# What is the flow & turnover



## Zak Rafik (6 Mar 2015)

I'm constantly being confused by the terms "flow" & "turnover" for a planted tank.
Can some kind sole explain in a easy to understand manner.
Thanks.


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## Colinlp (6 Mar 2015)

Flow will be the total movement of water within the tank and turnover the total water movement through the filter/sump. Well that's how it works in marine tanks anyway


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## Edvet (6 Mar 2015)

As i see it: turnover: amount of times the tankvolume goes through a filter (canister or sump); Flow: movement of water through the tank ( through filter pumps and circulation pumps)
My tank goes thorought the filter app 2 times /hour (2 times turnover), with circulationpumps i had a flow of app 20000 liter.


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## EnderUK (6 Mar 2015)

Flow is the movement of a fluid or gas.
Turn over is your flow rate.

They kind of get mixed up in this hobby.


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## ian_m (6 Mar 2015)

Flow is measured in litres/second, pints/hour, gallons/minute, bushels per fortnight  ie volume per time.

Turnover is number of times tank volume is cycled per unit time. ie a 200 litre per hour filter will turnover a 100 litre tanks 2 times an hour.


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## Rahms (6 Mar 2015)

"low flow" can be discussed qualitatively, in that it doesn't only mean "low turnover". You can pump 20x turnover in to a tank, but if its set up poorly there will be some areas that don't see much movement. Imagine a powerhead blasting straight at a large rock- high turnover but poor flow.


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## EnderUK (6 Mar 2015)

ian_m said:


> Flow is measured in litres/second, pints/hour, gallons/minute, bushels per fortnight  ie volume per time.
> 
> Turnover is number of times tank volume is cycled per unit time. ie a 200 litre per hour filter will turnover a 100 litre tanks 2 times an hour.



Those two examples are the same thing, flowrate or the measure of flow per time unit. Flow isn't really quantitative, it's more to do with the type of movement, such as laminar and turbulent etc.

Flow in your tank would be very difficult to measure, there's movement or flow everywhere depending on your setup. You can measure the flow rate going in and out of your tank if you know how much water is going through an internal/external filter or power head though, the internal and power heads would be more difficult to quantify. This movement through the filter or powerhead would be your turn over of water ie 10 tanks of water per hour or the flow rate of x Liter or Kg of water per minute/second/hour/day etc.


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## NC10 (6 Mar 2015)

ian_m said:


> bushels per fortnight



You missed megalitres per decade 



Zak Rafik said:


> Can some kind sole explain in a easy to understand manner.
> .



I agree entirely with the others who say turnover is what you have going through the filter/sump. Your flow is everything else you have in the tank, powerheads etc not forgetting the return from the filter itself.

This may not be technically or scientifically correct, but it's what most people go with within this hobby.


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