A cap full is 10 mL. The recommended initial dose is 10 mL for a 20 gallon tank thereafter it is 10 mL for every 100 gallons, so you dosed roughly 4x the recommended dosage. I've found that plants start to take damage after roughly 2 times the recommended (initial) dose (or more than about 4x the daily dose). I'm betting that is the source of your plant damage.
Be careful with excel it is a fixative and cross-links proteins.
Jeff, I am compiling an online database of plant diseases, injuries and other problems and I'd like to add these pictures to it as examples of excel damage, can I have your permission to do that? You'll get full credit.
OK well one plant dead for sure the big leaf one on the left broke off at the roots , and when I do a water change I see a slimmy film on the glass , when I do my other tank dont have that. not sure if I should keep this tank up and running or not everytime I plant it everything starts to die
Well took all plants that were still living out of the tank and put in a bowl for now and they have stopped dieing are looking better since removed them . The plants will be replanted in my fluval spec v with new plants that are coming in , so that tank will be heavy planted after getting all plants so it will be awsome