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River tank water turn over?

Posted: Wed May 04, 2016 6:13 pm
by jonstfrancis
I'm setting up a new tank and wondered how often the water should be turning over through filtration.
My tank has about 75 litres (about 20 US gallons / 16 Imperial gallons).
For a tank with Sewellia lineolata how much movement of water is best for them? Lowest to highest ranges approximate?
Just looking at external cannister filters to make my river tank (not a manifold design but something with the aquarium sealed at the back to create a directional flow) work better.
What does anyone reckon?

Re: River tank water turn over?

Posted: Thu May 05, 2016 2:56 am
by Bas Pels
Once I read a definition for fast current. The water is supposed to move 1.25 meters a second. Quite likely, this was adapted from 4 feet a second (1.22 m).

After some calculations, I found this is the speed the water has in a filtertube: An Eheim 2028 pro II, moving 1000 liters an hour through 18 mm tubes sees the water going through the tubes with this speed.

Clearly, this speed is not attaninable in a tank. Putting it in other words - the more the better

Re: River tank water turn over?

Posted: Thu May 05, 2016 8:10 am
by jonstfrancis
I also thought the more the better but then questioned that. A limited space could have too much water movement especially if the water was forced out of the tank with its fishes!
So, I'm worried about too much flow but also don't wish to be disappointed with too little flow.

Re: River tank water turn over?

Posted: Thu May 05, 2016 3:34 pm
by Bas Pels
I don't think there is such a thing as too much flow for a current loving fish.

You could house it in an Eheim, and it would be happy. No way you can arrange that kind of flow in a tank

Re: River tank water turn over?

Posted: Thu May 05, 2016 7:12 pm
by jonstfrancis
So basically, any Eheim is compatible with any tank as long as too high a speed of water isn't an issue? I was wondering if the more powerful canister filters perhaps needed more water / larger tanks. If that isn't the case then I haven't any problems, I'll go with something affordable for me, yet powerful. Thanks!

Re: River tank water turn over?

Posted: Fri May 06, 2016 8:36 pm
by Diana
I would aim for 20 x the tank volume per hour. This is attainable, and not too much for the river types of fish. Start with the manufacturers ratings for filters and power heads, then add more, because the manufacturers lie.