There are indeed many plants sensitive to liquid carbons such as Excel. Anacharis is indeed one such plant.
Liquid carbons are used daily as they only stay in solution between 12-24 hours before being totally broken down. Since I am and have been a big user of only liquid carbon and no CO2 for a very long time I have found it varies with each individual tanks chemistry as to whether certain plants can be desenitized to using liquid carbon. I have a large stand of Corkscrew Vals for over a year in the 220g that gets a high dose of liquid carbon daily and I've never had any melting issues, yet others have thiers melts. The best way IMO is to start dosing 1/4 the amount of daily liquid carbon, do for 2 weeks and see if there is any change in the plants, if not go up to 1/2 dose, and continue until you reach full daily strength. If at some point the plant begins to show signs of melting then back off the amount to the dose you found worked.