C-220 Filter, suddenly with air bubbles
Hello all. I have a Marineland canister filter than I've had at least two years. On occasion, it would spit out some bubbles and do this for a day or so. Last weekend, I serviced the thing as usual and now it spits out bubbles every minute or so. Shows no signs of stopping. I have no external water leaks and, as far as I can tell, have done nothing different this time than I have the times I serviced it in the past.
Any ideas on this?