I never mind questioning

I'm getting product from a reef brand I have immense trust in to try out in this regards and I'll only be using a small amount for some baseline type dosing too.
I agree, there's definitely ways I'd rather go about this for sure but given that I can't add fish or feed the fatties more than I already do and I can't really have the skimmer off, the dosing is the simplest/best way to do it for me at this stage

this isn't planned to be a long term thing but more of a temporary fix till I can more fish in the tank to bring up the bioload
With my current little system and low fish load, I'm having to dose NO3 and PO4 as well. I have some fish in QT to bring the bioload up, (freshwater Mollies that I've been slowly acclimating to salt water), but until then, I'm having to dose almost daily.
These guys have excellent products and they're quite reasonable
https://greenleafaquariums.com/categories/aquarium-fertilizer/macronutrients.html
Dont know if you can get their products in the Land of Oz or not, but I've been using their KNO3 supplement for several years now (same 1 lb/0.4535924 kg jar the entire time).
I know you're still using filter socks, but have you considered a filter roller?
I'm liking the little Bubble Magus filter roller I have. Whole lot easier than changing out filter socks every other day and this way I dont get yelled at by the wife for putting them in the clothes washer.
If you want to add some harmless fish that just swim about the tank, nibble algae, and dont fight with anything or do any damage to the corals, you might strongly look at converting freshwater Mollies over to salt. They are substantially less expensive than saltwater fish, can be purchased pretty much everywhere, and wont bring diseases over from freshwater to your reef.
They arent particularly attractive when compared to what is usually kept in a reef tank, but they serve a couple of different purposes:
Eat algae
Add bioload without eating/harming coral
Good dither fish to get new fish acclimated to the tank without aggression
Kinda wishing I'd figured that out earlier and used them as a dither fish for QT over the years.
Just random thoughts while I'm on nightshift and drinking coffee...take them for what they're worth, (which isnt much).