Venturi, airstones or both??

[awfireman]

Hello,

I am building a new 45 gallon aquarium. I am going to the the Fluval U4 for filtration and it has the option for venturi for oxygenation. Should I use the venturi or go with a traditional air-pump and airstone, or use both? Does using the venturi create additional noise? Also, one the Fluval U4 shich setting should I use? Top, spray bar, or bottom outlet? It has options for all three. This will be a cichlid tank but will also be home to a very small painter turtle my daughters found until it can be released into the wild on our pond we live on.
Thanks so much for any advice.
-Aaron

 

[Bruce Leyland-Jones]

Bubbles make noise.
Bubbles from an air pump can often be minimised by reducing the outflow from the pump. (Cheaper models don't have this capacity, but air flow can still be reduced if you fit plastic control valves into the pipes).
The venturi will be noisier still and, unless you can reduce your filter's output, you can't reduce the bubble flow and subsequent bubbly noise.

Personally, I got used to the noise and, if it all went quiet, then it was a good and clear warning that something might be amiss with one piece of equipment or another.

The other consideration you need is your tank inhabitants. Some fresh thrive in noisy, fast-flowing tanks, others thrive in a quiet, sedate tank, whilst others seem not to give a monkey's either way. (I'm guessing one of the many tropical downpours they'd have 'back home' would be on the noisy side, with sudden floods being a normal feature).

But then...what do I know?

 

[Essjay]

Provided the filter circulates the water adequately and moves water along the tank just under the surface, you don't need bubbled for oxygenation. All bubbles to is churn the water up so that more 'underneath' water reaches the surface. A filter with a well positioned outlet is just as effective.

 

[Ichthys]

As Essjay said, a well positioned filter outlet that pushes the water across the surface is all you needunless the tank is very heavily stocked.
Also venturis are a bit of a gimmick. Somebody made one, and people think bubbles mean good aeration so it sold, so all the others had to follow suit. They don’t provide much aeration.

 

[awfireman]

Provided the filter circulates the water adequately and moves water along the tank just under the surface, you don't need bubbled for oxygenation. All bubbles to is churn the water up so that more 'underneath' water reaches the surface. A filter with a well positioned outlet is just as effective.

What depth would be a well "positioned outlet"

Also, as I stated above, I want to stock the tank with African Cichlids but not sure what species to get. The tank if fairly tall (29"H) and I want the fish to inhabit all levels of the tank. I know most Africans like the bottom third so what combos of Africans would I need to accomplish having fish at all levels of the tank. Sorry for so many questions, I just want to make sure I am doing this correctly, for myself and the fish that will live in the tank. I also dont want to overstock so how many fish for a 45g that is 36x12.5x29

 

[Boundava]

Hello,

I am building a new 45 gallon aquarium. I am going to the the Fluval U4 for filtration and it has the option for venturi for oxygenation. Should I use the venturi or go with a traditional air-pump and airstone, or use both? Does using the venturi create additional noise? Also, one the Fluval U4 shich setting should I use? Top, spray bar, or bottom outlet? It has options for all three. This will be a cichlid tank but will also be home to a very small painter turtle my daughters found until it can be released into the wild on our pond we live on.
Thanks so much for any advice.
-Aaron

I have the U3 and the venturi didn't work too well for me I have mine horizontal withe the top nozzle. The spraybar was a bit weak for me. If you are going to have a turtle you may need extra filtration. I would probably go with a HOB, probably the Tidal 55. I replaced the carbon insert with a piece of sponge. I don't need the carbon and don't ever use disposable filter media.

 

[Essjay]

A well positioned outlet is one that creates a rippling effect on the surface. It doesn't matter where in the tank the fish live, what matters is gas exchange at the surface - oxygen in and carbon dioxide out. If the filter pushes water across the top, it reaches the other side of the tank and goes downwards, then travels across the bottom of the tank to the filter side, then up through the filter and across the top again. It's this movement bringing water from low down in the tank to the surface which ensures better gas exchange. All bubbles do, whether from a venturi or airstone, is churn the water bring lower down water to the surface - but a filter does that anyway.

 

[Bruce Leyland-Jones]

...All bubbles do, whether from a venturi or airstone, is churn the water bring lower down water to the surface - but a filter does that anyway.

I'll respectfully disagree with that.
We all accept that the surface area of a tank is an important consideration, when considering stocking levels, etc..
Whilst the bubbles themselves do not add oxygen to the water, they do increase the surface area between water and gas. As you correctly imply, a rippled water surface has a greater surface area than a totally flat one and so offers a greater surface for the transfer of oxygen to water. Likewise, with aeration, each bubble has its own surface area, thus contributing to increasing the surface area for oxygen diffusion.
A well-oxygenated tank is (usually) good for both fish, plants and friendly bacteria, especially at night, when the plants aren't photosynthesising.

The downside of aeration is that the bubbles create noise and can easily detract from a desired 'natural' look, (although small streams entering larger ones always come with a bubble accompaniment). Also, I've I've already suggested, the ensuing currents formed may not be conducive to those fish that prefer a quieter and more static water pool, although some water movement in a tank is (usually) desirable, to avoid 'dead zones'.

Whilst my tank is currently cycling, I've got aeration on the go and the plants are still doing well.
When my fish are in, I'll probably swap my venturi on my filter outlet for a 'trickle bar', which would mimic an incoming stream more effectively.