No disrespect to PaulB but one tank is not an example of the best methods
I agree and hate that guy. I am not even speaking to him.
For some reason a lot of people don't realize that I was a Noob longer than most people here and had all the problems many times, and tried every "remedy or cure", not just once.
I cringe when I hear someone is going to put antibiotics in their tank because I know that is near the end of their hobby experience.
I also cringe when I read of a fish with a spot and the owner tries to catch the poor creature and remove it to "help" it.
I killed more fish than Star Kist Tuna.

So I may know some things that some people are struggling with.
Virtually everything I learned was the hard way way before the internet, way before all the opinions.
I used to quarantine, I dosed copper, formalin, "Red Slime Remover and Chemi Clean" maybe a dozen times.
Those things always worked but is it the best thing to do? The answer is Sometimes, maybe. ;Bucktooth
The problem is that those chemicals will always affect how the bacteria operate and not usually in a good way which is why that is many times the beginning of the end of the hobby for many people.
I don't come up with this stuff because I want your tank to crash.
I moved my tank here to my new home a year and a half ago. I had to wash most of my gravel for the move because my UG filter accumulated so much mud that was mixed with my gravel that I couldn't put it in my tank or you couldn't see anything. Most of my gravel I washed in fresh water because I had no sink or sewer near my tank when I moved.
I also didn't have any seawater or enough ASW so I couldn't rinse anything in that.
My rocks got cold because I didn't even have electricity except for one 15 amp outlet 20 feet from my tank.
It was almost like setting up a new tank except that I did keep my corals and a decent part of my rock stayed underwater and almost warm.
But in that year and a half, my tank exploded with life just from what was in my remaining rock.
Here in this new place I can't find hardly any amphipods . I only added some mud maybe twice from a bay but that is only for bacteria for water conditions and I am not even sure if it does anything.
I have to diatom filter my NSW because I take it from the surf and it is full of sand and chopped up seaweed so it is not clear and looks more like Half and Half.
I vehemently feel that the vast majority of problems people have with their tanks is caused by them.
It is just the nature of the beast because of to many opinions. Most of which come from Noobs with little experience or experience from one of two episodes with that issue or fish.
I had no one to ask and I think I was better off. I tried something, it didn't work, then I bought another fish and tried something else. Eventually I figured it out and now know exactly what to do in every instance. But the most important thing I learned was to do very little if anything for most things.
If you stay in this hobby long enough (5 years is not long enough) You will learn that everything comes and goes in cycles just as it does in nature.
When I was a kid in the cretaceous period, I used to go fishing a lot.
90% of the fish I caught were blowfish with a few sand sharks.
Over the years the blowfish were replaced by flounders, bergalls, porgies and now sea robins. Those other fish, in the places I fished are totally gone.
Where did they go?
I also used to SCUBA dive for lobsters almost every week and used to get my limit every dive.
Then all of a sudden, they were gone with not one lobster to be found. Why not?
I doubt anything we could have done would have kept those species here and I also doubt anything you do to your tank will effect those cycles much.
I do know that they are normal and natural so if your tank "wants" to grow hair algae, it will grow just like cyano will grow. It has nothing to do with pollution, lighting, flow, or nutrients as it grows in all tanks including mine.
It will leave as it always after this cycle that I have no control over.
This is the Crux of the problem in this hobby.
WE don't have quick fixes, nature doesn't work that way, if it did, I would have hair.
Look at this hair algae I had maybe 25 years ago. Most people would have dumped out their tank and got a job in Home Depot demonstrating the leaf blowers in the parking lot.
I almost did that myself, but instead, I did nothing. I realized after much frustration that hair algae is the absolute best water purifier, conditioner and not a disease.
After it left on it's own with no help from me, the tank ran with no problems for years, it still does and I still have that fireclown in the picture.
I then started to realize that much of the things we perceive as a problem is actually a healthy, normal, natural thing.