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bigrift 09-29-2010 04:13 PM

grivity filter
so i was thinking of a way to filter the big tank im makeing and i came up with a idea to use gravity instead of eletric to power the pumps. i dont really know much about this stuff so ill post my idea and if anyone knows any physics then tell me if it will work of not lol.

ok so my idea was to build a biofilter that hung stright up and down off the back of my tank. a tube would run from the top of the tank (drilled and fitted in the back of the wall) would run straight down threw the filter and then the return would simply be a tube on the bottom going straight into the tank about 2 feet below the inlet. my hope is that gravity will feed the filter and return the water back to the tank without any pumps and sutch but im woundering if the presure of the water in the tank would keep it from flowing back in and instead just filling up the filter and tubes with water and sitting. so a way i thought of to combat this is to have the inlet take in 3x the water the outlet will put back in causeing almost a suction.

so thats my idea and yeah it may be silly but i really would like some imput on this dont be shy if it wont work tell me lol

mozart531 09-30-2010 03:32 AM

1 Attachment(s)
Is this kind of like the design you were thinking of? (The grey box is the biofilter)

Attachment 17721

I'm afraid this design won't work without some sort of pump. While gravity does pull on the water in the tube, gravity also pulls on the water in the tank. The water in the tube won't move without something pumping it through. If you put an airstone in the bottom you might be able to draw water up from the bottom of the tank (the rising air bubbles pull water up with them). It depends on how big your aquarium is and what your biofilter looks like. The bubble-method usually doesn't generate a lot of flow.

SinCrisis 09-30-2010 08:43 AM

If the box is level with the tank it wont pull water regardless of intake size. For gravity to work, the box will need to be lower than the tank. However once the bottom area fills up gravity wont pull it up to the tank so it will site idle. You will need a pump no matter what to move the water.

AaronCombs 09-30-2010 09:04 AM

I've tried to pull something like this off as well. Would be great for a power saver. However never worked.

SinCrisis 09-30-2010 09:09 AM

Well, a while back i saw an article about creating green energy... where a system used solar power to power a pump that pulled water up to a platform during the day and at night the water is let down via gravity and it runs through turbines to generate even more power. It could be applied to a fishtank if you use gravity to pull-water through a turbine and have the power generated there power the pump to push it back into the tank. That might be beyond anyone's capabilities though...

AaronCombs 09-30-2010 11:59 AM

lol actually and sadly that would work. However you'd have find out how much power the pump needs, then how much power the turbine can generate off a 2" or 3" Pvc pipe...

With all that said, you'd also have to compare life of turbine and pump vrs cost of just using electricity over that given time frame. To see which is cheaper. Pending the output of the turbine, which would have to be a mini ... you might be able to setup a battery system (grid) to hold the power. This could also in turn possibly power the rest of the aquarium.

On another note if you had solar panels and the grid in place, you could be green doing that instead of the turbine.

SinCrisis 09-30-2010 12:08 PM

get a bunch of hamsters to run on wheels... jk.

AaronCombs 09-30-2010 12:17 PM

lol mice work better.. at least mine did it more than the hamsters.

bigrift 09-30-2010 02:25 PM

darn... i figured it wouldnt work but hey it was a good idea lol... it wasnt so much to save energy but just to have something diffrent ya know. i was reading a artical (when and if i get permission to post the link i will) a guy used a bubbler to pump air into his filter and it caused the water inside to push out the the bottom and when the filter was low on water the bubbler shut off alowing a flapper to open at the top of the tank to let more water fill in and it would do this over and over serveal times a minute (i think it said 2 times a min). the air in the filter was released threw a fitting into a hose that went to his stone in the tank to keep it from being just one big rush of air. i guess he figures letting the water sit for about 30 sec in the filter alowed the bacteria to really do its job and keep it free of harmfull stuff.... i dunno sounds like alot to me i probuly wont do it but he dose sell the plans for 25$ on his website. cool idea though and ill post a like if he says its cool to.

AaronCombs 09-30-2010 03:31 PM

What he setup is a basic filter... the air causes an internal circulation moving water to filter. I have one on my own tank. Costs about 5 bucks at most to build. Very simple... need a bottle, knife, air line tubing, fork (to make some holes)... then some gravel, filter media, and some active carbon ... and your set. oh and an air pump lol

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