HCA: Hermit Crab Association

I cannot post pics here sadly, but in one corner of my tank i noticed green moldlike (strips?). There is some brownish things too, and its just under the sand on the glass, i removed it, but what is it, is it a danger to my crabbies?

It's algae. I had it in both of my tanks because they are near windows in my pet room. It's not harmful, I left mine in there for a while. I only recently fluffed up all my substrate in both tanks and got rid of it. I use a big plastic bubble envelope taped on the left side of my big tank to keep the sun off the glass. I'm going to do the same with the front of my smaller tank this weekend.

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