Is this a coraline?

Don Golde · Jul 4, 2019

Bryson.bobby said:
It also depends on what species of flatworms you have. Some will eat corals and some won’t (I believe the white flatworms are harmless)

Edit: here’s a thread on acoel flatworms
https://www.reef2reef.com/threads/white-flatworms.85789/

Mine are red! dangit!

Softhammer · Jul 5, 2019

Those big tan ones are harmless. Just a major annoyance and irritant. It’s the tiny ones that destroy your corals. They are a major indication that your water quality may be a little dirty. Siphoning, which necessitate water changes and a good skimmer will keep them in check as well. Also be prepared for a wrasse to do nothing. Your tank is on the small size for a Halichoeres wrase which is what you need. Salifert flatworm exit does appear to be available still. I have used it quite a few times in the past and it works great. Especially on small tanks. Hit it with a dose, follow directions, and then a water change (siphon all you can see out) and run carbon. Piece of cake.

Don Golde · Jul 5, 2019

Softhammer said:
Those big tan ones are harmless. Just a major annoyance and irritant. It’s the tiny ones that destroy your corals. They are a major indication that your water quality may be a little dirty. Siphoning, which necessitate water changes and a good skimmer will keep them in check as well. Also be prepared for a wrasse to do nothing. Your tank is on the small size for a Halichoeres wrase which is what you need. Salifert flatworm exit does appear to be available still. I have used it quite a few times in the past and it works great. Especially on small tanks. Hit it with a dose, follow directions, and then a water change (siphon all you can see out) and run carbon. Piece of cake.

And I'm changing 4 gallons every 2 weeks. Maddening!