CO2 setup question.... help +rep

Whats up guys. "a friend of mine" has a closet grow and is having issues with heat which is being takin care of, however he wants to intoduce CO2 into the room to help out and to help plant growth. its only 3'x3' or about 1 square meter. he has two-20 oz. (40oz. altogether) tanks that were used for paintball.. he was wondering if he could use both together somehow in the small room. would this be efficient and/or enough???? how could he combine them to make one 40 oz tank... so to speak???? Ant hep would be great... +REP for intelligent answers. THANKS

Do you realize there is a stickied guide to CO2 at the top of the forum?

Grow room area: 27 cubic feet
Amount of CO2 required: 0.0324 cubic feet
On time: 1.944 minutes

At this flow rate:
If you are using a 20 pound CO2 bottle with a regulator, it will last 174.8 hours.
If you have a CO2 Generator a 5 gallon propane tank will last 540 hours.

This form will calculate how much CO2 will be needed to fill a grow room to the required level. It will also determine how long it will take to fill at the given rate.
It will not calculate how often you will need to refill the room with CO2. There is no way to calculate how much the plants will use or how much leaks out! Usually you would want to refill just after an exhaust cycle or every 3 hours.
*The air already has about 300 PPM so you only need to add 1200 PPM more to get the optimum level of 1500 PPM.
Enter the grow room length in feet Feet Enter the grow room width in feet Feet Enter the grow room height in feet Feet CO2 to add in PPM
(Parts Per Million) PPM* Flow meter setting or
generator size in CFH
(Cubic Feet per Hour) CFH
CO2 is an odorless, invisible, and non-flammable gas. It is also safe for humans in the maximum concentrations recommended for plant growth. The average level of CO2 in the atmosphere is about 300 PPM (parts per million). If the level decreases down below 200 PPM in an enclosed growing area, plant growth slows to a halt. Through the years of testing and research, the optimum enrichment level of CO2 for plant growth has been agreed to be about 1500 PPM. With CO2 enrichment, under good conditions, plant growth rates and flowering will increase 20-100%. CO2 can be used from seedling right through harvest.

yeah i saw it but i was just seeing what people thought about my tank size.. 2-20 OZ. tanks. im thinking there to small. id have to refill way too often i think but still not sure. i guess it depends on how long it would run each day. i figure it would be about an eighth the size of a 20LB tank