2 Smaller Filters Equal To 1 Big Filter

[VickiandKev]

We've just bought a 100gal (UK) / 450L aquarium cheap and need to now kit it out for our fish ... I have a fear of external filtery thingies, plus they are expensive ... soooo would 2 x 1000L/H internal filters each positioned at opposite ends of the tank have the same effect as an external filter pumping upwards of 1500L/H?

If so, this would be great .... if not any ideas on how to cheaply (but reliably) filter a tank of this size?
My knowledge of anything other than a Juwel Bioflow or Fluval 2+/U2 is very sorely lacking and I wouldn't know where to start!!

 

[gzylo]

you can build a sump relatively cheap

search sump filter on the forum or google

 

[Gav935]

Why on earth are you scared of externals? They do a far better job than internals, especially on tanks the size of yours.

 

[rmanpf]

I have yet to do any research on the topic, but your assumption seems correct. I dont see why two smaller filters wouldn't do the job of one big one. I personally prefer externals, but whatever.

 

[three-fingers]

No, the internals would need cleaning out more frequently than one big external, and the externals can use much more efficient media for culturing bacteria, as well as the water having a higher contact time with the bacteria inside the canister.

So to answer your question, an external would be much better for supporting a higher bioload of fish, as well as require less maintenance.

2 x 1000 lph internals would be inadequate for that size of tank unless you only plan to stock it to moderate levels with smaller fish (i.e. no big cichlids).

I would get an external, and then add an internal or two full of filter floss, just for extra water movement and to polish the water more - further reducing the maintenance needed on the external.

 

[pippoodle]

my 300 litre i have 2x external 1500 lph and 1x internal 1000 lph and a diddy internal 400lph (cycling in tank)

definately need external filtering on large tank try for at least 10 X filtering

 

[VickiandKev]

Thank you all for your replies. We don't really have the space for a sump tank unfortunately so I'm looking into an external filter powerful enough for our tank.
We have bought an internal filter that pumps 2300LPH which is recommended to aid filtration rather than be the primary filter, it currently contains filter carbons, but I could change this to filter floss and use this internally to aid water flow, we also have 2 airstone for aeration and water movement.

I have another question, I think I may have found an eheim suitable for our tank within our budget but if it's not available then I'm off searching again .... but would two 1200LPH external filters (one could fit in each closed bit of the cabinet) do the job alongside the internal I mentioned above? They're proper canister filters with all of the media.

Thanks again for all your help and advice

ETA: Oh, and am I correct in thinking a filter should output 3 x tank volume per hour?
I seem to be finding conflicting ideas on this :

 

[three-fingers]

3X would be fine, the more the better as long as you can spread it out enough to it doesnt batter the fish. It's recommended 10x for a planted tank to help keep algae at bay by reducing dead spots and ensure CO2 is spread around enough (even if you arent adding any extra).

I'd just go for a Fluval FX5, great filters and it would be cheaper than two Eheims.