2Nd Filter Choice

[FishyWishie]

Hi all

Im looking into adding a 2nd filter to my 240l tank once i start my cycle as the included fluval 305 external is only giving about 4.2X filtration.

Now the tank has filter connections in the bottom and pre drilled holes in cabinet so im thinking maybe making the 2nd an internal might be an idea ? Any suggestions on what to go for ? Im hoping to make it reasonably cheap so i can spend more on tank furnishings plants and of course eventually the fishies themselves.

 

[OldMan47]

With pre-drilled holes for the inlet and return, I would be seriously looking at a nice external filter to connect to those drilled openings. I am a bit confused by your desire to increase your flow rate through the filter. A filter does its job dealing with nitrogen compounds better or worse based solely on the volume of the media in it, not based on the flow rate. As long as the flow rate is adequate to keep supplying fresh oxygenated water to the filter media, the filter will process the most ammonia and nitrites that can be achieved with that media volume. If you wanted a higher flow rate to optimize mixing, as many plant people do, you can accomplish that by adding a simple power head to the tank. A larger volume, and thus media surface area, filter can add capacity to the biological filter in a tank setting with or without an increase in filter flows. Do not get too concerned about the typical advice you will receive on this and other forums about 5x or 10x filter flows. The numbers are simply values that people have found seem to correspond to the filtration that they are comfortable using. When you look a bit closer, you will find that filters with higher flow rates often have a larger media volume. That added volume is the real key to better biofiltration. What we are not good at doing is defining the volume of media we need in terms of the tank size and stock levels that we have.

 

[FishyWishie]

Not sure if my OP was badly written or not

I have the fluval 305 external filter which as you say will be connected via the pre drilled holes to the filter connectors in the tank.

What i was debating doing was adding a second internal filter to increase the overall flow rate in the tank not the flow rate of the 305 filter.

Ive heard of this powerhead thing before what exactly is it and do i need a specific one for my filter or merely generic ?

 

[OldMan47]

A power head is a simple thing. It is a pump that can be placed in a tank to cause more flow in that tank. I use them most often to power a sponge filter. That means that my sponge filters get much better flow than one that relies on an air stone to move the water. This is a power head made by AC that I have for use in a 30 gallon or smaller tank.

In my case I will use it to power a sponge filter like this one.

 

[waterdrop]

Hi fishy, I have bumped across this thread (or perhaps you've mentioned it elsewhere) several times and have basically just gone away without anything strong to say. Perhaps you've already decided and made a move by now but seeing OM's sponge filter there does make me think of the idea that perhaps one idea would be to add something like that (a sponge or some other sort of smaller internal filter) and to use it most of the time but to also think of it as being available for a Q/H tank when needed. I really think overall your cannister filter may do ok for your tank. And its always something that can be watched and changed.

~~waterdrop~~