I also use a small internal filter for CO2 dispersion and it works great. I bought the cheapest, smallest I could find and removed the filtration bar the open weave sponge, cut ope the intake area at the base and let the CO2 hose sit up inside. I've recently read of people using bamboo chopsticks. Some were cut flush with the tube and others on a long angle similar to a fruit tree graft. These are cheap, readily available and easily replaced.
As I discovered, a silicone seal is compulsory irrespective of how well all the components fit at the bottle end. The gas is being forced through tiny holes and looks for path of least resistance. That's why I went for the through the filter option.
Great moss ball too!
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