# calculation/rule of thumb



## Bymer (Aug 22, 2008)

i have a question:

for submersible filters, what the rule of thumb in sense of liters per hour vs volume of the fish tank? :?::fish:


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## MOA (Aug 16, 2009)

Bymer said:


> i have a question:
> 
> for submersible filters, what the rule of thumb in sense of liters per hour vs volume of the fish tank? :?::fish:


Hello,

I find that L/h should be equal to about five times the volume of the tank unless the tank is small (then 2-3 times the volume of the tank will work). For example, a 100L tank should have a filter with a flow rate of about 500 L/h.

MOA


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## jones57742 (Sep 8, 2007)

Bymer said:


> for submersible filters, what the rule of thumb in sense of liters per hour vs volume of the fish tank? :?::fish:


BY:

What to you mean by submersible filter?

A typical rule of thumb is 10 times volume turnover rate per hour for the rated capacity of a filter.

IMHO filters are rated under ideal conditions but when in real world use their actual capacity is 60% to 70% of their rated capacity.

TR


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## lohachata (Jan 27, 2006)

i agree with jones..unless you have almost no fish in the tank the 10X turnover rate applies.the filtration of many of my tanks exceed that rate..


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## Bymer (Aug 22, 2008)

so if i have a 130 liter tank, then im looking at at least 1300 liters an hour?


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## Bymer (Aug 22, 2008)

The problem with my new tank(the one with blood parrots) is that they are large fish, and they are pigs, really messy eaters. im thinking of upgrading my filtration system which at this time is a submersible filter and a tetratec ex700. any suggestions?


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## jones57742 (Sep 8, 2007)

Bymer said:


> so if i have a 130 liter tank, then im looking at at least 1300 liters an hour?


Once again and please keep in mind that a filter which is rated a 1300l/hr will actually only produce approximately 800l/hr.



Bymer said:


> The problem with my new tank(the one with blood parrots) is that they are large fish, and they are pigs, really messy eaters. im thinking of upgrading my filtration system which at this time is a submersible filter and a tetratec ex700. any suggestions?


Your filter is actually what is commonly termed a cannister filter
http://www.charterhouse-aquatics.co.uk/catalog/tetratec-ex700-external-filter-p-1414.html
and is rated at 700 l/hr which implies that you are experiencing approximately 400 l/hr (app. 100 gal/hr = 3x turnover rate for your 35G tank)

An alternate would be to add another filter and fill it with biological filtration media: many members can provide suggestions for cannister filtration.

Additional Items:

1) Please remove the carbon from the existing filter as:
a) if over 28 days old it is only functioning as biological filtration; but
b) carbon in a filtration system has been hypothesized to contribute to Hole In The Head Disease in Cichlids.

2) Are you sure you want to keep two 8" fish in a 35G tank?
http://www.tropicalfishandaquariums.com/SouthAmericanCichlids/BloodParrot.asp

TR


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## Bymer (Aug 22, 2008)

would a dry/wet system perform better in this instance?


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## jones57742 (Sep 8, 2007)

Bymer said:


> would a dry/wet system perform better in this instance?


By:

IMHO a wet/dry process is superior to HOB or cannister filtration
BUT
*a wet/dry is not justified for a 35G tank.*

Typically the "break-over point" for a wet/dry system is 100 to 150 gallons.

IMHO you will be ahead (time/money/grief) to:

1) Install a 2nd cannister (or an HOB) rated at 350GPH (app 1400LPH);

2) Remove the biological filtration media from your existing cannister and place it in the new filter*;

3) Fill the remainder of the new filter with biological filtration media and;

4) Fill your existing cannister with mechanical filtration media.

TR

* A discussion of contact time is beyond the scope of a post.


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## Bymer (Aug 22, 2008)

guys, i need your advise. 

eheim 2078 or fluval fx5? for my 35gallon.


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