Hi,

I battled dinoflagellates for four months. My tank is running on the full Zeovit method for about 16 months now, I was in my eight month when it started. I only dosed Start2 and Bak (both reduced by 50%), everything else I stopped. But I assume you are not dosing any Zeo products now?
- No water changes.
- Drip Kalk to maintain pH of 8.5
- Run filter socks(25 micron) on all drains- changed daily
- Carbon (passive) and GFO (low flow)
- One day of darkness every three days, lighting schedule was also reduced to only two hours of full light, supplement eight hours.

In 28 days it was all gone. I can't say for sure what exactly was the contributing factor in the eradication, but I think all of this helped.
I personally would not bother with a clean up crew, snails anyway, as dinoflagellate is poisonous to them. Wait till the dinoflagellates has fully gone then add a new CUC.

Hang in there, it just takes a lot of patience.