Start low, gradually increase at a low rate, then if you run into nitrates suddenly dropping and bottoming out, or you start seeing cyano/dinoflagellates, back off the dosage, wait a week or two, and then start ramping up again if they've gone away and your nitrates are again rising.
I'm basically dosing the same way as described above, started at around 1mL/day on a 45g tank that is heavily fed and stocked, slowly ramped up, and then found myself with a cyano bloom and some dinos, ended up cutting back quite significantly, and my optimum dosage seems to be around 3mL a day right now. It may even be wise to slowly increase the dosing until your nitrates drop to the desired level, then immediately cut the daily dosage by 1/3 or 1/2 to a more maintenance level, but I haven't personally tried it - it just may be a good way to dodge cyano/dino issues.