I've used algaecide and will share my experience. I had terrible diatoms and green hair (thread) algae. Most likely because the tank was newly setup - only about 3-4 weeks. The inhabitants were 10 amanos, 10 tetras and 7 raspboras.
I applied algaecide Dr Tank Algae Control Zym. Yo have to google it - its a Chinese product. I'd likely be criticized for it - but this is my experience.
Applied according to dose - the fishes were fine - all survived. But I lost one Amano - would have lost 3 if I hadn't remove them and placed into another quarantine tank. The two recovered so I placed them back.
The algaecide was very effective though, because by day 3, all the thread algae and diatoms were all gone. The cost was one shrimp.