I think it's time for old school technology, sulfur denitrator, 3 months ago I was at 40ppm, took out denitrator, in two weeks down to 5ppm . Right now at 5ppm, it's been 2 months since stop using denitrator. Again sulfur denitrator
Now we can understand better. If sps are starting to stn, yes nitrate is doing damage.
It is not trace element depletion, but you have something bad in the tank,a toxin that is toxic to certain living things. That is what Vibrant is, combination of toxins that inhibit algae and cyanobacteria. These toxins are also toxic to other living things to a lesser degree. Changing the water only remove whatever in the water. If these toxins are bonded to the surface of the rock, or seeped in the sand bed, changing water isn't going to remove them very easy/effectively.
Here's my two cents. The makers of Vibrant claims that the bacteria culture cannot sustain themselves long term in the reef tank. This highly implies that this bacteria has no place in a reef tank. We also know it is a heterotrophic bacteria and we can assume it attacks algae in some way - it is a predator in a way. If you know anything about ecosystem biology, you would know that introducing a species that has no natural place in the food chain - perhaps they have no predators- ultimately negatively disrupts the food chain. In this case it is a predator with no natural predators in the reef tank. It also seems to be a VERY unsustainable organism in the reef aquarium environment because it apparently doesn't reproduce well in it. This means you are introducing an organism with the sole purpose of disrupting the food chain and ecosystem of your tank - perhaps this means the algae will be wiped out, but more likely you will damage your tank's biodiversity and tank maturity. I think Vibrant is a cop out solution, there are methods that can handle algae problems much better. For exampls, dinos can usually be handled by silicate dosing and nutrient dosing.
It really does not matter what they say to sell their product. They don't list their ingredients. Their product wipe out one or more living organism (undesirable living organism) when added to your tank. At the very least Vibrant wipe out various algae. That is what it used for. That means it is toxic to that organism therefore a toxin.
It's not a stretch at all. There are bacteria that release compounds that will cause algae cells to die in a process called apoptosis. Using bacteria that produce algaecides that are essentially toxins to algae are a known thing - it has been used to control dino blooms in the past in lakes.
