I want to add a simple c02 injection to my planted tank. I do not want to pay the $100+ bucks for a large solenoid so i found a simple regulator by Sevenport. There is a super simple one and then one with a "decompressor". It notes that the only difference is that the more expensive model has a decompressor and the cheaper one is straight pressure. Whats the difference in regards to an aquarium?