Filtration vs. Overfiltration

[RufusT]

I was wondering if you (that's plural) could give me your arguments for excessive filtration some of the people here are using. I'm hearing of 10x or 15x the aquarium volume per hour. This is in stark contrast to the producers' suggestions, which rarely exceed 3-4x (take Eheim's 1050lph for aquariums of up to 350l).

What is the point of overfiltration? Beter ferts distribution? That could be achieved through a simple circulation pump. Better NH4 transformation into NO3 by the nitrifying bacteria in the filter? Well, the difference between 10x and 4x the volume per hour is in NH4 (from feces etc.) getting into the filter within 5 or, say, 15 minutes since it appears in the water column. Or is it about water column detritus particles filtration?

Has any one seen any major difference between 3-4x and 10-15x filtration? That concerns algae presence, water purity, fish behaviour etc.

 

[nipat]

I started with 2-3x turnover. That was I “wanted to believe” because it's cheaper.
So I opted to DIY sump with 2.4x turnover. But debris was just flowing around or
sticking to plant leaves.

Now my tank has about 10x “real” turnover (Eheim 2217 has real output about 760L/hr
with spray bar attached—my tank is 80L). I've found the current was definitely too strong,
so I turned the spray bar to push water to the glass wall which gave the result I liked.
No debris problem anymore. Black Neons seem happier.

I don't know how manufacturers calculate their tank size vs filter models ratings.
May be from the marketings who want to give their products a good impression.

Opinions on forums are varied. Some says 10x from the manufacturers' ratings,
some says 5-7x from real output of the filter. The way you place things in the tank,
plant biomass, animal load affect this issue too (of course).

 

[Philosophos]

It's not too hard to understand once you've kept a densely planted tank with CO2 demanding plants. Dead flow means no CO2, which means deterioration lower down.

Besides that, plants leave their own waste when leaves are shed or trimmed and not removed from the tank by accident. This means NH4 leeching into the water, and the best way to prevent buildup is to suck it into a canister filter then to give it a monthly cleaning.

You can do lower filtration levels in more open tanks; that's definitely an option. I've got some low tech tanks that are medium to dense in their planting and they're doing great because the plants are simple and undemanding.

Higher values of light will definitely increase the need for higher filtration through CO2 demands.

-Philosophos

 

[shoggoth43]

Mechanical filtration is one thing the turnover will get you. It may help with chemical if you bother with it but if you go too high you lose effective ab/adsorbtion. Biological may or may not be affected.

From a behavior standpoint the fish will definitely change. The sluggish streams may not induce the "proper" behavior of the fish and exercise of the fish is never a bad thing. My neons and such have improved their "out and about" a bit since I added a koralia nano but overall the cube still has a pretty sedate flow. Bear in mind that you're still typically looking at far less flow in the tank than you are in the wild. 1mph is still 18" per SECOND so for my cube I'd need something that can do ~20-30 Gallons every second with laminar flow. Not going to happen...

The best you'll get is a couple areas of flow where there's a "proper" amount of flow and lots of areas where the fish can rest. Pretty much what happens out in most river systems. This will get the fish moving and then resting as they get tired. I notice my discus actively swimming against the flow of new water going into the tank but otherwise they're just hanging out not doing much of anything.

You also will run into lots of places where the flow just doesn't seem to penetrate. Mad amounts of flow will deal with that, but otherwise there's just no easy way to get your ferts and especially the CO2 into these places without a lot of forethought and/or infrastructure.

I suspect those are the primary reasons for overkill on the turnovers.

-
S

I was wondering if you (that's plural) could give me your arguments for excessive filtration some of the people here are using. I'm hearing of 10x or 15x the aquarium volume per hour. This is in stark contrast to the producers' suggestions, which rarely exceed 3-4x (take Eheim's 1050lph for aquariums of up to 350l).

What is the point of overfiltration? Beter ferts distribution? That could be achieved through a simple circulation pump. Better NH4 transformation into NO3 by the nitrifying bacteria in the filter? Well, the difference between 10x and 4x the volume per hour is in NH4 (from feces etc.) getting into the filter within 5 or, say, 15 minutes since it appears in the water column. Or is it about water column detritus particles filtration?

Has any one seen any major difference between 3-4x and 10-15x filtration? That concerns algae presence, water purity, fish behaviour etc.

 

[The Rockster]

Eliminating Possible Filtration Problems

This my question as well.................How much filtration for a planted tank?

I have been in several lfs, and they have 70- 100 gallon tanks full of plants, with one cannister filter. They claim that the plants are the BEST source of filtration, and that in a heavily planted tank, you don't need 10 X 20 times the volume of the tank. Of course there are mediating factors, like bio load, plant mass etc.

