Good powerhead for DIY CO2 reactor?

**JoeE** · 04-23-2012, 05:39 PM

I'm working on a DIY CO2 reactor using an airstone to release the bubbles into a bottle, with a powerhead also attached to the bottle to diffuse the CO2. I purchased this submersible sponge filter to function as a powerhead but it isn't providing nearly enough circulation to break up the bubbles and after a few hours I'm left with an air pocket at the top of the bottle. What powerhead should I look for - how many gallons per hour of filtration should be my target to ensure adequate diffusion?

**pjaldave** · 04-23-2012, 05:50 PM

Wait. This is hard for me to understand. Diffuse... means, to remove excess CO2 in the tank or you want the CO2 to be distributed evenly in the tank?

Also, a sponge can never be a powerhead.

**JoeE** · 04-23-2012, 06:13 PM

Diffuse means to spread evenly throughout the tank. Essentially I'm trying to build a mixer - the airstone releases tiny CO2 bubbles into the bottle, which then float to the top and get mixed up with water circulating in from the powerhead, also attached to the bottle. The CO2-rich water than flows out the open-ended bottom of the bottle.

The small sponge filter I had may not be a powerhead in name, but it worked like one. It sucks in water from the bottom and then the tube on the side spits it out. It just isn't providing enough circulation to mix the CO2, probably less than 20 gallons an hour.

**pjaldave** · 04-23-2012, 06:24 PM

Do you not have enough filtration to circulate the water in your tank?

And sorry, didn't look at the link you gave provided you said sponge filter. Which is btw, just an internal filter.

**JoeE** · 04-23-2012, 06:54 PM

As I understand it a homemade CO2 system requires quite a bit more circulation than normal filters provide to break up the tiny CO2 bubbles to where they don't just float to the top.

**pjaldave** · 04-24-2012, 07:11 AM

Not really sure, but usually whatever CO2 it is, you don't need another powerhead for it if you have enough water movement.

You only turn on another airstone (connected to a pump) or a powerhead to disrupt the surface at night. So that when your plants does not need CO2, surface agitation will help lessen the amount of CO2 and bring O2 to the water.

Does that make sense?

**Cermet** · 04-24-2012, 11:58 AM

I like what pjaldave suggested.

**dmagerl** · 04-24-2012, 12:00 PM

The picture on the box of that filter shows a short length of tubing so it can suck in air for aeration. Have you tried running that tube to the top of your bottle so it sucks in the air bubble and breaks it up into the exhaust of the filter?

If all you're doing is circulating water in a bottle, the tiniest powerhead you can find should be all you need.

**JoeE** · 04-24-2012, 12:21 PM

Originally Posted by dmagerl

The picture on the box of that filter shows a short length of tubing so it can suck in air for aeration. Have you tried running that tube to the top of your bottle so it sucks in the air bubble and breaks it up into the exhaust of the filter?

If all you're doing is circulating water in a bottle, the tiniest powerhead you can find should be all you need.

That makes a lot of sense. I will try that, thank you.