Can one over-filter?

Is there such a thing as over-filtration. Lets say you have a 100l tank and hook up a 1500l/h filter, will you just have super clear water or are there any side effects?:wondering:

 

No you cant over filtrate but you will create a whirlpool in the tank...

 

Will that be a internal or external filter?? Just add a spray bar the the water going back into the water so you not making the whirlpool stream effect.

 

side effects to over filtering may result in fish drowning (Whilpool effect), sand being sucked up the filter, sand blasting to the glass and fish, more noise & electricity...

 

Ja, your filtration will ultimately be majority biological, and the bacteria will only survive in a colony as large as the food source can support. I've seen in one of my tanks that my ceramic noodles have gone from brown to light brown after I removed a whole lot of fish, so I'm assuming that means the bacteria colony got smaller as the bioload decreased...

 

i would say its always better to have more then one filter so that when u clean one the other can still try to keep up with the bio load, as for over filter as the guys said the biggest worry would be the amount of current in the tank most of the fish dont like heavy currents, unless you getting some hillstream loaches of course

 

You can over filter. In my opinion anyway. If you have a 100L tank, your most effective amount of water through a filter is between 5 and 6 times the tank volume every hour. Anything more than that and you will be creating too much flow in the tank.

Also, there is a recommended rate of water flow through a filtration device. A high speed filter will create an aerobic bacteria colony. This means that the bacteria still need Oxygen to do their jobs properly. A slower rate through the filter will create Anaerobic bacteria, which from what I have heard and read, are even better than the aerobic bacteria. I have a special filter chamber waiting in the wings to try my hand at an anaerobic filter device, I just need to stop procrastinating and do it. I'm also just wanting to do some more research on the subject, but I believe the professor is an expert on this matter.

Besides all of this, there is the fact that someone mentioned earlier: The bacteria will only colonize enough to control the environment as it is in the tank. IE: If the fish load drops, the bacteria colonies will also die off slightly. The amount of waste in the tank will decide how big a bacteria colony you will have. No more, or no less... Except when starting up the tank.

I do still believe that you should have a lot of surface area to enable the maximum size bacterial colony your tank can support. I must admit, this is the reason I like sump filtration. I find it more economical than a canister filter, and more efficient. But I guess both have their advantages and disadvantages.

 

i go with yes you can and the best rate would be as slagter has said is turn your tanks volume over 5 to 6 times a hour.

 

I disagree with that. Surely the slower the water moves over the bacteria, the more effective the bacteria will be at removing the toxic waste from the water?

Obviously not too slow...

 

You guys are confusing flow rate and filtration area

Can you overfilter - No
Can you have too high a flow rate - Yes

Think of having a 2000lph canister on 1ft tank. The canister is still doing its job and is specced correctly for total filter area, the flow coming out of the outlet would cause some serious turbulence in the tank

Similarly think in terms of a sump and display tank. Say 6ft tank with a 6ft sump. The flow rate into the display is set by the return pump. The same pump could be used if you changed the sump to a 3ft, its just the filter area that's being reduced

 

Consider this:
If the flow was slower, it would just mean a lower bacteria population in your filter. Also it would mean that your water would be filtered less efficiently Via the filter.
Because the max amount of bacteria that can populate your filter is limited by the amount of food and oxygen available at any given time. With a slower flow rate both of those will be lower. Also, yes you'd eliminate more waste in the water, But remember that instead of removing 100% of NH3 and NO2 per l per 30sec, they could remove 80% in 5 sec at A Higher flow rate; so in the overall the higher flow rate would allow for better filtration of the entire tank.(those were just example numbers by the way).

But obviously then your flow rate is limited by what it will do to the actual water movement in the tank.

 

ok so if I have this right.. what you guys are saying is if I have a 6ft tank with 3ft sump and I use a 200lt/h pump it should filter fine and not course any problems with water flow, I could use the exact same setup except the tank is now 3ft with a 3ft sump and a 200lt/h pump and I add a spay bar onto the pump it should work 100% right because it is filtering at 10times per hour but the water would have no serious turbulence.
Is this right?

 

depending on were they come from I suppose :smile1:

 

Erm... No.

A 3ft tank is 100L (standard size). So you have 200L of water in total if you have a 3ft sump. A 200L/h pump will only filter your total tank water once every hour. You'd need a 2000L/h pump to filter all that water 10X an hour... So your tank will be under filtered.

I see where all of the others are coming from...

 

Guys, can I point out a flaw in your arguements here.

Let's say hypothetically you have a 10 litre tank. You therefore need a 60-100 litre per house filter pump... this will turn over your 10 litres 6 to 10 times.

In a 20 litre tank yoy would need a 120-200 litre per hour pump to give you the same ratio filtration, i.e 6-10 times per hour.

The 120-200litre pump pumps at EXACTLY the same flow rate if you put it into the 20litre OR the 10 litre tank.. meaning that the same FLOW RATE will pass over the bacteria.

So by putting the larger pump into the smaller tank will make absolutely NO DIFFERENCE on the bacteria because it is suitable for the big tank, thus also suitable for the small tank.

The problems come into being that with a higher flow-rate, the pump is stronger, thus the water coming OUT the pump will be pumping possible a little hard, creating unnecessary currents in the tank. This can be dialed down by most good quality pumps, or distributed better over the water through a spray-bar.

Now everyone is going to tell me that because the water is pumping a lot more water per-hour, then there won't be enough oxygen in the water for the bacterial... bollocks!

Your bacteria colony will only establish to a population necessary for your tank. Obviously whether you have the smaller pump or the larger pump, you would have aerated your water in anycase. So the SAME amount of bacteria population will live in the small filter as the big filter.

Yes you will be turning over more water per hour... but this will not necessarily mean better filtration, as your bacteria population will still be at the same size as if it were in a small filter.

So you could have 1 million bacteria in your small filter, turning the water over at 10 timers per hour. You would still only have 1 million bacteria in your larger filter because your waste and food from the fish is still the same.

Does the water pass through the filter too fast for the 1 million bacteria to get sufficient food & oxygen... Well DUH, NO... because if the larger filter was in the larger tank it would work... even at a "higher flow rate".

If the filter is designed for filtering for aquariums, then you can use it... the larger filter might be able to house 50 million bacteria, but if you only need 1 million, only 1 million will colonize.

So NO, according to my logic, you CAN'T overfilter just by going with a bigger than necessary pump. You will however create excess currents in your tank, which could stress out the fish. You will also have a higher than necessary electricity bill, and would have had to pay for a more expensive pump.