What are these

[Reeflix]

Do you think if I just pulled all my sand out and replaced it with new sand, then treated with fwe would that suffice

i would not take out and replace the sand, they is so many good organisms in there!

 

[Red_Beard]

How do you go abouts that?, most of the ones I pull out are like 1/2 inch but I do have one that’s like 2 1/2 inches I tried to get him out but it just retreats into the rock right when I put my hand in

Check this article out, cheap, effective.
DIY Bristleworm Trap

 

[kjkszpj9]

They are definetly red planaria cause they got 3 tail endings compared to other flatworms that usually have 2.

 

[marktheshark87]

Free clean up crew lol!

They don’t really pose a threat to anything in the tank do they? Or will they bug my nudibranch

 

[Cichlid Dad]

I don't know about nudies, but I have no issues with them

 

[kjkszpj9]

They don’t really pose a threat to anything in the tank do they? Or will they bug my nudibranch

Red planaria dont eat corals or anything but its that they multiply fast and can eventually smother corals making corals get less light which in turn can hurt or kill corals