Okay so I have a 20 gallon tall planted, with a 65 watt bulb, my plants grow well, and I add liquid nutrients once a week after each water change. I really would like to invest in a co2 device but I'm not sure like which one to get and what not, I'm completely unknown to this equipment. I'm...

i have a diy co2 system on my 55g. it is producing about 5-6 bubbles per second. is this too much and what is normal. also how do i lower it if need be?