How big is fine gravel?
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yvez9
you don't know JACK FISH
i have fine gravel and it is really like sand. maybe 1-2mm in size
Bloo
~ I learn something new ~ ~~~~ every day ~~~~
Yep I agree - no more than 2mm.
3mm max, though that's already moving aways from "fine".
3mm max, though that's already moving aways from "fine".
Bloo
~ I learn something new ~ ~~~~ every day ~~~~
Bloo
~ I learn something new ~ ~~~~ every day ~~~~
hey I tried - I'm sure somewhere 
in there it will tell you exactly 
Dubby
His legend will never die
Technically Gravel is defined to be between 2mm and upto around 75mm
Here is a table of sizes...... I know it doesnt spell out what to use for your corys. Sorry I'm no expert with corys.
32–64 mm Very coarse gravel
16–32 mm Coarse gravel
8–16 mm Medium gravel
4–8 mm Fine gravel
2–4 mm Very fine gravel
1–2 mm Very coarse sand
0.5–1 mm Coarse sand
0.25–0.5 mm Medium sand
0.125–0.25 mm Fine sand
0.063–0.125 mm Very fine sand
Here is a table of sizes...... I know it doesnt spell out what to use for your corys. Sorry I'm no expert with corys.
32–64 mm Very coarse gravel
16–32 mm Coarse gravel
8–16 mm Medium gravel
4–8 mm Fine gravel
2–4 mm Very fine gravel
1–2 mm Very coarse sand
0.5–1 mm Coarse sand
0.25–0.5 mm Medium sand
0.125–0.25 mm Fine sand
0.063–0.125 mm Very fine sand
Good table! Where did you find that?
For cories it's not so much the size of the grain as the smoothness. Rough sand or gravel will wear down or even cut their barbels. Finer grain is better, but not if it has rough edges. Play sand is ideal because it is cheap, fine and smooth (designed that way so it's safe for kids to play with it). It is also inert and non-toxic because kids have a tendency to get things in their mouths.
Pool filter sand is also very good, a little more coarse than play sand, and I suspect more rough edges. I would prefer play sand to pool filter sand for this reason. Pool filter sand is used with much success, though I've never used it.
If you can get natural river gravel (little round stones) that might be OK for cories if you have your heart set on gravel. I don't think they would have as much fun sifting through it, but at least it wouldn't hurt their barbels.
For cories it's not so much the size of the grain as the smoothness. Rough sand or gravel will wear down or even cut their barbels. Finer grain is better, but not if it has rough edges. Play sand is ideal because it is cheap, fine and smooth (designed that way so it's safe for kids to play with it). It is also inert and non-toxic because kids have a tendency to get things in their mouths.
Pool filter sand is also very good, a little more coarse than play sand, and I suspect more rough edges. I would prefer play sand to pool filter sand for this reason. Pool filter sand is used with much success, though I've never used it.
If you can get natural river gravel (little round stones) that might be OK for cories if you have your heart set on gravel. I don't think they would have as much fun sifting through it, but at least it wouldn't hurt their barbels.
I agree - good table! 
Its not so much a case of I have my heart set on gravel - I have this stuff in my tank already. It is like chips rather than globes, if you follow me. The tank was originally going to be set up for tiger barbs, but - yes, I paid a visit to my lfs and spotted baby red angels. I was hooked!
And then I saw orange laser corys So my barb tank has gone bye byes! 
(do I feel another tank coming along soon?? 
)
I think I will put the corys into another tank with sand, just to be on the safe side. At £10 a pop, I don't want them to injure themselves.
Its not so much a case of I have my heart set on gravel - I have this stuff in my tank already. It is like chips rather than globes, if you follow me. The tank was originally going to be set up for tiger barbs, but - yes, I paid a visit to my lfs and spotted baby red angels. I was hooked!
And then I saw orange laser corys So my barb tank has gone bye byes! (do I feel another tank coming along soon?? )I think I will put the corys into another tank with sand, just to be on the safe side. At £10 a pop, I don't want them to injure themselves.
Bloo
~ I learn something new ~ ~~~~ every day ~~~~
Very good table indeed! I think it came from this website
LoachLover
Snails Beware
It's just a larger grain of sand is what it looks like for the most part.
Dubby
His legend will never die
I dont remember where I got the table from ; one of those internet sites ... Really handy when buying sand & stuff esp when it says something like 'coarse' on the pack
; one of those internet sites ... Really handy when buying sand & stuff esp when it says something like 'coarse' on the pack 
I noticed that the table only denotes differences based on the average size of the grains. There really is no mention of the roughness of the particles. This would be a parameter that is really independent of the overall size.
Next time you think one gravel is "rougher" than another, pull out that magnifying glass and take a good close look -- a lot of these rocks are very rough, just on different scales.
The roughness of the gravel affecting the cory's barbs is mainly a secondary effect. Water quality is first and foremost what affect thier barbs the most. Poor water quality will hamper regrowth if the barbs should happen to be cut on a rock... but the rocks themselves don't slice the barbs off for example. The best indicator of this is to look at where corys occur naturally -- many species devleoped in rocky bedded streams. It is also just anecdotal evidence, but there is a report of corys being kept over a crushed glass substrate with clean water at http
/www.skepticalaquarist.com/docs/fishes/catfishes.shtml with no barbel erosion.
Next time you think one gravel is "rougher" than another, pull out that magnifying glass and take a good close look -- a lot of these rocks are very rough, just on different scales.
The roughness of the gravel affecting the cory's barbs is mainly a secondary effect. Water quality is first and foremost what affect thier barbs the most. Poor water quality will hamper regrowth if the barbs should happen to be cut on a rock... but the rocks themselves don't slice the barbs off for example. The best indicator of this is to look at where corys occur naturally -- many species devleoped in rocky bedded streams. It is also just anecdotal evidence, but there is a report of corys being kept over a crushed glass substrate with clean water at http
/www.skepticalaquarist.com/docs/fishes/catfishes.shtml with no barbel erosion.Similar threads
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