how many bubble bars are too many?

If you're trying to grow plants w/ CO2, even one is too many.

With a tank that size tho, I'd be more likely to recommend Flourish Excel.
 
I agree with Timmain42, bubble bars in my opinion have few appilcations in the aquarium and plants is not one of them as they remove CO2 from the water.
What about using a small power head with a airline attachment fitting so air can be blowen into the tank.

Just a thought
Nick
 
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