# newbie question about CO2 saturation



## fishfry (Apr 15, 2004)

I am new to using pressurized CO2, and I have been reading 25 ppm is about the highest you want to go. I am curious as to how much of an effect on the plants a difference between say 15ppm and 25ppm there is. Does that little of a change do THAT much?

THanks!


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## Bert H (Mar 2, 2004)

I keep mine around 30ppm. No problems with the fish, plants are happy and algae is at a minimum. I have read many threads in various boards which state there's a relationship between bba (black brush algae) and lower co2's. 

How much lighting are you using? If you have high lighting, I would definitely go higher than 15ppm.


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## fishfry (Apr 15, 2004)

I am using 64watts of PC on a 20 gallon tank. Right now I am using a carbo-plus that keeps CO2 at about 12ppm and am waiting for my JBJ regulator to come so I can switch to pressurized gas. I did have a bad outbreak of BBA that has since ended with an increase in ferts. and the addition of SAE and Amano shrimp. My water is kept very acidic so the carbo-plus doesn't work too well.


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## Error (Apr 16, 2004)

I know one of the current recommendation that has been floating around is 20-30ppm CO2. Mine has always been lower (DIY), and I have had problems with green spot algae lately. Can't say I've ever had BBA.


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## gpodio (Feb 4, 2004)

CO2 unlike some of the other elements is absorbed differently based on it's concentration. Some nutrients are sufficient as long as they are available in quantities higher than 0ppm, but CO2 has to be "force fed" in order to push the plants to a faster growth rate. 15ppm will work, 30ppm will simply speed things up even more. I found I had BBA problems with unstable CO2 levels when using DIY CO2, yet with pressurized CO2 I haven't had problems if I kept a steady 15ppm. I do however try to keep it around 20-30ppm. If you have a lot of light, then 15ppm may be on the low end and you would probably notice some benefits by raising it some. In a low/medium light tank, 15ppm is a nice number in my opinion.

Error, I had good success at reducing green spot by reducing traces (including FE). Might be worth a try.

Hope that helps
Giancarlo Podio


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## Corigan (Mar 15, 2004)

gpodio said:


> I found I had BBA problems with unstable CO2 levels when using DIY CO2, yet with pressurized CO2 I haven't had problems if I kept a steady 15ppm.


I have had the same experience on my 55g recently. Got rid of the DIY co2 (and subpar co2 levels) and installed a pressurized system. The BBA is now gone and I run my presurized at about 23 ppm.

Matt


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## skids (Mar 23, 2004)

The difference between 15 and 25 ppm CO2 is almost double, and so if every needed nutrient (N,P,K, + traces) is available with abundant light (2-4 wpg), you can double the growth rate of plants (approximately). But at the same time, you can double the growth rate of algae if it has the upper hand, or other nutrients are lacking or in excess.

Until you get a handle on your fertililizer dosing, it's better to stay around 15 for a few weeks. Otherwise you may be juggling too many variables at once.

Extremely fast plant growth can have other issues you may not like that much, like needing to trim overgrowth every week. Or someplants grow so fast they over shadow and inhibit slow growers like crypts.

At levels in excess of 30ppm there is actually some research indicating inhibition of nitrate and ammoinia uptake, so too much of a good thing... would make potent ferts available for algae.

The goal (which I am still working to acheive) is to promote healthy plant grow so they grab the available ammonia, phosphate and nitrates before the algae does.

Good target levels are (according to Tom Barr and others) :
kH 4-5 deg, 
CO2 15-30ppm < work on this first
nitrate 5-10 ppm
potassium 20-30ppm
phosphate 0.4 - 1
Iron 0.5 - 2 (tough to measure accurately)

good help:
http://www.aquatic-plants.org/est_index1.html

he recommends people start simpler with lower light say 1-1.5 wpg, and natural CO2 or lower levels to enjoy low maintenance tanks. I of course being a beginner also (to plants), completely ignored this advice and have a grab bag of issues I've just gotten bak on top of but am now finding the chores of pruning and replantng to be taking about 1 hour/week. So I've just started a low maint tank 25gal with some older established plants (java fern, anubias, and valisneria).

CO2 and light are sort of your gas pedals, push them hard and plant growth acelerates, but like a car, if you are missing or have too much other fuels, the mixture gets too lean or rich and the car sputters. At high speeds it gets out of control much quicker. Also if you overdrive CO2 but are missing in needed macro or micronutrients you will get wierd leaf deformities; curling, yellowing, pinholes, long stems but short leaves, etc. Also other plants may not develop their reds and purples.

JM2cW


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## fishfry (Apr 15, 2004)

I increased my co2 and it is 29ppm, so far I am very pleased with the increased growth rates. After I increased the co2 they started to pearl like never before. My ferts are all within the recommended ranges, I did a lot of research on that, so I am happy.


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