Ok. So the Tiger Bloom at 3 teaspoons per gallon was their limit. I gave them the usual 600mL that I always do only this time I noticed very slight browning of the tips of the fan leaves. This instantly made me aware that I had reached their feeding threshold and should not increase the ratios anymore. I am now dilluting 300mL of my solution with 300mL of plain water to reach a consistency that the plants are happy with. No furthur burning or browing has occured since, so I have figured out exactly how much nutrients they can take.
Urdedpal was dead on as usual. The Tiger Bloom burns easily, and I recommend NO ONE use the 4 teaspoons per gallon or "Heavy Feeding" option unless it is your sole source of flowering nutrients.
However I feel experimentation is best. The plants are now doing even better because I have found the maximum amount I can feed them, and because I was careful about it, no major damage was done.