Diffuser placement

[Scott F]

So I've finally got all the parts to do CO2 in my 55 gallon. Have a fluval filter, but am not going to do inline.

I'm wondering where the best placement for the diffuser would be?

My initial thought is below the outlet tube, OR to get a circ pump and put it below that.

Your thoughts ??

 

[meegosh]

I think you're on the right track. What are you using to diffuse? You need to get the CO2 circulated throughout the whole tank so a high flow area is always good.

 

[Scott F]

I've got a 60mm diffuser from Green Leaf. I also picked up a Hydor Circ pump that I could use in one of my other tanks, but thought that if I place the diffuser low, with the circ pump over it, that I'd get a decent displacement as opposed to using the output end of the filter which sits just a couple inches under the water level.

 

[Aquatic_Adam]

The best place to put it...is not even use a diffuser!

Your Fluval canister filter will work the best

Feed your tubing from the CO2 directly into the uptake for the filter. This maximizes time to absorb, circulation, and the impeller of the canister will break it down into smaller bubbles with more surface area for the water to take it in.

 

[meegosh]

Predfan is right, you could run it through the intake of your canister. I did this with a power head but quickly gave up using that method after hearing 2-3bps hitting the impeller. It is quite noisy chopping CO2 bubbles. Also, some say that the bubbles them self can cause vibration issues in the impeller housing. This is caused by the blades vibrating/stressing when the bubbles hit them. You also pose a risk of getting CO2 trapped in the canister. You could always "burp" it if that happened though.

 

[Scott F]

I guess it won't hurt to try that method first. Thank you !

 

[phin]

for a week, after I had set up my CO2, but before I had built my diffuser, I ran my CO2 directly into my canister intake. The CO2 would puddle up and get trapped in the top of my canister, then when the airpocket inside my canister got big enough, some would get chopped up by the impeller, spewing a cloud of tiny bubbles into my tank. The noise wasn't an issue, it sounded like static or white noise for a second every few minutes or so.

I had concerns with this though. First, to me, it seemed as if there was always a CO2 bubble in my canister, and with much probablility that CO2 bubble was in constant contact with a part of the gasket surrounding the motorhead. This can't be a good thing for the gasket over an extended period of time. If the CO2 bubble wasn't in constant contact with the gasket, it was, in the very least, in constant contact with the plastic housing of the motorhead. I imagine, over time, this is not good for the filter, as CO2 will degrade the plastic the canister is made of.

Also, I don't think I got as much diffusion as I figured I would get. The bubbles that would burp out of the canister every few minutes weren't all micro bubbles like you would see with a skimmer, they varied in size, from micro to pea size. Also, since my outflow from the canister is near the surface the larger bubbles quickly broke on the surface, causing me to lose that CO2.

I built an inline reactor. It was very easy, very cheap, and now I get 100% (or very close to it) diffusion.

 

[meegosh]

What kind of Fluval filter do you have? Is it HOB or a canister? If it is a canister I would build a DIY inline reactor. You can make these for less than $10 in parts at a HW store.

If I were to do a planted tank again I would definitely go with an inline reactor. When I had my high tech tank up I used a powered reactor. It is another thing in your tank but was able to hide it with a bunch of stems in the corner. It was very efficient and didn't have many large bubbles escape.

 

[foster53]

I diffuse co2 into my tanks through a powerhead also. I run it into the venturi inlet and the impeller really chops up the bubbles. It is a little noisy, but not bad.