IMO, If you don't use it alot, use of co2 is cost prohibitive, and very dangerous if you don't buy a regulator (cost prohibitive part). Those things can have in excess of 1000 pounds of pressure on the valve. To give you an example, 10 pounds pressure can hurt if something blew apart and hit say your hand. There are guys that say "I open the valve only a little and that keeps the press low". They are right, Until what your blowing hits the obstruction then the pressure in the pipe tries to equalize with the bottle Thats when the drainjet comes back at you. Please don't buy a co2 bottle. AquaTechPool is right, call a pool guy.
K~I won't pursue that route...I'll call a pool guy.
Thanks