I'm honestly not sure and I don't want to lead anyone astray.
Up until that intelligent leg failure threat I hadn't seen anyone else fail with that brand.
I spoke with the user who spoke to the vendor directly who is selling PC product and they said that it was nitrate, even though the bottle says nitrite.
I'm not sure if they've changed something around because of everything that's been happening or what.
I'd recommend at least trying to get the aquarium strips and do the nitrite test if you can to check the levels or whatever.
Also with the whole blood test thing, I'm not sure if NITRATE turns your blood brown or not. If it does then I guess that can be another issue and cause confusion. From what I'm aware from Reading threads several people have used it in the past. Never seen them log back on or anyone have troubles with it until IntelligentLeg.