# CO2 not rising?



## Simpte 27 (Jul 16, 2004)

I recently went out and purchased a cpl of wooden diffusers by coralife. The bubbles are great! Nice really fine mist which rises to the HOB outflow and then get dispersed throught the tank. My ph doesn't fall, and thus my co2 levels are staying the same? I figured that my initial water parameters were way too high (ph almost 9 gh 38 kh approx 18) With r.o. and distilled water I got the PH down to 7.2 gh 7 and kh 7. How can I get more CO2 into the tank? Do I need to add a bell for the diffuser? Any help would be appreaciated.


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## gpodio (Feb 4, 2004)

Your HOB filter is probably outgassing a lot more CO2 than you would like it to. This may be keeping you from reaching higher concentrations. If it's DIY CO2 I'd suggest trying a larger bottle or two bottles going to the airstone, otherwise try a powered reactor if you have the room.

Hope that helps
Giancarlo Podio


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## Simpte 27 (Jul 16, 2004)

OK gotcha. WIll try the powerhead. Thanks for the tip.


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## JanS (Apr 14, 2004)

Simpte 27 said:


> OK gotcha. WIll try the powerhead. Thanks for the tip.


Eek, I just want to clarify that gpodio meant a powered reactor (like a Plantguild reactor with an electric pump on it), not a powerhead. The powerhead would drive the C02 off more.


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## Simpte 27 (Jul 16, 2004)

Right. I got that. Was going to try a DIY reactor with a powerhead and gravel cleaner but as my other post stated I guess I have pearling. I upped the lighting to 65watts over the tank as opposed to 35. Made a huge difference in just 3 hours!

Is there a good "manual" to growing aquatic plants and what type of plants require what? I see some of those tanks posted and they look wonderful! I want one! (Just with fish also.)


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## gpodio (Feb 4, 2004)

Don't take the pearling as a sign that you won't need to change anything. The higher the light, the more important it is to have good CO2 levels. I wouldn't abandon the idea of trying to raise CO2 levels personally, even if you add a second DIY bottle to the tank it will go a long way. Also you could try to reduce the flow of the HOB filter or raise the water level so that it doesn't splash as much.

Hope that helps
Giancarlo Podio


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## Simpte 27 (Jul 16, 2004)

I have raised the water level as far as I can as I had the same thought. I cant change the flow rate of the filter (Penguin 170). I am testing the co2 levels every day and night over the next cpl of days to see if a second bottle is necessary. I used Chucks planted tank calculator and with a PH of 7.2 and KH of 7 I'm only getting 13ppm co2. The calculator says its good and rates 25ppm as HIGH. Now I'm confused again as most websites I visit say 20-30 is ideal. How do I get a lower KH (say 4) and keep my co2 levels high?


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## gpodio (Feb 4, 2004)

13ppm is not bad for a low/medium light tank however I would probably try to bring it to at least 20ppm. Changing your KH will not effect your CO2 level, it will just effect PH. So if you bring your KH down to 4 for example, looking at the following table:

http://www.gpodio.com/co2_chart.asp

You'd probably end up with a PH of around 6.9-7.0 with the current CO2 level. To lower KH correctly, water with a lower KH must be used during water changes. Distilled, filtered, RO.... all will help lower it however I'm not sure that it's really worth the effort. A KH of 7 is not bad at all and lowering it will not help in any way towards CO2 levels.

Hope that helps
Giancarlo Podio


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## Simpte 27 (Jul 16, 2004)

So I should concentrate on my PH levels more than my KH? (Even though its easier to lower my PH by lowering my KH )


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## gpodio (Feb 4, 2004)

You have to be aware of both in order to measure CO2. Knowing your KH and PH will tell you how much CO2 you have. You don't have a "target" PH, just a target CO2 level. For the most of us, we have a fixed or stable KH from our water supply and our PH fluctuates depending on CO2 levels. In your case there is no need to lower KH, so stick with 7 and bring your CO2 levels up to 20ppm if possible, this should result in a PH of around 7.0

Hope that helps
Giancarlo Podio


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## Simpte 27 (Jul 16, 2004)

Gotcha. So I just need to inject more co2 into the water (or get a higher saturation rate from what I already have) Thanks!


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## gpodio (Feb 4, 2004)

That's right, either more CO2 or reduce the amount that is lost by reducing surface agitation from the filter.

Giancarlo Podio


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## Simpte 27 (Jul 16, 2004)

I'm using a diffuser made by coralife. Puts out nice fine bubbles. They are floating throughout the tank. I cant figure out why my co2 levels aren't rising. Are the bubbles supposed to do this. Do I need more current? I am lost on this one. How can I tell my diffusion rate? (if there is a way to determine how much co2 is actually going into the water and not being lost at the surface.


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