Hello, I may be wrong but the crypts leave looks fine, some crypts can grow brown leaves like my petchii and some of my wendtii. It's hard to say but it does not look like algae.
The java fern leaves which looks bad maybe just old leaves that should be cut. Are there new leaves which look healthy?
Careful with Excel, pour the recommanded dose, do not overdose, unless you are looking for a particular result.