What standard operating procedure?
There is no real "standard", but there is a variety of things people attempt.
1. Nutrient control
If nutrient levels are low (near or below the detection limit of test kits), e.g. 0.05 ppm PO₄ or below 1 ppm NO₃, people add nutrients by dosing DIY solutions:
Nitrate and ammonia dosing both provide nitrogen. Ammonia is usually the better choice, but I have heard reports of people whose problem was solved by nitrate dosing but not by ammonia dosing, so try both separately.
If nutrient levels are elevated, use water changes for nitrate and granular ferric oxide (GFO) for phosphate.
2. UV sterilization
Heavy UV sterilization is another approach people take. Putting the UV sterilizer in the display tank might be the most efficient way. Make sure the unit is even a bit "oversized" for your tank and that the attached pump is adequately sized. In severe cases, and for dinoflagellates that don't seem to leave the substrate much, you can try out the
UV Sweeper. But when you see a significant difference between day and night in the amount of mucus, this
might not be necessary.
Some people try a blackout for 3 or even more days to get dinoflagellates to leave the substrate and end up in the UV sterilizer. Some report success, others say the dinos come back afterwards.
3. Silicate dosing & Diatoms
Then there is the approach of silicate dosing.
@saltyfins mentioned using sponge xl, but you can also use a
sodium silicate solution. This encourages diatom growth, and diatoms are supposed to compete with dinoflagellates for nutrients and surface area. This approach doesn't always work, but it's worth a try.
4. Manual removal
Manual removal can feel exhausting and ineffective, but it certainly helps give other organisms a chance to settle on the surface area dinoflagellates have taken over. It's a long process, but it was quite certainly an important part of many success stories.
5. Bacteria dosing (Experimental)
The use of bottled bacteria is somewhat controversial, but some people report success, so you can try it. People use bottled bacteria products like
Tropic Marin's Nitribiotic to stock up on "good" bacteria, hoping they compete with dinoflagellates. Considering the phagotrophic capabilities of some dinoflagellates, it's always hard to tell if this is just feeding the dinoflagellates or actually helping.
6. ORP control (Very Experimental)
Adding ozone to the skimmer is nothing new, but it has become quite rare, so not many skimmers support it anymore. If you have one you can use it with, it might be worth a try. Another possibility is dosing hydrogen peroxide in small amounts. This doesn't have the same effect as ozone, but it has also been reported to "work". None of this has been scientifically verified, so it's very experimental, and sometimes corals don't appreciate the ORP change. The only reason I can think of why hydrogen peroxide or even bleach dosing could have an effect on dinoflagellates is that trace elements get oxidized, which could make them less available to dinoflagellates.
I hope I didn't forget something. Either way, pretty much nothing has been shown to work 100% of the time jet, it's all anecdotal.
