I am looking for some grape caulerpa ( C. Racemosa.) please let me know if you have some. My Chaetomorpha no longer does well at the low nutrient level.
https://www.live-plants.com/ usually has it... but they're showing out of stock at the moment. They are showing C. Prolifera in stock... might be something to try. Less likely to spread to the display tank than C. Racemosa is anyway.
I have C. Prolifera. It does not crumble and die like Chaeto, but it does not grow fast. I had C. Racemosa before and it worked well for me. It is getting hard to find them locally.