# [Wet Thumb Forum]-Fluval 404 Priming Problem



## orgetorix (Sep 23, 2003)

I have a Fluval 404 canister filter that I want to use as a pump to diffuse CO2. The problem is that I can't get the darn thing to prime. I followed the instructions in the manual and...nothing. It seems that it doesn't want to pump up the the return.

Here is something I did do to get it to work. I took it to my kitchen and filled the sink with water. I placed the filter on the floor and was able to get it to siphon water from the sink to a bucket on the floor next to the filter.








When I move the hose back up to the sink though (similar to the situation it would be in my tank) the siphon stops.








I did some fiddling around and got it to finally work in the second diagram, but I'm not sure how and was unable to replicate in the aquarium. All help is greatly appreciated. Thanks.


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## orgetorix (Sep 23, 2003)

I have a Fluval 404 canister filter that I want to use as a pump to diffuse CO2. The problem is that I can't get the darn thing to prime. I followed the instructions in the manual and...nothing. It seems that it doesn't want to pump up the the return.

Here is something I did do to get it to work. I took it to my kitchen and filled the sink with water. I placed the filter on the floor and was able to get it to siphon water from the sink to a bucket on the floor next to the filter.








When I move the hose back up to the sink though (similar to the situation it would be in my tank) the siphon stops.








I did some fiddling around and got it to finally work in the second diagram, but I'm not sure how and was unable to replicate in the aquarium. All help is greatly appreciated. Thanks.


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## Stevenl (Mar 31, 2004)

If your problem is that you can't get enough water into the hoses to get the filter to prime, here's a little trick that you can try. First make sure you fill up the filter with as much water as you can. Then, close the shut-off valve on the "Aqua Stop" (as named by Hagen) and deattach the whole thing from the filter. Now, open the valve again and let it siphon out some water. Make sure you have a bucket ready to catch the water though








Close the valve again and attach it back to the filter. By now the hoses would be filled with water and the filter should prime properly.

HTH!


















66G tank with 3 wpg NO Fluroscent,and 50/50 flourite substrate, UV sterilizer, DIY CO2 (upgrade soon!)


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## anonapersona (Mar 11, 2004)

How deep is the outlet in the tank?

If there are bubbles that need to be released, and the outlet is deep in the aquarium, it may be too difficult for the pump to overcome the pressure. Try it with the water level a bit lowered, so the outlet is above the water or nearly so.


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## Cichlidcat (Sep 29, 2003)

Did you use the primer pump until water was being pumped back into your tank.

I have a 204 and the flat platic peice that is sticking straight up in front of the inlet/outlet ports is the primer pump. Pull it up and push it down until water is being pumped back into the tank. Tank should be 1/2 to 3/4 way full when you do this.

I'm not to sure about using your Fluval for a CO2 diffuser though. The pump chamber will get a gas bubble in it and will make the empeller chatter. I would just use a power head or one of those Mini Vortexs.

Hope this helps


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## George Willms (Jul 28, 2004)

I had a very similar problem to yours orgetorix. Do you want to know how I solved it?

I bought an Eheim! Problem fixed.









George

4 tanks: 5.5, 12, 29, and 45 gallons.

More complete tank specs in profile.


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