I'm fairly sure there is no absolute UV immunity. Dinos vary in UV resistance and can recover from damage, so contact time and exposure need to match.
This is going to be controversial, but: I'm always astonished how sure people are about their method, even when it's based on just their tank or verifiably flawed hobby "knowledge".
- Day/night migration isn't black and white. Cells are found 24/7 in both plankton and benthos (e.g. Pavaux et al., 2021). @RobertK and I verified this in tanks for Ostreopsis cf. ovata (identified by thecal plate structure), and also some cf. Amphidinium. "Coolia" and Prorocentrum are pending. Cell density obviously still differs and affects UV susceptibility.
- Toxicity depends on strain and environment, so it shouldn't be attributed to a genus (e.g. Tartaglione et al., 2017).
- Besides Amphidinium, some tanks very likely have Testudodinium. The "LC Amphidinium" in a document from Mack's Reef is most likely Testudodinium cf. maedaense. Paramphidinium might be present too, yet people treat them as the same thing.
- Coolia is also hard to distinguish from other spherical benthic dinos, so different genera may be involved here as well.
Nutrient dosing doesn't work in every tank, but in some. In mine I can reliably start and stop dino growth with it. In theory nutrients should feed dinos, but it also shifts nutrient ratios and may change the periphyton, which I suspect plays a major role since we are talking about benthic species (credit to
@Dan_P for that idea). The periphyton could explain why dinos sometimes stay in spots seemingly incapable of spreading to other spots. Verifying or refuting that theory will unfortunately take quite some effort so until then, take this with a grain of salt
I think we should move past "my approach works, yours doesn't" and "high/low nutrients/flow/light is the cure". If something works in your tank, great! But the many examples here on R2R show these "treatments" are hard to get right, and some just might be ineffective depending on the tank or dino species. Let people test various approaches until one works for them.
Good comments but still some comments on the comments:_)
When we have a situation/disease, where we cant theoretically explain or understand, then the practical experience has higher impact of evidense. I know some disagree about this, but I still persist what I tried to say in the "scientific thread", that we sometimes give too much trust in scientific studies, or lack of studies, and less to practical experience. At least in those cases where the theory struggles to explain the reality. Also, the consequences are severe when coming to dino, meaning you have not time to do too many tests that may be very hypotetical. Its in these situations we are logic and prone to rely what we see, observe. I have had dino and struggled versys dino for 25 years, and seen and tried all methods with more or less no success. So for me when I suddenly do something that 3 times repeatable gives 100% results its not unscientific to say, this is very likely to work also the fourth time. All these threads are a reflection of that many methods just dont work.
Its no ones purpose to be right, we just try to help each other.
But, also concerning the UV discussion. I think its clear that with proper dose and contact time, UV kills every Dino despite specimen. When I read these threads many uses UV in the wrong way, and then, ofcourse, it will not kill the dino. It was an eye opener for me to invest in a better UV, and followed the specifications that TMC has on its own system.
I will see if I can find some data for this of anyone is interested in the UV method:-)
Jonas
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There is anecdotal evidence for all of these various approaches even if they failed in some tanks (e.g. silicate dosing, ozone skimming or peroxide dosing, manual removal, bacteria dosing, etc.).
