my tank has been up and running for 7 years and i have a problem that i need advice on, my overflow is full of hardtube worms. i don't mind them in the tank but they have restricted the flow of the overflow, anything i can soak it in like say "limeaway" or something that would dissolve the tube without hurting the overflow? :unsure: any suggestions would be great, if i only knew more when i started the tank would have been drilled and no overflow used. :doh: