Filter Noodles - Fluval U4

[JMcQueen]

Im currently running a fluval U4 in my tank and noticed that the middle box for the ceramic media is only half full and when you mount the filter vertically, they all fall to the bottom leaving at least half the compartment empty.

Now Im sure that the intention is to ensure adequate water circulation to the media but I was wondering what people thought would happen if i filled it? I have a tin of Eheim substrat Pro that I could use to top it up and fill the compartment but is there a chance that this will over fill it and hinder water flow around the filter?

My thinking is that it would more surface area for the biological filter to form on.

 

[waterdrop]

Good question JMQ! I know that many of our experienced members really like the fluval internals as about the best choice in internals but I don't know what the design intentions were for media amounts. Perhaps one of our members will have tried this or know about it.

If not, you might try finding a support number for Fluval, as they may be able to find some notes or know what would be best. Over time I've come to realize that filter designers sometimes have legitimate reasons for leaving quite large open spaces within filter interiors. In some designs this allows mulm to collect and debris to be held and broken down by heterotrophic/saprotrophic bacteria, processing it into ammonia that is passed on to the autotrophs. The ceramic rings have the job of causing the water flow to slow down and be broken up into small streams of current going in different directions. This slowing down allows larger debris to stop moving and be collected in the open area in many cases. (I know this is the way it works in an Eheim cannister where the rings are the first media that the dirty water runs in to and the large open area is just below.

~~waterdrop~~

 

[OldMan47]

Be careful not to overload any filter with too much media. With a nice lose fill of ceramic media, you can go most of the way to the top of almost any filter and not affect the flow much. that last bit of media that makes things a bit of a tight fit will suddenly cause the flow to drop. If you leave some free space at the top of the space you are referring to, it should not affect the filter flow too much. If your internal is built like my 4+, I would leave at least an inch and better yet two inches of open space above the ceramic media. The filter draws its water from that space and you want the whole area below the impeller inlet to be open to free water flows.