I clean it out twice a week but after a couple of days there's a fishy smell. I'm concerned one of the piggies has UTI but when I googled it, this wasn't a symptom. They eat well, one drinks loads and the other doesn't seem to drink at all but is healthy.
Any experienced guinea pig owners able to advise me on the smell. (They live indoors in a large hutch in winter, and outside in a different large hutch and a grass run in summer. We've had them since July and they're about 10 months old. I feed them lots of hay, piggy muesli (they won't touch pellets) and a mix of fresh stuff every day.