I have a old canister filter eheim prof 2 . The pump on this is not working any more and i was thinking of putting a small pump in the tank to push water through it.
Has anyone tried anything like this before or think of any reason it will not work before i go out and buy a pump

I've never heard of anyone doing this. When you say a small pump, exactly what is the output, do you know? I just checked on the smallest Eheim 2 has a pump output of something like 950 L per hour. You might be better off seeing if you can replace the pump in your Eheim, that might be a better option.

it is possible to buy a new lid for the filter with the pump built in but as this is the most expensive part of the filter it would be easier to get a new filter. The small eheim submersible pumps only cost about £20 for one that will pump 1000 ltr per hour

At one point I waslooking into a similarset up, I would give it a try! If it doesn't work you are only out a couple bucks.

yeah i think your right .I can always use the pump for water changes if it don't work out with the filter.

i had thought of building a canister filter out of pvc and putting my own media in it and just using a regular pump for it. i would say if you try to use an old canister with another pump, remove the impeller assembly from the canister first. i think then it would work.

my first question is: where will you put the canister? will it be under the cabinet
or somewhere higher? the point is the old canister can be used as your media holder,
and a new pump as your driver. since the canister is sealed, yes, you can.

in one of my experiment, i created a canister in a seal plastic container (actually
empty gal of mineral water), stuffed it with bio balls, polishing pad, and scoring
pad as pre-filter pad. what i use is just a power head 2400LPH to drive the water.

all you need is an adapter fittings to connect the spout of the power head to that
intake hose of the canister. it will work great. removing the cap of the old pump
(inside the canister) will improved the water movement inside it.

it will go on a small table at the side of the tank. my idea is to just fill this canister with normal gravel to avoid it blocking up as the other filters on the tank will take care of the mechanical filtration.My main concern was could the canister handle the pressure of water being pumped into it as they are normally designed to have water pumped out of them.

yes, it can... the total head discharge of the pump is the difference in height
between the pump and the lid of the tank disregarding the location of the canister.
btw, what type of pump are you gonna use. my assumption is based on a power head only.

going to use eheim compact 1000
this is the pump i ordered

well i did it hooked it up to the pump and it works perfectly infact the flowrate is probably better than before.

thanks to paul and niki for convincing me to give it a try.

this is a great idea, buy a pwerhead and make a canister filter!