IMO, just keep on dosing. I assume 30ml was not randomly selected. If you increase it beyond "recommended" just go gradually.
VERY IMPORTANT: in my experience of dosing nitrate (NaNO2 in my case) my already low PO4 went zero. Fast. The corals will hate you for it too. Took me a while to match dosing (trisodium phosphate) to keep a steady relationship between the two nutrients. I don't know if it works in reverse (dose PO4 to lower NO3) but at least in two of my systems dosing nitrates lowered PO4 every time.
I'll take cyano and some green algae over dinoflagellates every day of the week.
Disclosure: the whole reason I got into dosing nutrients was a nasty ostreopsis battle.
The 30ml. was my starting point based on my water volume and where my No3 was , reading other threads and looking at the reef calculators i should be adding more to bring my No3 up to detectable levels but i did not want to start high as i have read the same thing that you mentioned about lowering Po4 as well ??
Now my Po4 was already low but again i do not want to do too many things at once so i can try and monitor the changes and adjust accordingly ? my corals do look better as far as color and look like they are still growing , i have not checked my Po4 since i started adding the No3 , my goal is to add more fish gradually and stop dosing No3 .
I started adding No3 as my corals were growing but very slowly and they all looked pale , some looked better than others but within a week of adding 30ml daily my corals look much better , now how do i get the balance to maximize growth and color ?