# How much water flow is enough?



## Django (Jun 13, 2012)

I have a 10 gal. low tech tank and I thought there was too much flow so I turned the Fluval U2 down. Now I'm thinking maybe the flow is too low.

I can guesstimate gallons per hour with the filter. Could I get opinions including gallons per hour?

Thanks.


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## rebelbuck1993 (Sep 3, 2014)

It really depends on what you have for bio load and how many plants and what type they are my mid plant heavy stocked 40b i have a 350gph flow, real frow(from the outlet) and it is good but on my 75 i have heavy planted and low bio load with a eheim 2215 and it is just fine high light, co2, and dry fert on black diamond sand.


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## RoseTyler (Oct 27, 2014)

I always overstock my tanks, planted or not. My rule of thumb has always been a filter 2x as strong as what is recommended. Right now I have a filter which flows at 400g/hour.


I had a 200g/hour filter on it just earlier this week but my fish were stressed and my tetras had lost their color, so I decided to just go back to my tried and true method and everything looks great.


I have a low light/low tech tank.


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## Diana (Jan 14, 2010)

Water surface should be gently rippling. 
Plants should be gently waving through most of the tank. Right in front of the filter (even low flow) might be too much for the plants. 

10x is high flow for a planted tank, but not too bad for most community fish. 10 gallon tank would need 100 gph with filters, power heads or a combination. Most of the cheap HOB filters are poor enough at filtering that they need to be figured at this rate to do their job. 

20x is a Hillstream Loach tank. Only small, sturdy plants. 

5x is medium flow. Canister filters and Aquaclears are efficient enough to do a good job at this rate, and it is more in line with what the plants need. 

If you are using a combination of filters and power heads to get the flow this can work well. The volume of filter media is probably smaller, so give it more attention to cleaning until you figure out how things are going. A filter that does most of the work and a small power head aimed at a dead spot could be the best arrangement.


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## Django (Jun 13, 2012)

Thank you all for helpful feedback. I think it is the x-factor that I can guess at from how strong the flow is. I adjusted the filter when I got home to something like 5x to 6x for my 10 gal.

The U2 is an internal filter rated at 30 gal. tank max - 105 gph, or 3.5x for a 30. I'm using the middle output which is lower in the water and divides the output into some lines of holes - a little slower than the top, intended for planted tanks - but I have to keep it on very low.

I only have the two sponges (pretty thin, too) in the filter, but there's all kinds of gunk in there every week. Pic below, most of the fish are sleeping


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## Diana (Jan 14, 2010)

Never believe what size the manufacturer says the filter is good for.


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## Mariostg (Sep 6, 2014)

Diana said:


> Water surface should be gently rippling.
> Plants should be gently waving through most of the tank. Right in front of the filter (even low flow) might be too much for the plants.
> 
> 10x is high flow for a planted tank, but not too bad for most community fish. 10 gallon tank would need 100 gph with filters, power heads or a combination. Most of the cheap HOB filters are poor enough at filtering that they need to be figured at this rate to do their job.
> ...


I really like this guideline. Never measure the real flow rate of my Eheims, but the water surfaces ripple  Plants don't really wave but I can see "dirt" moving like in a gentle stream.


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