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-   -   Water flow question (http://www.plantedtank.net/forums/showthread.php?t=199076)

dprais1 12-02-2012 05:36 AM

Water flow question
 
How important is water flow for a planted tank?

I use a mag 5, which I estimate pumps about 350 gallons per hour for my 75 gallon tank. I also have a mag 9.5 which would more or less double the turnover.
any suggestions?

astrosag 12-02-2012 05:44 AM

For planted tanks, the main use of good flow is to ensure that CO2 and water column ferts are being distributed to all parts of the tank.

If you're not injecting CO2 or fertilizing, then flow is not nearly as important (so as long as your filter is appropriately sized for the tank).

smokaah 12-02-2012 01:36 PM

I like using a small power head regardless, seems to help with some of my algae issues. My fish like the current.

Diana 12-02-2012 05:10 PM

I usually aim for 10x from filters and power heads.
I am using the manufacturer's labeling, which we all know is over rated.
Aim the combined water movement in such a way that it is not cancelling each other out.

Actual filtration should be slower, with the water well spread out over the filter media. This benefits all the filtration we are doing.
Mechanical: If the water flows too fast it can knock the debris off the sponges and floss. Best to have a wide surface area and a deep thickness of mechanical media.
Chemical: If the water dwells among the chemical media longer it gets the benefit of either removal or addition (whichever you are doing).
Bio: Too fast water flow damages the bio film the beneficial organisms live in. They need a good flow to bring them the oxygen, ammonia and other things they need, but not too fast a flow.

Water circulation that emphasizes top to bottom circulation is most beneficial for gases that the water exchanges at the surface.
Side-to-side water movement is more natural for the fish.
Water movement across the bottom should bring the debris closer to the filter intakes (usually filter intakes are near the bottom).

dprais1 12-02-2012 05:41 PM

All my plants are doing well, even hitchhikers are are growing and doing well. I don't have an algae issue but sometimes I wonder...what could be better?

dprais1 12-02-2012 05:45 PM

Quote:

Originally Posted by Diana (Post 2096623)
I usually aim for 10x from filters and power heads.
I am using the manufacturer's labeling, which we all know is over rated.
Aim the combined water movement in such a way that it is not cancelling each other out.

Actual filtration should be slower, with the water well spread out over the filter media. This benefits all the filtration we are doing.
Mechanical: If the water flows too fast it can knock the debris off the sponges and floss. Best to have a wide surface area and a deep thickness of mechanical media.
Chemical: If the water dwells among the chemical media longer it gets the benefit of either removal or addition (whichever you are doing).
Bio: Too fast water flow damages the bio film the beneficial organisms live in. They need a good flow to bring them the oxygen, ammonia and other things they need, but not too fast a flow.

Water circulation that emphasizes top to bottom circulation is most beneficial for gases that the water exchanges at the surface.
Side-to-side water movement is more natural for the fish.
Water movement across the bottom should bring the debris closer to the filter intakes (usually filter intakes are near the bottom).


I like this answer best. As my water flow is created by my filter AND I have seen the effects on 'debris in the water' by more powerfull filtration in my tank I will keep the status quo for the time being and look in to a purely water movement feature in the future.

Thanks!

astrosag 12-05-2012 06:34 PM

As far as I know, it's been established that those are flow rates w/o filter media.

Even then, they do give you a ballpark idea. Flow isn't as critical to get exact so there's little need (from our vantage point) for that sort of specificity.

Even visually inspecting your tank for dead spots is enough of an analysis for most tanks.

Diana 12-05-2012 06:36 PM

That is why I start with the idea of 10x, but discounting for exaggerated claims, and slowing down as the filter media gets full, I probably have closer to 5x. I just never went to the bother of measuring it.
I have seen a post about someone trying that with the Aquaclear brand of power head. They got between 50-75% of the claimed flow. Then they altered the PH and got much better flow.

houseofcards 12-05-2012 06:41 PM

Personally other than the first several months I don't think flow is particularly important. Initially you need good flow to move as much as possible through the various filter medium since there is really no other filtration. Once the tank is established, most of the filtration (bio) takes place within the tank itself through the plants and substrate and other places of bio filtration. A gentle flow is all that is really required for most setups IMO.

dprais1 12-05-2012 10:10 PM

I'm guessing the really only important test for filtration efficiency is testing the water for ammonia and nitrites. I am always amazed when I see perfectly clean, clear and safe water with nothing but a large sponge filter driven by an air pump.

Water movement, maybe, should be viewed as a different aspect entirely rather than being lumped together.

Or so I am thinking...

biggerbang 12-06-2012 03:53 PM

My eheim cannister filter w/ a lily pipe has a flow rate of 105 gph. It's attached to my 20 gallon long aquarium. But it seems like there are many dead spots particularly below the output towards the middle. Where is the best place to place the input and output? I'm thinking of purchasing a small powerhead to increase circulation.

CAM6467 12-06-2012 04:11 PM

I just put one of these in my 29g yesterday. I now have virtually no true "dead" spots in the tank.

I would highly recommend spending the $30-40 (shipped) to pick on of these gems up. About the size of a typical egg, runs silently, and actually looks pretty nice in my setup.

...my $.02

STS_1OO 12-06-2012 04:41 PM

The question has to do with flow, not filtration. Unless you've seriously undersized the filter, less than heavy flow is fine. Flow is more important for dispersing anything injected into the water column to ensure that it is even.

Biggerbang - under the filter output is usually a big deadspot.

Large high-tech tanks usually need another source for increased flow. Usually this another filter bc,ironically, its easier to hide than a powerhead :D


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