Substrate testing at UC Davis

andrewmcleod

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Mar 29, 2005
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Re: Substrate testing at UC Davis

aquabillpers said:
Just one follow-up? We might be talking about different things. The substrate that I am talking about is quartz or silica, made up of irregular 2mm -3mm pieces, and called "builders' sand" or "blastiing sand" in some areas. Water flows through it quite rapidly. That suggests that it doesn't "pack" and thereore has a lot of surface area.

I just filled a 12 ounce water glass with that gravel, and i was able to add 8 ounces of water (by volume) to it before it overflowed. There was virtually no pause between the addition of the water and its disappearance. That suggests that it doesn't "pack" and thereore has a lot of available surface area for the little buggies to roost on.

Bill

But each individual grain does not have any internal surface area, as each individual grain is impermeable. They only have the outer surface area. But a more complex permeable grain, such as a 'fracted clay' like Fluorite will allow water to pass into it, and then it has both the surface area on the outside, and lots of surface area on the inside as well. There is also the additional benefit that the oxygen levels inside the grains may be quite low (or rather the flow rate will be low), so anaerobic reducing bacteria can live happily inside it.

The surface area is not directly related to the porosity, which is what you measured - the amount of water the substrate can hold per unit volume.
 

aquabillpers

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Re: Substrate testing at UC Davis

andrewmcleod said:
But each individual grain does not have any internal surface area, as each individual grain is impermeable. They only have the outer surface area. But a more complex permeable grain, such as a 'fracted clay' like Fluorite will allow water to pass into it, and then it has both the surface area on the outside, and lots of surface area on the inside as well. There is also the additional benefit that the oxygen levels inside the grains may be quite low (or rather the flow rate will be low), so anaerobic reducing bacteria can live happily inside it.

The surface area is not directly related to the porosity, which is what you measured - the amount of water the substrate can hold per unit volume.

It is true that each grain of the substrate that I referenced has no internal structure, so an equal sized grain of Flourite would offer more surface area.
A good point.

But I wonder how the total surface area (internal and external) of a given volume of Flourite would compare to the same volume of 2mm - 3mm gravel? I am thinking that more gravel would fit into that area, thus offering more surface area, perhaps enough more to offset the internal area that Flourite provides. Or maybe not.

What do you think about other substrates that are solid, like the quartz gravel is?

I eagerly await Tom's experiment to settle this question, or maybe to start new ones.

Bill
 

Tom Barr

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Re: Substrate testing at UC Davis

I'd say about 10X the surface area, this does not imply 10x more effective........the grains are generally large and water change diffuse in/out easier in the Flourite.

Regards,
Tom Barr
 

Roseapple1

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Re: Substrate testing at UC Davis

:) Great to hear about new assignment managing labs at UC Davis. Results will have valuable applications. Cheers, Roseapple
 

Tom Barr

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Re: Substrate testing at UC Davis

Well, the electro death skocker for weed control will be used first, most likely for the first time in 2 weeks.

It'll roast the Hydrilla Tubers in the substrate hydrosoil very effectively.

We will place two electrodes(or more) into the soil and add current(, low volts high amps). Much like the fish shocker, but insated of electricity in the water, it'll all be in the hydrosoil, out of the water column.

The electricity will follow the path from probe to probe.

Obviously, everyone will be out of the water and away from the treatment area before current is applied!


Regards,
Tom Barr
 

Wet

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Re: Substrate testing at UC Davis

Also in regards to substrate size, an often overlooked aspect of certain aquarium substrates is ease of planting. I have only used SAPS (alone, with peat, with peat and organics) and Aquasoil Amazonia Normal, but I'd pay the extra ~$20/bagl for the heavier/easier to plant substrate each and everytime. Even with EI/water column dosing. There's only so many times I can replant something before it stops being a hobby and becomes a pain in the rear.

If Barr's Special Substrate ever gets offered and marketed, it holding stems and carpet would sway this buyer.

Just my two cents.
 

Tom Barr

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Re: Substrate testing at UC Davis

Myself as well, but I'm not into product development/making etc really.

I'm much more about information, not making the products you add to the tank.

I know how, I've even talked to a couple of folks about this, but I anticipate nothing will really come of it. Who knows?

ADA has a decent product and a decent price, there is just not enough profit in it to make it worth my while truthfully.
All I need 4 tons of something and only make 2$ on each bag after I spend 4$ for the bag, label etc, 8$ for the product, 6$ for the rent to store it, then spend my life hocking it to get the $$ back.

Nope, not me, I'm wiser than that. Amano charges alot for a reason, then shipping is factored in, it;s not hard t see why it cost what it does.

If there's a simpler easy cheapy way around it, sure, then I'd tell folks, but Soil master is about the best or soil or kitty litter etc.

Tropica has come out with a peat/kitty base which is pretty much what ADA soil is.

Regards,
Tom Barr