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Gravel
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Author:  veggie boy [ Apr 3rd, '06, 19:28 ]
Post subject:  Gravel
I know Joel uses what he calls pea gravel - which is apparently common in WA. I am not sure we have the same thing in Brisbane - but of course can buy all sorts of gravels, so I am sure have something similar. What is the best diameter of the gravel?

Any experiences?

Thanks.
Author:  Roskar [ Apr 4th, '06, 07:18 ]
Post subject: 
Veggie Boy,

I have had allok around some landscape suppliers, and haev not been able to find pea gravel so far.

The closest to it is the 10mm road drainage gravel, which seems to be similar to the cracked pea gravel that Joel has talked about. I was thinking of using that unless I do end up finding the "real stuff".

Karel
Author:  steve [ Apr 4th, '06, 10:36 ]
Post subject: 
Hi guys,

The gravel in joels pictures looks like "expanded clay balls" to me.

I'm fairly sure they are made by injecting steam into superheated clay. if you crack one open you will notice millions of little holes in them.

They are used extensively in hydroponics they are EXREMELY porus, which is both good for water retention AND bacteria colonisation.

Joel, am i correct? is this what you use?

You can pick them up at any hydroponics store.

Steve
Author:  earthbound [ Apr 4th, '06, 12:19 ]
Post subject: 
Growing medium or gravel can can come in many shapes and sizes, Some people use small riverstone type gravel, others use volcanic rock, it's basically a case of finding whatever you have in your local area that is available. The particle size should hopefully be around 0.5 - 1 cm in size and the rougher the surface, the more surface area for bacteria to grow on.

I have used the expanded clay in some systems, but for me it is prohibitively expensive, and something that I have only used in systems where weight reduction is an important factor, and only in very small systems.

Here is a picture of the pea gravel that I use, with a lighter as reference. Any medium of similar particle size would do..


Image
Author:  steve [ Apr 4th, '06, 14:27 ]
Post subject: 
Joel,


I hear ya on the price of the caly balls.
I picked up a couple of bag fulls to use in my system quite a while ago.

I think if you can afford them they would be ideal for situations where bed to tank ratio is smaller, as they do colonise really well with bacteria.

But hey what ever works. I was just too lazy to find an alternative :wink:

Sounds like we have a few systems ready to rock. I'd better get off my ass and put thoughts into practice or i'll get left behind :D
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