I have tried many of the options described on different forums to get the CO2 dissolved. Power heads, diffusers, bubble ladders ect.ect. Now what I have done is connect the CO2 line to the output hose of my EHEIM 2234 cannister using a check valve rite near the outlet of the pump. This then travels thru my chiller and out into the tank. I see no CO2 bubbles coming out into the tank, so I guess its getting dissolved 100%. I get pearling after 1hr lights on, and according to the Drop Checker(don't trust it too much) I have plenty of CO2 in the water. This way is clean and hassel free for me and seems to work great, no clogging of diffusers, no cleaning of crap sucked into the powerheads ect. ect. I have a chiller due to the fact my tank, without it reaches 33C. This is Thailand. Just another option for some who may run chillers.
Cheers,
Singtoh