# Question about filters and CO2 diffusion



## fishbone (Jan 15, 2007)

First question:
Which method of diffusing CO2 works better? An airstone set at the bottom of the tank or hooking up the line directly into the aquarium pump, as close to the impeller as possible? Does it make a difference if the line is hooked in front of the impeller or behind it? (sucking vs blowing water)

Second question:
I've had a Tetra Whisper PF10 HOB filter for my 10 gallon tank forever and have been happy with it's performance. What other similarly designed pumps in roughly the same price range would you suggest for a 20 gallon tank? I'm especially looking for a bit more room in compartments if I choose to insert some additional media. Would I be missing out on anything if I choose to stick with Whisper filters even for my 20g? What are some drawbacks/general complaints?


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## goodie (Sep 2, 2005)

Running it into a pump before the impeller will chop the larger single bubble into many tiny bubbles that will disolve into the water more quickly. You'll still still lose them at the surface, but its the more effective way than using a airstone. The longer you keep them from getting to the surface the better.

I've been using the whisper line of filters for about 8+ years and even though I like them, I possibly would try out the AC (AquaClear)line. I've never used them and have heard good and bad(just like you will with all products). They seem like a very inexpensive filter to buy and to maintain. Since I don't use carbon that would just leave room for more bio /mech media. The only grip that I ever had with whisper, or any HOB filter (marineland) is having to replace the cartrige so often. You can rinse them out in old tank water or even under the faucet, heaven forbid (as long as you have separate bio media or two filters running on the same tank you can do this) but they only last so long. I've used the AC foam for prefilters on the intakes of powerheads and filters and it seems as though they last forever .


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## fishbone (Jan 15, 2007)

So the goal here is to get the bubbles as small as possible.
I might just invest in a diffuser off eBay. Any thoughts about the ones that look like a bell but actually let CO2 diffuse from the top part which is made of a ceramic lid?


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## goodie (Sep 2, 2005)

Yeah, smaller bubbles equal more surface area to come in contarct with the water. 



> bell but actually let CO2 diffuse from the top part which is made of a ceramic lid?


like this?
http://www.aquabuys.com/miva/merchant.mvc?Screen=PROD&Product_Code=j_co2_diffuser
I've never used one, so I couldn't say anything about it.

I made a crude bell diffuser from a soda bottle, but it was *very *slow to disolve the gas. The one above would do much better, I'm sure.

This has a break down of different types of diffusers if you haven't seen it yet.
http://www.qsl.net/w2wdx/aquaria/diyco2.html

If you are a DIY'er the Forced Reactor type are easy to make and do a good job.


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## fishbone (Jan 15, 2007)

The only problem with forced reactor is it's so darn big for a 10g, even the 20 that I am upgrading to soon.


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## goodie (Sep 2, 2005)

Sorry, I was't thinking of your tank size 

I think that this is priced way too high, but it works for small tanks.
http://www.floridadriftwood.com/product.asp?3=404

For your size of tank I would try out the glass/ceramic one that you had asked about. It would probably work fine.


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## fishbone (Jan 15, 2007)

Well, I tried fitting the outlet line to the intake of the filter, but the darn thing rattles when it takes in bubbles. When these come out at a rate of 2 or more per second, it gets loud! Wife complained she slept like crap last night because of it 
How about hooking up a woodstone very close to the intake, would that work well? What about hooking up the woodstone under the outlet, where the water current is strongest? Which would be best?


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