Over Filtration?

FishinFool

Hey I was just wondering if there is such a thing as over filtration for a freshwater tank. I have a 20 gallon tank and am about to purchase a canister filter for it (fluval 105 which is rated for a 25 gallon tank). But the 205 is only like 10 or 20 dollars more but has almost double the filtration and is rated for a 40 gallon tank. Could the extra filtration be bad in anyway for the tank, like too much flow? Thanks for your help

Eddie1KRR

Great post/question.
I'm new here and although I have done a TON of reading and taken way to many written notes, I can't reply with much experience. My reply is more of a piggy back on your question. I hope you don't mind.
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I worry about the same, but from what I read so far, it's not possible to over filter (someone please correct me if I'm wrong) the bigger concern is the output of the filter making a washing machine out of the tank (and my own paranoia that I'm going to suck small fish in the intake) Mine is far overrated as well, after cycling the tank, everything seems ok so far except 2 things.

1st being a hvac/mechanical guy, it kinda makes sense to me that the resistance of chocking it off like I have it, is going to shorten the life of the motor via resistance, since Im not slowing down the motor, just the flow, so the motor is working much harder against that resistance.
2nd is, even half or 3/4 choked off, the current across the top is still really strong, it's strange to me watching the top feeding fish eat while fighting the current...But I guess no one got hurt so far, and they all are eating so I'm ok?

I can shut it down further, as you could/can but I have no bubblers of any kind at the bottom, so I'm relying on the output to give me some of that thru waterfall effect without power washing the fish.

Looking forward to the replies!

AbbeysDad

First let me say that good tank maintenance and routine weekly water changes are your very best 'filters'.
As for power filters, good filtration is really not about how much or how fast the water flows through the filter media. Actually it's almost the opposite as the best filtration happens when water moves [more] slowly through very fine media.
Unless you're trying to create a raging river, many fish will not appreciate excessive flow in the tank as they have to constantly swim hard to even stay still.
Also, as the other poster mentions, without a bypass, throttling back the flow on many filters creates a fair amount of back pressure and potential excessive load on the pump motor. (This may be less of an issue with magnetic induction impellers).
In any event, I'd suggest you go with the filter designed for the size of your tank, because most often, more is less.

j dizzel

Agreed. Size filter no more than one tank size up. If you want current use a power head and under gravel filter. Filtering has come along way. When hang on back ( bio wheels ) first hit the market they impacted the aquarium world by storm. Used them like crazy. Recently got back into the hobby and went straight back to the bio wheels because of their success. Started breeding so suction was an issue. Researched and began using sponge filter by ( ati hydro ). Wow these are great, inexpensive, water clearing, bacteria laden machines that can't be over sized. Just clean them in used tank water during water changes and your good to go. I have 2 120 gallon capibility sponge filters in my 45 gallon breeding tank.

Byron

Very good issues have been mentioned in the last two posts. Filtration is something that should be geared to the specific needs of the aquarium, and not all aquaria are the same. Live plants have a major impact, as does not only the number of fish but the species of fish. Then there are the two quite different but obviously related issues of actual filtering and water flow. Exceeding the needs of the fish and the entire ecological/biological system with either too much filtration or too much water flow can be very detrimental to the fish.

Byron.

FishinFool

Awesome, thanks for the insight guys, for my 20 gallon tank I went with the Fluval 106 which is rated for a 25 gallons so hopefully it will work well

beetlebz

There are ways to "fix" the filters output in either direction based on the specific needs of the aquarium. I have around 7-800 gph going through my 110g, but trust me, severums can be SLOBS!

Increasing filtration on a tank that can not handle the increase in flow rates, can be as simple as using a bigger filter with a diffuser, such as a spray bar, you can even get creative and use multiple spray bars with some parts and ingenuity. In most any pump, restricting the flow on either the suction or discharge side will cause some major issues, and will likely not solve the problem. The 4 feet of hose between the pump and the discharge isnt really long enough to translate high pressure (from the partially closed valve) to lower flow completely.

everyone above really hit alot of nails right on the head, so I suspect im posting based on my need to type excessively. At any rate, my point is I think you will be happy with the 106 :) I found early on that over filtration is no substitute for patience and cleanliness!

Ridewithme38

I have a TopFin 30 Filter, a AquaClear 500(110), a 4" 20ppm Sponge filter and a 3" 40ppm Sponge filter on my 29 Gallon tank...

Are you guys saying i might be over filtering?

Byron

Probably, big time. But, filtration depends upon the needs of the fish (thinking water movement here) and the tank's biology, so we need to know what fish are in the tank (species and numbers), if live plants are present, and snails.

Ridewithme38

Ahh, see thats the rub...I have a Black Moor a RedCap Oranda and a Common Goldfish, No live plants and (am waiting on) a dozen Malysian Trumpet snails (to come in the mail)