaves you with particles in the 170 to 840 micron range.

FYI - 2800µ particles (2.8mm) corresponds to a 7 mesh, 1.4mm=#14 mesh.


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## Mud Pie Mama

Sorry, but I find this very hard to believe!



Iceterran said:


> 50 lb bag created 3-4" in my 75 gal tank, I was surprised to find I didn't need to use more.


Is this a standard 75 gal? 48" x 18"?? Also, exactly which type of sand? Variety and manufacturer?
Do you have any other mix below this sand? Or rock work in place? Have you pushed a ruler into the sand and actually measured it?

I work in landscaping...plants, mulches, soils, sands, paver and patio stones. Been lifting, moving, stacking, storing, figuring this stuff for 15+ years. I could never figure out how many hundreds of these bags I've held in my arms. But, when figuring for stone projects we use: one .5 cu ft bag (approx 50#) of paver sand will yeild a bed 1" deep for 6 sq ft.

A standard 75g tank (18" x 48") has a footprint of 6 sq ft. One 50# bag of sand will never cover it at 3" deep.


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