CO2 Newbie - 150 Gallon

For your 150g, I think that a 20 lbs CO2 cylinder would work very well.

Are you handy with tools? Usually we can build CO2 regulators at reasonable prices using high quality parts.

oldpunk78's Sticky has a ton of good info. The very first post has some links for DIY and general information: http://www.plantedtank.net/forums/showthread.php?t=148509

I go through

AquariumPlants.com

For all of my Co2 needs, they carry everything you'll need to get you going. Plus they have amazing customer service that can assist you with any questions you may have.

Me personally I'm resealing my 100 gallon tank next month, and going high tech planted with it. I plan to go with a 20lb Co2 cylinder, a Milwaukee Regulator w/ solenoid, and a DIY Co2 inline Reactor with Magnum 350 canister filter. My DIY inline reactor resembles the AquaMedia 1000 reactor for 100% disolvability of the Co2.