[robinscp]

Guys I have being battling this for 4 weeks.

Let me start by saying that It has not all gone but is miles better than it was and I am sure it will go soon.

I started by the usual things I would do with algae issues, reduce nutrients and change water for new nutrient free water.
I reduced feeding, added extra flow and did some crazy amounts of water changes while sucking the snot off the substrate.
I increased my phosphate removing media.
I also added a 200 micron filter to try and catch the slime but it just passed right through.

Adding more clean up crew would not work either as it was killing anything that ate it. (toxins)

The above routine would successfully get rid of cyanobacteria but did not work with Dinoflagellates.

Turning off and reducing the light cycle slows it down but as soon as I put the lights back on it would just start where it left off.

So these things never worked. So what has?

The turning point in this battle was adding a UV purifier.

I believe that because Dinoflagellates is in the water column it is being affected by the UV.

What is happening now is the UV is clumping the dino together so that it is caught in the 200 micron filter and taken out by the skimmer.
I am emptying the skimmer cup once a day instead of the normal twice a week so it is taking something out. Also the filter sock is getting blocked in two days. it never got blocked in the week before I added the UV.

So to get rid of Dinoflagellates I would suggest:
Putting a high wattage UV on the tank and also a filter sock to catch the snot.
I would also add a lot of carbon to the tank as this reduced the smell and I believe reduced the toxicity of the dino. (I never lost any more snails after adding the carbon)

I hope this helps anyone else that may get this problem.

Cheers