Thanks! I'll do a water test when I get home. there shouldn't be any ammonia because It's an established tank but I'll check to be safe. I haven't added plant fertilizer recently.Don’t worry about the string of poop. That’s very common but we try not to have it in our lovely pictures.
Why is there bubbles on the surface that have not popped? Is there any ammonia? Or did you add plant fertiliser recently?
Do you have the results of a water test?