And then of course powerheads can be added for increased circulation, which also has its own 10-20 X tank volume rule of thumb, which is downplayed by many as not being required..............and lots of show tanks don't adhere to this equation.

I guess, if you have a stable tank, and are happy with its condition, keep doing what your doing, regardless of suggested guide lines.
But if your combating algae, fish kills, or other issues, the guide lines are one way of removing a possible cause.

 

[shoggoth43]

Most of the time the high flow seems to be to get CO2 where it needs to be.

For reefers, I've seen systems where there is maybe a couple of turnovers an hour at best for the bio filtration and sometimes only 1 turnover an hour for refugiums. All the rest of the flow is recirc lines and/or Koralias. A lot of it depends on what you're up to and why. I've also seen massive turnovers to the sump and not much to the bio in the sump. I've seen massive turnovers to the biotower/cannister feeding to a sump that only gets a couple tank turnovers and hour.

If you just want biofiltration you don't need insaneflow. If you need to get stuff to places then you need flow, but not necessarily filtration. A Koralia in the tank is certainly less wasteful of electricity vs. dropping to a sump under the tank and pumping 1500GPH back up against 4-5 feet of head. If you don't use a sump, a pump for 1500GPH in a cannister config can be much more efficient depending on what you're driving against. Neither of these can be called efficient if all you need is a 35W eheim filter to do what you need. OTOH, a 300$ pump will likely outlast a couple of 40$ Koralia and can usually outdrive them.

So, I guess it really comes down to how crammed is your tank and how many fish are in there....

-
S

This my question as well.................How much filtration for a planted tank?

I have been in several lfs, and they have 70- 100 gallon tanks full of plants, with one cannister filter. They claim that the plants are the BEST source of filtration, and that in a heavily planted tank, you don't need 10 X 20 times the volume of the tank. Of course there are mediating factors, like bio load, plant mass etc.

And then of course powerheads can be added for increased circulation, which also has its own 10-20 X tank volume rule of thumb, which is downplayed by many as not being required..............and lots of show tanks don't adhere to this equation.

I guess, if you have a stable tank, and are happy with its condition, keep doing what your doing, regardless of suggested guide lines.
But if your combating algae, fish kills, or other issues, the guide lines are one way of removing a possible cause.

 

[Biollante]

My Unworthy Opinion

Hi All,

As unworthy as my opinion may be, I am of the view that there is no such thing as too much filtration, I am sure there is a practical limit, I have not found that limit.

shoggoth43 that terrible, indescribable thing vaster than any subway train – shapeless congeries of protoplasmic bubbles, makes an excellent point regarding water flow. I think it nearly impossible for people understand just how much water flow (water change?) exist in even slow moving bodies of water.

shoggoth43, faintly self-luminous and with myriads of temporary eyes has noted that most fish are in fact healthier and happier with water movement.

shoggoth43 forming and un-forming as pustules of greenish light all over notes Hydor Koralia boosts the (I think he meant) linear flow, laminar flow is a problem the Hydor Koralia helps overcome, decreasing the dead spots.

shoggoth43, the tunnel-filling front that bore down upon us, crushing the frantic penguins and slithering over the glistening floor that it and its kind had swept so evilly free of all litter is concerned that the chemical filtration might not be able adsorb the waste material. This killer of poor innocent frantic penguins, need not worry the various materials used are capable of adsorbing or ion exchange, as the case may be, from incredibly high velocity water.

Once upon a time, we did not believe in water movement in general. Then as we evolved the water turnover increased. As our friends in the marine and in particular the reef keepers demonstrated improved filtration and health of critters with what at the time seemed like astronomical flow rates.

I know folks that use 25 micron filter bags on the output, catches the big pieces, simple mechanical filtration.

In well-planted tanks, a trend around here is the use of pumps with filter bags on the output. I don’t know if there is a rationale for the use of 25-micron bags, if they are just available, or it is what everyone else is doing.

Personally, I like mechanical and biological filtration. I like 15 to 20 turns of tank volume per hour. I think I can say that most fish do better with higher flow rates, might be exceptions such as Beta’s which need still areas to breed and live in mud-puddles in the wild.

Most plants as long as they are not being damaged by the flow seem to do better at higher flow rates, CO2, nutrient availability and waste removal are improved.

My apologies to Howard P Lovecraft and his fans.

Biollante


“It was a terrible, indescribable thing vaster than any subway train – a shapeless congeries of protoplasmic bubbles, faintly self-luminous, and with myriads of temporary eyes forming and un-forming as pustules of greenish light all over the tunnel-filling front that bore down upon us, crushing the frantic penguins and slithering over the glistening floor that it and its kind had swept so evilly free of all litter.” — H. P. Lovecraft, At The Mountains of Madness


Edit:spelling "absorbing" when I meant "adsorbing". Added Italics At The Mountains of Madness.