By far the best read about dinos:
https://www.reef2reef.com/threads/dinoflagellates-–-are-you-tired-of-battling-altogether.293318/
That thread covers every type of dinoflagellate. You can even post a photo from your microscope there and get the exact way to beat it.
A few kinds of dinoflagellate are quite easy to beat, once you have the correct ID (like just running a UV). There is one particular strain, the one I have, that is close to impossible to beat.
A few things to note:
1. Dinoflagellates outcompete other types of algae when there is an imbalance or low amount of no3/po4
2. Even reading 0 on no3/po4 doesn't mean there isn't any, just means dinos are consuming them a lot.
3. Dosing more NO3/PO4 will just keep feeding dinos. Once you're at an imbalance and dinos are there, they will not let other algae start growing. One possible method is to add a crap ton of algae (macro or otherwise) that will begin outcompeting dinos. But there's a high chance that trying to feed other algae will never work, and you'll just continue growing dinos because they're really good at competing for resources, especially when well established.
4. Has nothing to do with sand specifically. It's everywhere.
5. Dinos can kill corals by attaching to them. Even more, when they die or are disturbed, they will also start killing stuff. Fish don't seem to be bothered, but weaker snails/inverts would be. My Anemones, however, pulled through but were definitely affected.
The most promising thing I had going was I used DinoX at first to start killing the dinos. It works well after about 3-5 days. The instructions are weird, but just keep dosing and don't run carbon so the amount keeps getting more concentrated until they're all gone. You can then try to grow chaeto and start dosing no3/po4 so that their levels are high and even, and consistent. At this time you can do a big water change + carbon. The idea is that you can grow the non-dinos faster than the dinos can come back and take a foothold. Ultimately it will be a battle of algae. DinoX shouldn't actually kill Chaeto, but some say it does.
At the end of the day, nothing worked for me (6 months or more). My tank was struggling to keep no3/po4 up, and the more I dosed, the more dinos grew. Ultimately someone on BAR just said to go super lean with a scrubber or NoPox and just not let anything grow. So I tried it, and it worked. Now I dose 2.5ml of NoPox daily (using a dosing pump), and I have no dinos anymore. I get a tiny bit of algae but that's feeding the snails well. I do get a white dusting of bacteria? growth on the glass. But everything looks good. I even have decent colors in my SPS now. I do, however, dose Amino Acids (AcroPower, though it could just be snake oil) and I spot feed reef chilli 2 - 3 times a week.
