Low Flow Good Filtration

[JaredL]

I've read from many sources that recommend you have a filter gph that is 5x your tank size in gallons. My question is:

How can I achieve this and still have a slow flow tank for fish such as bettas?

I've found that anytime I follow this 5x rule of gph I end up with a fairly strong current in my tank. Does this rule only apply to HOBs since they notoriously over state their actual gph?

[GardenStateGoldfish]

Sponge filters would be my recommendation on a good filtration low flow. They are amazing. I have heard the 5x turnover rate, not really sure where that came from but I would say that a fish like bettas would not appreciate any significant flow. They are also a labyrinth fish so that rule may not even apply to them. 

[Schwack]

5 minutes ago, JaredL said:

I've read from many sources that recommend you have a filter gph that is 5x your tank size in gallons. My question is:

How can I achieve this and still have a slow flow tank for fish such as bettas?

I've found that anytime I follow this 5x rule of gph I end up with a fairly strong current in my tank. Does this rule only apply to HOBs since they notoriously over state their actual gph?

My bettas do ok with a combo of a sponge filter for bio filtration and AquaClear HOB's to keep the water nice and clear for me. The AquaClear's are adjustable, so you can turn the flow down to a near drip. The adjustment plus the customizable filter media is hard to beat. They're also relatively easy to baffle if the lowest setting is too much for your fish. I've heard a few folks say they've had overflows with them, but after a year of running two of them I haven't had that problem.

Strangely, both bettas I keep seem to really enjoy swimming into the waterfall from the HOB filters. Occasionally, I turn up the flow (after a water change, for example) and both of them will sit under the heavier splash and swim straight up. 

[CT_]

Some fish may like or dislike flow but I too don't understand the 5x thing.  Biological filtration doesn't need that fast of water turnover.  And if you need that much flow for mechanical filtration you're probably better off addressing what ever is causing so much crud in your water.

 

I wonder where that number came from.  It might have been inappropriately borrowed from dust filtration or HVAC maybe?

[Will Billy]

There are a few ways to do this. First if you are set on a hob filter, you can optimize it. First i am a big fan of sponge pre filters on the intake. Not only does it add a bit more mechanical filtration that also prolongs the life of your hob motor, it boosts bio filtration of your bacteria, and reduces your motors ban width ever so slightly, and furthermore doesn't suck up tiny fry and the like. Aside from optimizing your cartridge compartment, you can place a cut in half pre filter sponge on the out take, or a suction cup soap dish with drain holes in it underneath the out take to displace the water flow across the surface rather than its usual undertow. 
 

if you are looking for other types of filters then yes, sponge filters are a biological filter powerhouse. They may lack in mechanical filtration compared to a hob, but it has always been my experience that a gravel vac is your primary mechanical filtration even with an hob system. You will always have to gravel vac at some point and perform water changes. Thats the primary reason why simple, cheap, reusable, easy maintenance of a sponge filter is taking over the filtration world by storm lol.
 

I am currently awaiting for a delivery of some box filters, to test out their mechanical filtration properties as they have similar flow to a sponge filter and are generally more geared towards mechanical filtration. I will post results on that soon. Somebody else might chime in on this old school technology, but until i can test it out first hand, i can neither recommend nor discourage this method as of right now. 

[JaredL]

Thanks for the replies guys. It sounds like the 5x rule is not something I should concern myself with then. Time to see how far I can turn down my canister filter.