Originally Posted by Termato
How would you reduce water current Byron?
Depends upon the filter. I base the filter on what I need for water movement. On my small tanks i only use a simple sponge filter, connected to an air pump on the very small tanks, and on the 33g I have a little Eheim sponge filter with a motor head. Sadly Eheim stopped making these, don't know why; this is a superb little filter. But it creates very little flow, and I aim the flow into the back wall and slightly down the tank. I use the same principle with my canisters. I place the spray bar horizontally along an end wall, with the holes directed toward the glass and slightly down. You can experiment with this to get a flow down the wall and thus across the substrate, or you could have it across the surface, or into the water column.
I can illustrate the effect water flow has on fish from my 115g (5-foot) tank. On this I have a Rena XP3 canister, and because I have some fish that do need some current--namely the Spotted Driftwood Cats that must have a chunk of wood with tunnels that stands in a water current--I removed the spray bar and placed the filter return spigot about a foot in from the end wall. The water flow is directed toward the end wall, and passes over the wood. The flow hits the end wall and then disperses down the length of the tank.
I have tetra in this tank that like the neon do not occur in flowing waters, namely Hyphessobrycon bentosi, Paracheirodon axelrodi, Hemigrammus pulcher. Ever since they were introduced to this tank, these fish have consistently remained centre and right of centre, which is the side with the least water movement. They move up and out to feed, and periodically to browse around, but 95% of the day they remain out of the water movement. And this is very instructive; given the option, fish will show you their preference. I also have a group of marble hatchets, Carnegiella strigata, in this tank, about 20 of them. They very rarely venture down close to the current, but the whole group remains at the far right end of the tank, at the surface, where the water is the calmest.
We sometimes forget that fish in tanks with currents have to battle the current 24/7, they cannot rest properly, and this simply wears them down. Characins have to control their buoyancy continually, those little jerking motions; faced with moving water makes this harder too.