Pure waste of money IMO. To us plantedtank folks, seachem excel and other glut based products is an alternative source of carbon for us. In the dry world (don't ask), we got the air which contains carbon. I've read online that some have used it to control fungus/other unwanted growths; but with many [cheaper] products out there to fill that purpose, excel is just a money pit.
As for the rest of the seachem line, it's also a money pit compared to other fertilizers that are meant to be used for terrestrial plants.