The Fluval Aqualife and Plant LED was the companies first entry into the planted led field. It recently has been replaced by the more powerful Fluval Plant 2.0 led light. What frustrated hobbiest such as myself, was the lack of published PAR data for their first entry. Please refer the thread I started in 2013 regarding this-
http://www.plantedtank.net/forums/10-lighting/312713-new-fluval-plant-led-no-par-data-available.html
You will learn alot about your current light by reading posts in this thread. From what I can tell, based on PAR data appearing later in the thread, your light would provide medium at best lighting. Based on comments later in the thread, persons were having having success growing and maintaining their plants. With the 18.5" front to back of your 75 gallon tank, you would want at least two of the lights.
Here is information about the new Fluval Planted 2.0 led light-
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=32451
Please refer to the PAR data. With these new lights, you could obtain 80+ PAR values with your aquariums depth (accounting for at least 3" substrate). This would provide for high light plant options. I believe you would still need two of the lights because of your tanks front to back diminsions.
Hope this helps.