Leathers being a softie, calc isn't a huge factor. I have a tyree green toadstool and a large regular toadstool. Sometimes they close up for a day or two at a time, sometimes they open all day and night. It will even stay open sometimes with a crab crawling around on top of the toadstool. They don't require a ton of light, and i found mine likes lower flow. They are filter feeders, so you can't really feed them either. Nitrates do make it unhappy, but i had mine open all the time in a tank that had nitrates off the chart (api test kits) for almost a full year. They just kind of have a mind of there own i guess you could say. Tempermental is a better word maybe.