Reef Builders - The Source for Reef Keeping Information

I found these guys attached to the glass.. and congregating at the edge of the sand/gravel where it meets with the glass... i saw on here that the white flatworms are safe and OK.. but is it the same for these guys or do I need to do something about them? thanks for the help.. 1 year old tank..but newbie for me.. bought it from a friend that is moving to CA... I AM ADDICTED!

this one is about 5 mm long.. the others are smaller..

thanks for all the info.. and the help, too!

Small numbers are OK, but rarely do they stay in small numbers. From what I remember in my reading they are photosynthetic, which means just the act of having our reef lights turned on during the day for our corals can help them reproduce, even if we take away all other sources of food. I would recommend trying to get rid of them. Once they start reaching large populations, not only are they unsightly, but I have heard cases of them irritating certain corals because they were all congregating on the coral itself. One of the best products I've used to get rid of them is Salifert's Flatworm Exit. A little pricey, but it is quick and generally gets rid of 90% of them on the first treatment.

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