I agree that it needs more. I make something like you have made. Put 2 liter drink bottles on each end of the 1/2 inch pvc. Also put a hole in the bottom end of the bottle and put several on each "limb". Sand everything with 40 or 60 grit sandpaper. If your main pipe is 4" you can put a 32 oz. Gatorade bottle in the top of the pipe. I also use a 12" concrete block at the bottom to help it stay upright.