Not so sure about an acan.mine love moderate flow and I had it in the shade and it barely opened.I moved it into the light and it opened right back up.+1 on mushrooms those things grow anywhere
I haven't seen flow affect acans at all--low or moderate. Light, they definitely do not like bright light--at least mine don't. If my Goby finds a way to move the sand so an acan falls into direct light, the acan retracts.