To be honest I can't remember when I set this one up. It must be over over at least 6 months now, probably more. Always been stable, never had any problems til now. Everything seems to be fine, the fish seems happy, but the corals aren't fully opening. It's a little bit better this morning. I was looking at the skimmer closer and noticed it isn't making a tower...it's still bubbling inside the skimmer but not rising. Maybe the air inlet is blocked with salt creep or something? I'll get it out and give it a good clean today.

Cheers