# Do you really need co2?



## piranha333 (Aug 23, 2008)

I have an 90w sorta purple light bulb i got from a lfs store and a 30w with another sorta purple bulb i got from the lfs. I have 2 little fern plants, a moss ball, sword type of plant and bushy floating ones i got out of a pond. My question will these plants be able to live ok without co2 or will they eventually need it? Sorry for not knowing what types of plants. Oh and its a 75 gallon tank.


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## ryanimpreza (Jul 19, 2006)

piranha333 said:


> I have an 90w sorta purple light bulb i got from a lfs store and a 30w with another sorta purple bulb i got from the lfs. I have 2 little fern plants, a moss ball, sword type of plant and bushy floating ones i got out of a pond. My question will these plants be able to live ok without co2 or will they eventually need it? Sorry for not knowing what types of plants. Oh and its a 75 gallon tank.


what is the kelvin rating on the bulbs....5500k,6700k,12000k etc. etc. and no you dont need to run co2 unless you are pumping a lot of light into the tank. Although your plants will do better with co2 regardless of the lighting. So always good to have it but not always needed.


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## Trigga (Jul 1, 2006)

i believe once you get above 2wpg you should be using co2


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## piranha333 (Aug 23, 2008)

O i guess i should be good. I just was wondering if adding more plants can hert it in any way?


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## cobrafox46 (Jun 2, 2008)

Are there fish in the tank? I always wondered if plants will grow without CO2 injection or fish in the tank. Anyone know?


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## maknwar (Jul 16, 2007)

My 125 has 1 wpg and no co2. I do occasionally use flourish excel. Plants will grow with out fish as long as they have what is needed (light, nitrates, carbon source). Fish give you the nitrates, and carbon source needs to come from somewhere. With out one of them, the plants will not grow. Speed also is based on the amount of each. With more light, you need more of the others. So with more light, you are going to need to add co2 and add nitrates.


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## cobrafox46 (Jun 2, 2008)

So what carbon source would you use with no fish.


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## maknwar (Jul 16, 2007)

cobrafox46 said:


> So what carbon source would you use with no fish.


co2 or flourish excel


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## DiPpY eGgS (Mar 6, 2005)

piranha333 said:


> Are there fish in the tank? I always wondered if plants will grow without CO2 injection or fish in the tank. Anyone know?


As long as you dont have more than 1.5wpg, no CO2 is really needed -although it never hurts. In fact, it helps out a lower light tank very much 
Keep nitrate levels 10-25ppm, phosphate levels @ .5-2ppm, (optimum) and there is no need for fish.


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## Dr. Giggles (Oct 18, 2003)

DiPpY eGgS said:


> Are there fish in the tank? I always wondered if plants will grow without CO2 injection or fish in the tank. Anyone know?


*As long as you dont have more than 2wpg, no CO2 is really needed* -although it never hurts. In fact, it helps out a lower light tank very much 
Keep nitrate levels 10-25ppm, phosphate levels @ .5-2ppm, (optimum) and there is no need for fish.
[/quote]

Good to know. I feel like a dumbass around plants but getting more knowledgeable by the day. I think a planted 75G is soon to be ventured into.


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## MiGsTeR (Jan 19, 2008)

Dr. Giggles said:


> Are there fish in the tank? I always wondered if plants will grow without CO2 injection or fish in the tank. Anyone know?


*As long as you dont have more than 2wpg, no CO2 is really needed* -although it never hurts. In fact, it helps out a lower light tank very much 
Keep nitrate levels 10-25ppm, phosphate levels @ .5-2ppm, (optimum) and there is no need for fish.
[/quote]

Good to know. I feel like a dumbass around plants but getting more knowledgeable by the day. I think a planted 75G is soon to be ventured into.
[/quote]

Yea now am a little confused. Why would you need Co2 when you have a more than 2 wpg of light but not necessary when you have 1.5 wpg? If you have little light, shouldn't it be the limiting factor of plants growing, thus needing Co2 to balance it out? No the other way around.. Someone educate me


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## Piranha Guru (Nov 24, 2005)

MiGsTeR said:


> Yea now am a little confused. Why would you need Co2 when you have a more than 2 wpg of light but not necessary when you have 1.5 wpg? If you have little light, shouldn't it be the limiting factor of plants growing, thus needing Co2 to balance it out? No the other way around.. Someone educate me


The higher the light, the higher the growth rate of plants = the greater need for more carbon (CO2). It helps the plants out-compete the algae. CO2 at lower light doesn't hurt, but you can get away without it as light is the primary limiting factor. Balancing your ferts is more important as well the higher the light levels as things can go wrong so much quicker. Watts per gallon is subjective too as regular fluorescent bulbs T-12 or even T-8 don't put out as many lumens as compact fluorescents or T-5s...tank size and depth is a factor too.

At home, I like to add CO2 to moderately-heavily planted tanks over 1.5 wpg T-5 or 1.75g compact fluorescent...partly because I have too many tanks. I use Fluorish Excel for anything lower than 1.5 wpg. My water at school sucks, so it's Fluorish Excel all the way and the tanks are low-moderately planted.


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## maknwar (Jul 16, 2007)

The WPG is not exact. Depending on your setup, you might need co2 at 1.5 wpg. If you have low light, you dont need co2 because the light is the limiting factor. The plants are using the co2 already in the tank with low light. Add more light, and the plants will use up all the co2 so you have to add more.


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## MiGsTeR (Jan 19, 2008)

I forgot to consider them growing faster with more light.. haha Thx for the info guys


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