I've been I the hobby about 7 years, and I've always had success when with a more natural approach. Whenever Ive had these issues it's usually because something is off with the beneficial bacteria to cyano/dino population balance.
It sounds like you have a lot of good advice so my 2 cents, but I'd do a 50% water change, with a small siphon tube to remove as much of the nuisance as possible manually. I'd then add a bacteria culture (I like microbacter7 but there are a bunch of good ones) and if you can find it live zooplankton cultures. This will help try to outcompetes the nuisance algae, which yours does look like cyanobacteria. (Careful with the zoo plankton, it can lead to hair algae if you overdose, although Id rather deal with hair algae over slime algae)
I got this advice from WWC in Orlando when I lived there and it always worked well for me when my tank was off.
Good Luck!
It sounds like you have a lot of good advice so my 2 cents, but I'd do a 50% water change, with a small siphon tube to remove as much of the nuisance as possible manually. I'd then add a bacteria culture (I like microbacter7 but there are a bunch of good ones) and if you can find it live zooplankton cultures. This will help try to outcompetes the nuisance algae, which yours does look like cyanobacteria. (Careful with the zoo plankton, it can lead to hair algae if you overdose, although Id rather deal with hair algae over slime algae)
I got this advice from WWC in Orlando when I lived there and it always worked well for me when my tank was off.
Good Luck!