# Schamotte clay or Grog



## Jamie @ Vertex (4 Dec 2013)

Having taught pottery for a few years I have worked with quite a few different clay type. One, often used to give a raw, fine clay more tooth is grog or schamotte. This is essentially a bisque-fired clay, typically white or red. I was wondering if anyone had experimented with this in substrate for freshwater? Being highly porous and hard, it may present an interesting addative. With the red form being heavy in iron and manganese, it resembles laterite.

cheers,

Jamie


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## dw1305 (5 Dec 2013)

Hi all, 





Jamie @ Vertex said:


> This is essentially a bisque-fired clay, typically white or red. I was wondering if anyone had experimented with this in substrate for freshwater? Being highly porous and hard, it may present an interesting addative. With the red form being heavy in iron and manganese, it resembles laterite.


 I think it should be fine. Have a look a this thread <Darrell's (dw1305's) soil thread | UK Aquatic Plant Society>.

cheers Darrel


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## prdad (5 Dec 2013)

I use LECA as a substrate in a few tanks. Which is a clay fired when still slightly moist which causes it to expand into a very porous material. Best result was when I mixed it with peat with an under layer of osmocote in a low tech.  My wife is a silversmith so I still have access to a small kiln. Maybe time to start experimenting again. Could be interesting to take impressions from suitable rock. Is bisque fired inert? Or will it break down in water?


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## prdad (5 Dec 2013)

Just read your link Darrel. Excellent stuff.


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## Jamie @ Vertex (6 Dec 2013)

prdad said:


> I use LECA as a substrate in a few tanks. Which is a clay fired when still slightly moist which causes it to expand into a very porous material. Best result was when I mixed it with peat with an under layer of osmocote in a low tech. My wife is a silversmith so I still have access to a small kiln. Maybe time to start experimenting again. Could be interesting to take impressions from suitable rock. Is bisque fired inert? Or will it break down in water?


 
Bisque is essentially inert.  It is what one calls the first sinter point, where the clay molecules bind in a permanent, but relatively weak structure.  The next stage would bring them to a true stone-like density and structure, like we know in stoneware and porcellan.

Darrel, thanks for the link.  I think I may play with the schamotte and see if there are benefits or disadvantages.  I suppose we do get a bit OTT with substrate.


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## dw1305 (6 Dec 2013)

Hi all,





prdad said:


> I use LECA as a substrate in a few tanks


Can you get LECA that sinks? I've used it a lot for hydroponics and trickle filters (and in canister filters), all the stuff I've bought in the UK floats, but I'd be very interested in some sinking LECA. I still have a regular trickle of 2mm sieved sintered clay from the lab. furnace, but I've been adding it to the potting compost, rather than saving it.

cheers Darrel


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## prdad (6 Dec 2013)

I've got a couple of ton in a few trout based aquaponic beds. Theres a low percentage that floats so I just chuck that back into the beds and use the stuff that sinks. I've got two sizes <10mm and >20mm. 20mm is better for the trout beds and 10mm looks more 'scale' in the planted tanks. I use Robin at Claytek - robin@claytek.co.uk. Just be aware most suppliers quote neutral ph but I've found they use a mineral in production that was giving me ph readings of 8. Hence me using peat with it.


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## Curvball (7 Dec 2013)

Hey Jamie, good to see you here 


Posted from the comfort of my iPhone...


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## Jamie @ Vertex (9 Dec 2013)

Curvball said:


> Hey Jamie, good to see you here
> 
> 
> Posted from the comfort of my iPhone...


 
C,

you knew I had to turn up sometime.  How are things?

cheers,

Jamie


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