Overfiltering - Is It Possible?

[fergalthefish]

is it possible to over-filter a tank? for example i have a tank that is about 25litre with a filter that handles upto 45litre. is the difference too big or doesn't it matter??

 

[emmsy]

IMO NO. It is not possible. Freshwater is different to marine, where you need to keep some nutrients in the water. With freshwater, the more crap you can filter out the better. I have 2x fluval 405's in my 6x2x2 and that is seriously overfiltering, and no probs at all

Emma

 

[Lateral Line]

It is very possible to over filter, it depends on your definitions.

Adding more filters then necessary will not remove more waste then is present. If you have "x" waste and "x" bacteria capacity then adding more filters means you have the same "x" bacteria capacity distributed over several units. In a big tank, running 2 small filters is generally better then 1 large as if the large fails, you've lost the lot.

In planted tanks, particularly hi-tech setups, the surface agitation created by excess filtration loses you any benefits you may have from CO2 injection, it gets knocked out of solution before the plants can use it.

Many common trops come from quiet backwater environments. Excessive water movement is alien to them and leads to a constant level of stress - this invariably shortens the fishes life.

 

[emmsy]

i agree with the 2 small filter part for sure.There are of course extremes to every situation

emma

 

[Tech-Frog]

I think it is possible, but only in extremes, for instance you take so many nitrates ect. out of the water, that there is nothing left for the bacteria to 'eat' and therefore they 'starve' and then making you have to recycle.
(This is just my opinion and is probaly wrong. )

 

[andywg]

It all depends on what you class as "filtering". Once you deduct the filtration process from the pump turnover process then it would appear very hard to over filter, you will just get a more thinly spread bacteria colony (as noted by LL). The issue when thinking of adding a number of filters is that of excessive turnover. While some fish can handle large turnover rates (some marine tanks run at over 100x the tank's volume turned over every hour) others will not appreciate such vigourous water movement.

 

[waterdrop]

LL and andywg always have such great answers! Separating the pure concept of filtration from the concept of water turnover really does help one think about it! Thx!

Makes me think of a trip a while back when I was standing next to a huge open marsh area in the Okefenokee Swamp in Georgia. I looked down a saw a small fish the size of a minnow. Looking out I realized that little fish had acres and acres and acres of fresh filtration working for him, a billion times over a small aquarium filter.. and yet he was sitting perfectly still in crystal clear still water, no turbulence or turnover to disturb the peace of his little space.. or the silence of the air or beauty of the setting sun for me, for that matter. I sighed and hoped he would stay clear of the alligator next to him.

~~waterdrop~~

 

[doresy]

and yet he was sitting perfectly still in crystal clear still water, no turbulence or turnover to disturb the peace of his little space.. or the silence of the air or beauty of the setting sun for me, for that matter. I sighed and hoped he would stay clear of the alligator next to him.

~~waterdrop~~

I closed my eyes and I was almost there then a vision of an old supermarket trolley spoilt it

 

[jgray152]

I have 2x fluval 405's in my 6x2x2 and that is seriously overfiltering, and no probs at all

I don't think so. It depends on what fish you have in your tank. The 405 is documented at 225 GPH which lets says its at 70% of what is documented where 10% is marketing and 10% is the design fault so thats 157 GPH in reality. About 300 GPH for filtration is about 2 cycles per hour for your 180 US Gal tank. Not very high at all. Depending on the fish load you have you should be near 5 cycles per hour minimum.

The only way you can over filter (For Freshwater) is by having to much current in the water. Other than that its up to you. The more surface are you have the more time you have between cleanings.

 

[waterdrop]

and yet he was sitting perfectly still in crystal clear still water, no turbulence or turnover to disturb the peace of his little space.. or the silence of the air or beauty of the setting sun for me, for that matter. I sighed and hoped he would stay clear of the alligator next to him.

~~waterdrop~~

I closed my eyes and I was almost there then a vision of an old supermarket trolley spoilt it

If you ever get to San Francisco doresy, ride the trolleys. They've got some good ones.

 

[JoshuaA]

I'm going to be putting a Fluval 205 on a 60 Litre tank... keep in mind that the 60 litres will be more like 40 once the multiple layers of substrate are in and the fact I won't be filling to the top. In theory that will be at least 10x turnover but I know Hagen are remarkably generous with ratings and it will be more like 4/5x turnover.

However I believe circulation and turnover cannot be over done in my eyes, though Flow can be. Having too much flow coming out the pipes will be stressful but there is no problem in having good gentle yet effective circulation.

I have a 1400lh filter on my Rio 125 as well as a Korlina Nano powerhead and even then I think the tank could do with a bit more flow!

 

[OldMan47]

Excessive turnover rate filter. Note the developing sand dunes and the suspended sand.

Same tank the next day with a properly sized filter on it.

Enough said?

 

[JoshuaA]

What sort of turnover was that filter doing on that small tank with sand though? I find External filters have been a lot more "forgiving" than internals when you ramp up the flow up to 10x.

I'm yet to experience a sand storm quite like that or anything near to that.

 

[hillmar77]

I'm sure sticking a FX5 in a 30 gallon tank would cause a little typhoon or a eheim 2260 would cause a tornado and a hurricane at the same time
Check out this nuclear power plant
http/ezinearticles.com/?How-About-the-Eheim-2260-Canister-Filter-For-Your-Aquarium?&id=4383283

 

[OldMan47]

Joshua, that filter is really a sponge filter being powered by a power head meant for a 50 gallon tank at about 4x. On a simple 20 gallon, it is obvious to me that the resulting 10x (+/-) was simply too much. I have seen lots of people saying that 10x is ideal, so I had decided to give it a try. It didn't take long for me to change my mind though. I have some tanks that merely have an air driven sponge filter that do great and any truly high flow arrangements have always given me about the same result as that power head combo. The tiny filter that replaced the AC50 power head was rated for a 20 gallon maximum tank. In most cases the tank size ratings are close to 3x or 4x, so the one that cleared the tank was much smaller but still an external with the typical tubes to remove and return water. I don't happen to care much for that particular filter so I will not mention its name here. Some people may find it perfect for their specific needs after all.