If there were an algaecide available which would kill off algae without harming the plants or fish, it would be one of the most sold substances in the aquarium trade. You can be pretty sure such a material is not available. Excel comes close to being an effective algaecide, but at the concentrations where it actually kills algae, rather than just inhibiting it, it also kills some plants, and is in the range where the constantly emitted fumes from the dosed tank would not be healthy for humans to breathe every day. When we use Excel to kill algae, it is by directly applying it to the algae, not by routinely dosing the tank.
Potassium Permanganate is a great algaecide and is safe for your plants but not so much for fish if you get more than 2ppm which you need to do. The same oxidizing agent that kills algae will attack the cell lining in gills so you have to be very careful or take the fish out of the tank while you work on it (that's what I do).
I use Excel for light cases but PP for anything short than breaking the tank down. I just remove the fish first but then I'm not resistant to doing a bit of work.
I have tried algaecides that said they were plant safe, and they were not. The worst one I tried was Jungles' fizzy tablet style, I forget the name of it. It said safe for both fish and plants, so I dropped the recommended dosage into an 80 gallon semi-planted angelfish grow-out tank and several hours later, I had dead fish, dead plants, and healthy algae.
All antibiotics will un-cycle your tank because they kill off the beneficial filtering bacteria as well as the disease causing kind. As far as antibacterials, I use Melafix and Pimafix regularly without any problems to plants or good bacteria.
It's all about dosage and ppm I use PP without any problems but then again I understood my high school chemistry classes way back when. The problem with those drop dead simple commercial products it that you can't control the dosage and you end up getting something unexpected at times.