Join Date: Sep 2005
Location: Jakarta - Indonesia
If you are sure what you are doing, just cut of excess pipe and reconnect the elbow. I think your lfs or perhaps "home depo" should carry some replacement tubing should you need it. A saw would certainly help.
In my opinion, some surface "agitation" in the context of some water movement, but not the type where you have springkling water is necessary to have in a very very small amount. Try to set it that you still can see a water movement on the surface, but no real agitation. This way you can avoid a film coating of protein from building up on the water surface (which can block light by a small amount and prevents water from "breating").
The matter of balancing O2 inside your tank while maintaining CO2 is a relative for each tank, depending on the population, photo period, plant load and your rate of CO2 injection. If you see your fish gasping in the morning and checking your CO2 level to be 30-40 ppm, then you will need an aerator on a timer to work on the off photoperiod time (when the lights are out). This is better in terms of practicality and pH swings. Just leave the CO2 running day and night. When you have the lights on, usually there will be no need at all for additional means of adding O2 into the tank. All will be supplied by your photosynthesizyng plants.