I’ll add a bit more to go with what Paul said. Say you add some chemicals to kill this algae. Well that material just got converted back to something. It didn’t get removed and plus you got whatever was in that chemical in your tank as well. When you have a well lit refugium algae will grow there instead and when it accumulates you can easily remove it thus removing contaminates from the tank naturally. Your tank is telling you something by growing algae like that, it’s saying there’s a bunch of crap in my water and I need to get rid of it. Lol. And the only way it can is by growing algae. You Harness that natural process when you add a refugium of some sort to your system. Add a big enough one with enough light and it will eventually catch up to the waiste in your system and keep it all cleaned up. The only other way that won’t eventually lead to a crash is tons and tons of water changes. But that can get expensive and isn’t nearly as good for the tank. When you got a big refugium tied In you’ll be protected from such nasties as amonia too. Algae is nature’s way of removing toxins.