Everything eats cyano, problem is, it grows too fast.
I'd suggest doing the easiest first.
1) check nitrates. If they are high, get them down - particularly if you added bioload recently.
2) check lights. PCs, for example, typically are shot by one year at 10 to 12 hours a day.
3) Only worry about water flow if you've changed the water flow recently.
4) Add some critters if you want, but they aren't going to keep cyano in check if the nitrates are high.
Good luck