Do I need an air stone/diffuser?

[Zoomy]

Hi guys.

So I think my fishless nitrogen cycle is almost complete! Which is a relief since this means things didn't totally crash and burn when I moved this past Saturday. This almost means that fish will soon be an actual Thing, and my last (for now) question is:

Do I need an air stone/diffuser?

I mainly ask this because my tank is an 18 gallon TALL, and I plan on getting a betta fish and some corys. Now, when I put everything together, I started out with an air stone in the tank as it was cycling, however it was too big with too big of bubbles for my liking, as it caused a lot of surface movement. When I took it out a few weeks ago, everything seemed fine for the first day, but by day 2 of No More Air Stone, I noticed that the little pond snails in the tank were all at the water's surface sucking air from well... the air. I had NEVER seen them do this before, and while I'm not particularly worried about snails, this makes me worry/wonder about the future well-being of the corys I get.

I guess a secondary question would be, should I need an air stone, does anyone know of a good, little one that makes very FINE BUBBLES, with little surface agitation? As mentioned, I plan on getting a betta as well, and they're not that fond of a lot of water movement.

Thanks!

 

[ole scratch]

Use a wooden air stone. Believe u can get them at petsmart/petco.

 

[Fett999]

It's actually the surface agitation that you need to get oxygen into the water. Bubbles themselves don't add oxygen. I'd look at your filter outlet first. If you can raise that to create more movement on the surface then that should get the gas exchange up and add more oxygen to the water. If you can't then an air stone will aid the gas exchange, but only by creating surface agitation. If you find an air stone that creates almost no surface movement then it won't be adding much in the way of oxygen.

 

[Rivercats]

The reason the snails were floating opened is because most likely they were eating on the biofilm that usually forms in a protein layer when surface agitation is too low. When oxygen is too low in the water you would see fish at the surface trying to gulp air and snails will actually crawl out of the tank, especially certain types of snails like nerites.

 

[molliwopp]

It's actually the surface agitation that you need to get oxygen into the water. Bubbles themselves don't add oxygen. I'd look at your filter outlet first. If you can raise that to create more movement on the surface then that should get the gas exchange up and add more oxygen to the water. If you can't then an air stone will aid the gas exchange, but only by creating surface agitation. If you find an air stone that creates almost no surface movement then it won't be adding much in the way of oxygen.

More air exchange is done at the surface but bubbles in the water will add oxygen also.

 

[Fishfur]

I don't think air bubbles really add any significant amount of oxygen to water in a tank, because a certain amount of time is needed for the actual gas exchange to occur. It's not quite an instantaneous event, and the bubbles rise so fast once they exit a stone, there is very little time for much oxygen to change places with CO2 in the water column.

Their primary benefit is that when they reach the surface, the bubbles increase the surface area, which increases the area available for gas exchange to occur. You can do pretty much the same thing by having the filter output 'fall' into the water, with some splashing, instead of simply going in below the surface quietly.

You might also have a very small submersible pump at the bottom, one that allows the flow to be adjusted. This would circulate water and prevent potential dead spots, which may happen in 'tall' tank configurations, but that flow would hopefully not bother a Betta too much if you kept it at low output.

Bear in mind, Betta fish do not care for a lot of water movement, in terms of current, no matter what is causing the current. So any circulation has to be adjusted to keep a Betta from being blown around. Those long fins are almost like sails in the wind in too much water current.

You can get also get air stones that are finer grained than the average ones, though you may have to order them. You can control the bubble stream better by putting an adjustable air valve on the tubing from the air pump.

There are also plastic stones, which are nice because they are self weighted, and stay down on their own, and are easily cleaned. They come apart for cleaning and last darn near forever, whereas the ceramic composite ones do not last all that long. I had a composite one fall to bits in less than six months used inside a sponge filter. Wondered why the bubbles were so big, took the filter apart and found the stone was nearly gone. Plastic ones don't break down like that, or rot like wood eventually can. But they tend to be brightly coloured, which I'm sure some would find annoying if they could not be hidden.