Internal Filter Question...

[Karplunk]

Does internal filter aerate the water? or do I still need an air stone?

 

[waterdrop]

Airstones are almost entirely decorative and maybe a little bit functional. You don't need one.

The most significant factor in getting a good exchange of gases between the water and the air is the movement of water at the surface. Thus, anything that moves the water around across the surface will be in fact be vastly superior to a bubbling airstone. I, like many others, used to think that of course all those little bubbles would greatly increase the surface area, but it turns out that a bubble is not there long enough to significantly increase the effective surface area. Directing the output of your internal filter such that it moves water at the surface will make a bigger difference. This is also the reason that big external filter systems often come with "spraybars," horizontal tubes with holes placed at the water surface to move a large surface volume sideways.

Now one good thing that airstones do is to aid in moving water from lower levels to upper levels of the tank, thus helping with the tanks circulation pattern. Again, this is only a mild method of doing this and often aquarists will choose to use a water pump called a powerhead to promote much stronger circulation in the tank. There's no doubt though that if its the look you want, a stream of rising bubbles from an airstone can be quite an attractive addition to an aquascape and there's nothing wrong with that, its just that it should be understood that its mostly decorative and not a necessity.

~~waterdrop~~

 

[bitteraspects]

just position your internal so that it creates a ripple at the waters surface. this will provide all the aeration you need.