Generate Water Movement Without An Air Pump?

Air pumps are used by people for a number of reasons:

1. the beauty of bubbles in the tank
2. to produce water surface agitation
3. to enhance water movement within the tank
4. to power ornaments (opening sea shells etc..)

I have been looking for a way to produce a wall of fine bubbles to generate more water movement within my tank without using an air pump. Finally found the best product on the market. It is made by Eheim and is called a Power Diffusor. They come in different sizes depending on your filter water flow (gallons per hour) and connect to the output of a canister filter in the tank. Works a dream and adjusts well, though the fine adjustment could be better. The bubbles are small and regular (which is hard to get from an airstone). Take a look in this short video I took.

 

Seems kinda noisy.

Might be useful for supplimental aeration when doing heat treatment for ich.

 

Seems kinda noisy.

There is noise caused by the bubbles bursting - true.
I find it less noisy then having an air pump. Most importantly, in the position I have the venturI jet located, it generates water movement in the tank and very little water agitation, which is what I was looking for.

 

Why movement and not agitation? I'm a dumb diver, so my first thought was gas absorption into the water would be greater if the liquid wasn't.. churning, but I'm guessing that isn't right.

 

Why movement and not agitation? I'm a dumb diver, so my first thought was gas absorption into the water would be greater if the liquid wasn't.. churning, but I'm guessing that isn't right.

Just to make sure that we don't have semantics playing games with us I will define what I understand by the terms:
water movement - is the movement of water in the tank
agitation - refers to the "breaking up" of a smooth water surface.

Most tank owners agree that the surface agitation increase gas exchange - from a physics point of view, you get more surface area of water in contact with the air with water agitation then you get from a mirror smooth surface which is the state of minimum surface area in contact with air. Just from a pure practical point of view the shortest distance between two points is a line - every other option (bend, circle, wave etc.) increases the the length and therefore in the tank senario the water surface area in contact with the air.

Like you said - it is not that intuitive, but when you think about it for a while, it is logical

In my case I have a big tank and use the air bubbles to generate water movement within the tank to ensure that the concentration of dissolved substances in the water (CO2, O2, minerals, NO3...etc) is consistent throughout the tank. Works well for me.

 

I just rely on massive water movement via mechanical means; my Fahaka is in a 125 at the moment; it's got two Aquatop CF500s and a 50 gallon sump - actually 50 gallons of water in it (90 gallon aquarium sump build) running at 1k gallons an hour - dc pump.

And I'm pumping ungodly amounts of cO2 into it because of the surface disruption.

What's your specs?

 

I too have a 125g tank. It is a planted tank with two tetra ex1200 canister filters, giving 500g/h flow. I connected a water meter to the both of them and measure the flow over a period of two weeks and then divided.

I don't use any other pumps in the water for water movement. I use a JBL water skimmer which keeps the surface of the water crystal clear with a gentle flow across the water surface without the water breaking. I don't have a problem with gas exchange.

What I have a problem is pumping too much CO2 into the water, which has resulted in me installing a constant test meter that I monitor and I have reduced the CO2 injection to 6hrs a day per day at 60 bubbles per minute.

In addition I have a 11Watt UV system that switches on at night. Two 300W heaters are connected to my tank computer that measures the temperature and controls it within +/- half a degree celcius. The tank is covered and has two variable speed ventilators that are also controlled by the tank computer for a aire movement. The ventilators are set for 50RPM at the nominal tank temperature and the speed increase to 600RPM if the temperature rises more than 2 degrees centigrade (about 10%) above the nominal temperature. If the water temperature increase even more, then the ventilators go to max speed of (I think) 3600 RPM to cool the tank down. This is useful in summer just incase the house ventilation fails and the room temperatures goes up.

The tank computer also monitors pH and alarms are triggered for pH changes and temperature changes.

So that is my set up - yes definitely a tech tank

 

I'd like to know about your computer; I do a little bit with automation (licensed master electrician), so, I'd love to set up some relays and solenoids and automate a few functions.