If you ever dosed any algaecide like Vibrant, AlgaeFix, etc. then people are struggling to keep chaeto even long while after not dosing anymore.
I have seen too many tanks, including some of my own, with macro struggling in the 25-50 ppm of no3 range and then full out struggle over 50ppm. The proverbial "I have 100 nitrate and no algae" type of deal. po4 plays into this too.
Carbon dosing is a long term, daily thing. Go slow, keep at up and slowly raise the dosage. Your skimmer cup should be the first thing to watch. The skim mate should change, smell totally foul and rancid with hugely increased production. When all of this starts to happen, freeze the dosage. Don't keep raising it. It will do the work over time. There are many articles on this that you can read. I used just plain old sugar in a FOWLR with good success and after I got the nitrate down to about 20-25 some GHA started to come back... then I got it down to like 1-5 ppm and the coralline started to take over again. Vinegar, vodka, sugar and ethanol all have supporters and also detractors, but in the end, they all work. Growing bacteria with organic carbon does not appear to use orthophosphate, which is the only kind that we can test for. It has to use other kinds or else organic tissue cannot form, so pay close attention to your corals, if you have any, since they likely use these other kinds too. Just remember that high tide lifts all ships, so other types of things will grow more too.
