Filter flow rate for 4ft tank

[bttay]

Planning for a new 4ft tank; I heard that some use less powerful filter for planted tank in order to minimize lost of CO2 thru filtering. Is it a correct?

With that in mind, how much flow rate is desired for a 4ft tank?

Thanks.

[loupgarou]

no, the point is to minimize surface turbulence/air exchange when co2 is on.
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you can use any type of filter as long as you keep in mind the above.

given that, overhead filters, hang on tops, trickle filters, sumps are not suggested, but if you have CO2 to burn, you can always put in more co2 to cope with the outgassing .

4ft tank: eheim 2026/2028

[chua]

I think the flowrate is about 3 times the tank volume.

[bttay]

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On 9/23/2003 2:41:15 PM

no, the point is to minimize surface turbulence/air exchange when co2 is on.
---------------------------------------
you can use any type of filter as long as you keep in mind the above.

given that, overhead filters, hang on tops, trickle filters, sumps are not suggested, but if you have CO2 to burn, you can always put in more co2 to cope with the outgassing .

4ft tank: eheim 2026/2028


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Thanks loupgarou.
Tried to find 2026 and 2028 in Eheim's website but no avail. Are they being replaced by newer models?

[vinz]

The recommended flowrate is 2 to 3 times the total water volume in an hour. That is to make sure that the water get filtered 2 to 3 times every hour.

For a 4'x2'x2', thats about 1200-800l/hr.

Filters with that capacity produce very strong currents. If you have one outlet, you'll find that it's very strong at that outlet. For my tank, I split the output to 2 ends to distribute the current out and point them to provide good circulation in the tank.

[bttay]

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Filters with that capacity produce very strong currents. If you have one outlet, you'll find that it's very strong at that outlet. For my tank, I split the output to 2 ends to distribute the current out and point them to provide good circulation in the tank.
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Vinz, you mean you do a T junction to split the flow rate? I think that is also good. Improved circulation in the tank.

[vinz]

Or a Y-junction of you can find one.

[bttay]

Thanks Vinz.

Canister filter at 1000l/h is not cheap man![]

[PeterGwee]

Get the external eheim hobby pump 1025 along with those filter housing for water coolers and you have a pretty cheap filter with large flowrate.

[bttay]

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On 9/23/2003 5:32:43 PM

Get the external eheim hobby pump 1025 along with those filter housing for water coolers and you have a pretty cheap filter with large flowrate.
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Hmm... another great idea.

[hwchoy]

actually I saw a dennerle pamphlet (Peter Chua has one) on algae and it says the recommended flowrate should be ONE time, too much filtering encourages algal growth! don't ask me why, I haven't read the pamphlet yet.

[PeterGwee]

Too many myths fly around for sometime already...phosphate causes algae is one major booboo.

[hwchoy]

I wouldn't discount it as "myth" off-hand, it is from Dennerle after all.

[bttay]

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On 9/23/2003 6:13:21 PM

actually I saw a dennerle pamphlet (Peter Chua has one) on algae and it says the recommended flowrate should be ONE time, too much filtering encourages algal growth! don't ask me why, I haven't read the pamphlet yet.
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Ya sure there are a lot of myths flying around. What I have read somewhere was that there should be enough circulation to prevent BGA. According to the article, BGA grow under low oxygen situation. Once there is good circulation, excessive oxygen should stop BGA eventually. Is this true?

[juggler]

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On 9/23/2003 2:50:57 PM

Tried to find 2026 and 2028 in Eheim's website but no avail. Are they being replaced by newer models?

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Try http://www.eheim.de
Click on Product details >> Product Guide and navigate from there.

BTW - the flow rate being 3 times the volume is just a guide. So far I only followed Eheim's website recommendation. My 470L tank uses the 2028 filter. So the flow rate is about 2 times the tank size. Probably as important is the size of the cannister/filter media to house the bacteria colony. A pump with flow rate at 3 times tank volume but no filter media is no use, right?

[geoffrey]

Probably as important is the size of the cannister/filter media to house the bacteria colony. A pump with flow rate at 3 times tank volume but no filter media is no use, right?

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Well said!

[cks]

my personal observations :
if you increase the flow rate you are not going to get the plants to photosynthesize. it does not mean that a faster flow rate will be good for your aquarium.
look at dennerle : they dont have any super big filters in their system. they have very simple filters that you only need to clean the filter media part by part. if the flow rate has to be quick and fast, dennerle would have manufactured such a filter long time ago.
imo go for a canister filter that can give your aquarium one cycle of circulation in an hour . too big / too fast a filter does not mean that it would do any good for your tank.

[geoffrey]

Photosynthesis is independent of flow rate. Light as energy to plants and photoperiod together with the necessary nutrients dictate the rate of photosynthesis.

I doubt seriously flowrate would even affect the chemical gradient of nutrients within a tank too. It only accelerate diffusion of a fresh dose of nutrients and at the end the chemical concentration within the tank eventually equilibrates.

I have the good fortune to witness a lush growth of Crypt in nature where the water flow they grew in were indeed very strong and they grew well.

[juggler]

I think there's no conclusive answer to an ideal flow rate. Different plants in nature are found growing in different conditions: stagnant, fast flowing, moderate flowing waters.

Probably the best is go for moderate flow rate (don't ask me what that means!)

I quote Diana Walstad's book "Ecology of the Planted Aquarium" pg.104.

"Moderate water movement is best

Water movement is often helpful, because it brings CO2 and other nutrients quicker and closer to the leaves. However, photosynthesis and growth may be reduced by excessively high flow rates, which induce mechanical stress for the plant and remove CO2 from the water."

The author went on to quote 2 studies where a plant grew well in slow moving water but not fast. And another vice versa.

[geoffrey]

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On 9/24/2003 12:08:29 PM

I think there's no conclusive answer to an ideal flow rate. Different plants in nature are found growing in different conditions: stagnant, fast flowing, moderate flowing waters.

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Exactly.