I have a lobo colony that has been thriving for months now. but over the last few days I have noticed that the top edges of the lobos are getting white. is this a sign of too much light? or a chemical imbalance? also I have a Mycedium that i have had for 4 months now and has been doing great but over the last few weeks has been turning brown. like solid brown. is this a sign of not enough light? Both are in a similar location in the tank