CO2 through powerhead

[scottward]

Hi Tom.

Following your advice, I no longer have the CO2 going into my canister filter, but now have it feed into the inlet of a 2000lph powerhead. The powerhead is 'misting' the CO2 out into the water along the length of the tank.

My question is - does the mist need to be a constant stream (which would only be acheivable by turning the bubble rate up really fast)?

At the moment the CO2 comes out in 'puffs' about 1-2 seconds apart.

Circulation is good though, at least I think so anyway.

Scott.

 

[tedr108]

Puffs are fine. I had puffs coming out of a powerhead in my EI tank and everything worked quite well.

The sound of the puffs annoyed me occasionally, since the tank was in my bedroom, but I got used to it.

 

[scottward]

Puffs are fine. I had puffs coming out of a powerhead in my EI tank and everything worked quite well.

The sound of the puffs annoyed me occasionally, since the tank was in my bedroom, but I got used to it.

Cool. Thanks for the reply. What size was your tank? I wonder if tank size would have anything to do with it - mine is 100g.

Hmm. I guess the puffs would mean that the CO2 levels coming out of the powerhead are variable, but maybe with the current pushing it along it evens out?

 

[mi5haha]

the sound would be much smaller if using a needle wheel pump since it has more blades inside than 6 blades only for conventional powerhead.

you can also use a syringe needle (stainless steel) adapted to the Co2 pipe, and let the powerhead "suck" the smaller bubbles from the syringe needle if you could mount the Co2 pipe on the water inlet of the pump.

Most needle wheel pumps have their own "air sucking" mount, so that would make the mounting Co2 pipe on them easier. The problem is that the "sucking" force is so great that if you set your bubble counter at 2/s, the powerhead may increase it to 10 bubbles/second. So a syringle needle can help to check this sucking speed.

 

[tedr108]

Scott,

My tank was 50G and I only had a 180gph (about 700lph) pump for my CO2. I was doing about 3 bps in my CO2 bubble counter. I had good flow in my tank and the CO2 powerhead's flow actually mixed in very well with the flow from my canister filter. You'll need about 6 bps (or a little more) to keep your CO2 at 30 ppm or so -- assuming you don't have a water fall or the like removing your CO2. It's hard to count that fast (6 bps), so you'll probably have to guess.

 

[scottward]

the sound would be much smaller if using a needle wheel pump since it has more blades inside than 6 blades only for conventional powerhead.

you can also use a syringe needle (stainless steel) adapted to the Co2 pipe, and let the powerhead "suck" the smaller bubbles from the syringe needle if you could mount the Co2 pipe on the water inlet of the pump.

Most needle wheel pumps have their own "air sucking" mount, so that would make the mounting Co2 pipe on them easier. The problem is that the "sucking" force is so great that if you set your bubble counter at 2/s, the powerhead may increase it to 10 bubbles/second. So a syringle needle can help to check this sucking speed.

Thanks mi5haha for the info. I have heard of needle wheel pumps but wasn't really sure what they were. Do you know if this is just to make things quieter or does it improve the efficiency? I'm guessing it is only the former? I will do some research...

 

[scottward]

Scott,

My tank was 50G and I only had a 180gph (about 700lph) pump for my CO2. I was doing about 3 bps in my CO2 bubble counter. I had good flow in my tank and the CO2 powerhead's flow actually mixed in very well with the flow from my canister filter. You'll need about 6 bps (or a little more) to keep your CO2 at 30 ppm or so -- assuming you don't have a water fall or the like removing your CO2. It's hard to count that fast (6 bps), so you'll probably have to guess.

Thanks for the info there mate, appreciate it. Yeah - I often wondered how people actually measure something like '6bps'. When it gets to this level, I don't see the point of bothering to use a 'bps' type scale anymore! ;-)

I guess the best move, as Tom often points out, is to let the plants be my guide. At the moment things are ok, but nothing is really growing much atm. I think my plants need some time to recover from poor CO2 in the past.

 

[mi5haha]

Thanks mi5haha for the info. I have heard of needle wheel pumps but wasn't really sure what they were. Do you know if this is just to make things quieter or does it improve the efficiency? I'm guessing it is only the former? I will do some research...

needle wheel powerhead has its 14 blades in stick form (another version is brush like), so when they chop Co2, the sound is much smaller than flat blade of normal powerhead with 6 blades.

I may say that needle wheel powerheads chop Co2 better than DIY type of needle wheel powerhead, and quieter in both ways.

You need to locate smaller ones (around 10W) to put it into the tank. If you get one with 20W (brush type), it would be too powerful to use in tank, and you have to put it outside the tank in connection with canisters (in condition it is water/dry type).

 

[shoggoth43]

Thanks mi5haha for the info. I have heard of needle wheel pumps but wasn't really sure what they were. Do you know if this is just to make things quieter or does it improve the efficiency? I'm guessing it is only the former? I will do some research...

For CO2 injection it's more efficient. If you splash around some soapy water with a flat paddle you'll get some bubbles. Now if you splash around that same water with a strainer you get lots more and smaller bubbles. It's the smaller bubbles we're after. Smaller bubbles means they hang around longer in the tank and/or dissolve faster. The fact that it usually ends up quieter is just an added bonus.

-
S

 

[wilsar]

For CO2 injection it's more efficient. If you splash around some soapy water with a flat paddle you'll get some bubbles. Now if you splash around that same water with a strainer you get lots more and smaller bubbles. It's the smaller bubbles we're after. Smaller bubbles means they hang around longer in the tank and/or dissolve faster. The fact that it usually ends up quieter is just an added bonus.

-
S

many smaller bubbles of the same volume gas has a greater surface area for solution.

 

[scottward]

many smaller bubbles of the same volume gas has a greater surface area for solution.

But I guess less circulation is the trade off?

 

[scottward]

While I think of it...can the CO2 bubbles actually completely dissolve? I'm sure I read somewhere that the CO2 within the bubble enters the water, but it swaps places with other gases that are in the water, so the bubble sticks around.

Is this fact or fiction? Is it possible to completely dissolve a CO2 bubble?

My understanding is that CO2 disolves easily into water - if this is the case why do I actually see these tiny little bubbles whizzing around in my tank for so long?

Almost sounds like the above may be fact?

Scott.