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DIY Biomedia?


OziOscar

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Hi Guys!

I'm planning to have a go at a DIY trickle filter over the Christmas break and was wondering what might be a valid alternative to bioballs, owing to their high-ish price.

I've heard tell of people using clear plastic drinking straws cut into 25 mm sections and filling their chamber with those. Would that work? The surface area seems to be perhaps high enough to encourage bacterial growth.

What other materials have you used or heard of being used with a reasonable degree of success?

Cheers - OziOscar.

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I use a combination of bbq rock and broken oyster shells in my diy filter. All up the media cost me $25, and it filters exceptionally well, buffering the water at the same time.

:8

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It all depends on how heavy you want your biofilter to be. Any beads are great. you can get ones that float or sink. I've used bean bag balls with a lot of success. Gutter guard is good too. You just need to maxamise the surface area of the media. I wouldn't use oyster shells or anything like that as they are not that great for surface area. Basically anything under about 5mm will have an equivilent or higher surface area as bioballs. The gutter guard and things will be about the same per volume.

Adam

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I wouldn't use oyster shells or anything like that as they are not that great for surface area.

The oyster shells would be in the filter as a buffing agent more so than as bio media.

I too use shells(though beach shells) in my canister filter as a buffing agent, after 2 months or so you can visibly see them deteriorating/disloving.

Lata

Matt

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Hi...

I'm just wondering if we can use the tape form a cassette or a video?

Cheers,

ib

I wouldn't but thats because i don't know what it's made of or what coatings it has.

You can buy rolls of packing tape pretty cheap, it'd probably do OK.

Lata

Matt

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Im using 2x60L plastic tubs (stackable), one inside the other, the bottom one forms

a sump, the top one has the media...

top layer, polyester foam

middle layer, gutter guard, cuts into sheets to fit (4 rolls $2 each)

bottom layer, scoria (same as bbq rock, volcanic rock)

a bulkhead attached to sump which feeds external pump, works great and cheap,

for 2 4ftx2x2 tanks...

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Thanks for the tips, everyone!

I'm guessing that scoria would seem to be the go. The only thing is, what are its chemical properties? Does it alter ph? gh? kh? Given that it is reddish, does it have any serious amount of soluble iron (or oxides etc thereof) that might have any unpredictable effect?

Thank you for the hint on bagging the straws. That sounds like a wise idea. If the scoria has any odd properties, then I may go down this path... else the ceramic insulators - if I can score some at the right price. :)

Weight isn't really an issue - I'm a big bugger so pulling it out for service shouldn't be too much of a hassle. :D

Just on the using old video / audio tape: I wouldn't do it. The oxide coating on the tape is an iron - chromium - only-God-knows-what blend that will delaminate from the tape very easily in water after a few months. The chemical reaction is a potential problem, as would be any fragments finding their way into pumps etc...

Thank you so much for your help.

Cheers - OziOscar.

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my filter is made of two 25l canisters the first has a central perforated core that is removable for cleaning its full of rocks, around the core is 4 rolls of gutter guard. in the second canister at the bottom is crushed shell for buffer and fine filter ,then down into the secondcore of filter foam and filter wool, more foam , pump..

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Sorry guys I have been busy and missed this thread :p

Bbq rock is not scoria, it is the rock which you can buy from any bbq supplier and it is designed to go under the gas burners in a gas barbie. They act as a heat sink i guess, spreading the heat evenly under the grill and plate.

Scoria is red I think, this stuff is brown. It is similar to pumus, full of holes and cracks, but a little heavier.

I find it has a great surface area, and has been working very effectively in my filter for 3 years now.

Adam is right about the oyster shells, and I would never recommend them as a sole media. But if you have enough other media they make a great addition to any african tank, and they are free :^:

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Guys,

I thought I'd post this so that you get the idea of what sort of surface area you get for you media.

5mm Rock 600m2/m3

12mm Rock 420m2/m3

25mm Rock 210m2/m3

50mm Rock 105m2/m3

12mm Ceramic Rasching Ring 264m2/m3

OviFlow BioBalls 500m2/m3

BioMate BioBalls 528m2/m3

I don't have a figure for the gutter guard but I don't think it will be all that high, in the order of 300-400m2/m3. I'll also see if I can find the figures I have for sand in Fluidised beds, from memory it'll be around 1000m2/m3.

Also as a rough guide in freshwater systems you can assume that 1.6m2 of biomedia Surface Area is required for each gram of ammonia loaded onto the system daily.

Adam

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You can buy expanded fired clay balls diameter from about 5mm to about 9mm, porous right through, inert. They are light in weight for the volume. I imagine they might work similarly to Matrix, being similarly porous, the pores are very small but somewhat bigger than the matrix ones. They are used as growing media for hydroponic growers. You can get a big bag (about 15kg at a guess?) of them for around $40 I think? I have used them as biomedia successfully and reckon they work well. If you put them in water they float at first but sink when they soak up the water.

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Hi Adam!

How do you calculate grammage of ammonia per day? Is there a rule of thumb that might be useful?

Cheers - OziOscar.

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