I've been doing it that way for 2 years on 3 different tanks, first with diy, now with pressurized. It works great, as far as I'm concerned. I would warn you that when you start to hear the gas bubbles 'burping' you need to clean out the filter floss.
Yes that works. It's not the most efficient however.
When I started, I did this just to start getting CO2 into the aquarium. I then looked at the DIY things to increase CO2 diffusion efficiency. Now a days I think you can purchase an eheim diffuser relatively cheap.