Well, i just needed to clear some hair outta my rotala... api is a 4.6 % concentration.
i used tetra's brand. its 5.4 % and it says same dosage
i have around 36 gallons with my sump total volume. i put 4 ML in and fish/ plants are fine 3 days in. ammonia has't spiked.. so 1.5-2 x the reccommended amount would be a SAFE place to start i would think