Water flow and bubbles

[Negseven]

Hi, have got my tank setup (33 gallon and Fluval U3 filter) All I have in tank is plants at the moment. I can see gentle water flow around plants ok, but do I need to put the Venturi device on top of the upper filter outlet to introduce oxygen into the tank (I haven’t got it attached yet)?

 

[Guyb93]

Best way I know of getting oxygen into the water is by surface movement , as long as the water surface is moving you should get oxygen exchanges , plants themselves also adds O2 , I have very little experience with internal filters But the Venturi will allow O2 to mix with the water but I wouldn’t rely on that 100% personally

 

[kiko]

yes and no...these new filter types or as some call it...the freshwater skimmers
will take in the water and add a mix of air which will cause the bubbles to break apart the film in the surface...
you have some pumps better than this u3 for that effect
you have to keep in mind if you do have floating plants they're a goner
as for the biofilm...you can add more flow and that usually goes away...
or an overflow into your filtration be it hob/sump/canister will usually get rid of it with very minimal flow
if you do want to keep floating plants...the u3 should be fine...just increase the water movement...also keep in mind...
more movement = more algae
So don't go crazy

 

[Byron]

I used a very similar filter in two tanks. I placed the filter in one of the rear corners at the surface, so the flow from the filter created ripples in that area. That is the gas exchange issue solved. Current down the tank is an important issue for fish, as some need more, while others need almost none. Aiming the flow down the back wall of the tank provided very little flow across the front. Plants should not be swaying, that is likely too strong for quiet water fish (depends what species of fish you have).