The simplest solution is a series of water changes but you need to make sure the water you are using is 0 TDS RODI to make the new saltwater. Then do a series of 20% changes and that will bring nitrates down. 10% is better if you have corals etc so the parameters aren’t affected as much.
The other options include increased levels of biological filtration such as adding Seachem Matrix , De Nitrate, Marine Pure etc etc, and then their is carbon dosing such as Nopox or vodka as you mention
You have to balance nutrient import with export and have enough systems in place to keep the levels down (I know!) and once set up it all works with very little intervention from you.
Or maybe get a bigger refugium if you can or a combination of all of the above.
I use most of these methods combined as I have a massive bioload!