Best to get a doser. Drew's dosers are perfect because they're a 4 roller @ 1.5 ml/min.
Makes it super easy to dose a single drop or more, but it adds stuff slowly enough to avoid spikes.
Best you can do though is get the doser, then start low, at like 1/4 the dose suggested by red sea. Wait a week, then adjust.
If you see nitrates bottom out to 0, cut the dose by 75%. Wait a week, then reevaluate.
May I ask, what frozen food do you feed? Is that all you feed? Pretty surprised by the ratio of nitrate:phosphate you have going there. (or do you run gfo?)