I decided to go above the max recommended dosage since my nutrients continued to rise, and I see no adverse effects to fish or invertebrates, and am now at 6ml per day. My NO3 and PO4 are holding steady right now at 37-38 NO3 and 0.78 PO4. I've been diluting my tank water to see my true PO4 level, since my Hanna checker maxes out.
I did notice when I checked my PO4 midday after the dosing cycle, rather than my normal 6am testing time, that the reading was about 0.1 lower. See the dip in the PO4 chart below. To maintain more consistency, today I started spreading the dosage out over 24 hours, rather than my usual morning window of 7:30am to 1:30pm.
Also, as shown in the PH/ORP chart below, these parameters were being yanked back and forth during the dosing time period. PH dropping 0.07 - 0.10, and ORP spiking 80 - 100. Spreading the dosage over 24 hours should smooth out those charts too.
Please let me know your thoughts.