# Bio Filter Idea



## Phoenix17 (May 2, 2010)

Hey guys. I always like to have a project and decided to make a second filter for my 2.5 gallon tank. I find the filter that's on it to be just adequate. I wanted a mechanically pumped gravel vac that would just put all the water back in the tank because 2.5 gallons goes fast. So this mechanical filter will get established with some bacteria and stuff for when I get my 10 gal, it should be easier to start cycling the new tank.
So, my idea:

You may have seen the specifically designed "bio balls" or whatever they're called. You run water through them and they're designed to have a BUNCH of surface area for bacteria. My idea was to run water up through sand, so that the sand rolls and boils but eventually only goes so high that it doesn't run out of the container but the water does (that part I know can work). like sand in an upside down funnel, with water running up through it.

The part I need opinions on is the idea that sand makes a ton of surface area for the bacteria to collect on. What do you guys think? about 1.5 cups of sand running about a gallon per minute? would that help break down the ammonia and nitrite for a 2.5/10 gal tank? I don't know how I would test it scientifically.


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## emc7 (Jul 23, 2005)

Both ponds and large commercial aquariums use sand in filters. They usually have big rocks, small rocks, gravel and sand so that somehow the sand doesn't end up in the tanks. Sand does have lots of surface area. I've seen an internal filter for 30 gallon tanks that used sand in a closed compartment and the owner complained the sand got loose. So I wouldn't try a sand filter for a tiny tank unless you don't mind sand in the tank. I suspect a large hunk of sponge would be effective enough and be easier to clean. But if you get something working, I'd like to see pics/diagrams. The sand-filled pond fillers are cleaned by "back-flushing". Which is to use the pump that usually runs pond water forward through the filter to pump clean water backwards, hopefully taking the captured waste down the drain.


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## Mikaila31 (Nov 29, 2009)

there are sand filters for larger home aquariums. Large tanks, I really don't know if you can make one small enough for a 2.5 gal... 

But yeah generally fluidized bed filters are a option for large 100+ gal tanks as one method of filtration. They are sand based filters, though I think you would want some mechanical in their too.


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## bmlbytes (Aug 1, 2009)

The sand is mechanical. The sand will trap debris.

This type of filter is commonly used in pools. If you go to a local pool supply store, you can buy a big bag of pool filter sand for about $8


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## Phoenix17 (May 2, 2010)

Mikaila31 said:


> there are sand filters for larger home aquariums. Large tanks, I really don't know if you can make one small enough for a 2.5 gal...
> 
> But yeah generally fluidized bed filters are a option for large 100+ gal tanks as one method of filtration. They are sand based filters, though I think you would want some mechanical in their too.


I agree, it's a huge undertaking for a 2.5 gallon tank. But I believe it could work. And as long as I don't have other projects, I'm going to keep working on this system. First things first, the mechanical filter!

If I ever do get something neat going, I will surely post it.


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## bmlbytes (Aug 1, 2009)

Again, you dont need any extra mechanical if you are using sand. Unless it is a very little bit of sand, the sand will trap anything going through it.


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## Toshogu (Apr 24, 2009)

I would suggest making a sump and doing it in there, or turning a 5gallon bucket into this sand powered canisterfilter you wanted. Either way, tinker away. There is no such thing as too much filtration. There is such a thing as to much flow. And you know you have too much flow when you have fish pressed against the glass, and others that look like they in a drying machine


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