hi there, im a newbi and havent had the calcium probs yet but just a thought on the hood could you not use something like lemon juice but making sure you clean it off really well when your done as for the cut outs i would try and "scrape" as much off as possible. i will keep an eye open for you and see what i can dig up. where abouts are you?
Juwel Vision 180 Tank with 1 (pink) community bulb and 1 blue moon bulb, black background and black gravel:
1 Bristlenose Pleco, 2 Bala Sharks, 3 black tetras, 3 mickey mouse platys, 3 normal platys, 7 hariquines, 3 male guppies, 6 female guppies and 4 female bettas.