If you want to remove algae from live plants, use a clean sponge and rub off the algae with it. You will be up to your elbows in tank water but I have never seen any adverse reaction to me doing that. I sometimes need to deal with a hair-like algae growing from plants and everything else in my tanks. I simply reach my hand in and grab the stuff to remove it. I have some rainbow cichlids in one tank that love their veggies so I carry the stuff to their tank and chuck it straight into that tank. It never lasts much more than a day with those vegetation pigs eating it. Nor does any other plant that I give them.
