ID help please

[iron_mike_gt]

So these buggers just showed up one day and they spread like bamboo. They really like to attach to rock and my only option thus far has been hand removal. There's some growing out of rock at the back of my tank for which hand removal hasn't worked very well.

Any idea what this is and if there are any natural approaches I can take to permanently removing it?

 

[mborn]

Halimeda. It usually stops spreading with lower nutrient levels.

 

[iron_mike_gt]

Halimeda. It usually stops spreading with lower nutrient levels.

Thank you. That's it and I'll just be patient picking it while I get my params back in check.