I would do a major water change. I do not believe any snails will eat that. What source is your water from? If you were here in the U.S. I would assume you used tap water. You have way too much phosphates in the water. I would balance the tank with either a canister filter or hang on back using Chemi-pure. Here's a link. I use to use this when I had salt water aquariums. Once it cycles you can remove it. OR start all over.
Yes I started with tap water and have done some water changes with ro water and it's still coming back. I have mangroves in the tank so I had to keep some type of light on. I guess I can move the. I was suggested using chemiclean and I can probably use chemi pure in conjunction with chemiclean. I might have to get another tank going pretty soon coz I can't stand it anymore.
I had the same issues years back when I had set up a salt water reef tank. Instead of using my LFS salt water I decided to mix my own using tap. The local water here has way too many impurities and I had the same issue. The positive side for me is I also ran large canister filters so it wasn't too difficult to add chemipure to the filtration. I would suggest as Odin stated start out all over unless you can filter the water of the phosphates.
That's what I'm about to do. Someone suggested that chemiclean is ok but it's a temporary relief. I will I have a smaller tank started last night with just ro water. All the shrimps seems to be all doing well. It's just ugly.
Great to hear you're going to start all over with RO water. You'll be fine. At least you have an answer to your options on what to do. Good luck. Keep us updated.
I used to have a blue-green cyano problem and “Easy Life Blue Exit” was effective in ending it. However, I don’t know if that works as well for pink cyano. Try to look out for chemical treatments that are marked as invertebrate safe.