Your light equals almost exactly my wpg...so that ain't it.
Do you have any calcium built ups on showers? That would indicate hard water.
My pH is 7 so that ain't that far off neither....
I'm sorry hun I know I been reading and replying a bunch to you, but with I donno how many other posters I help every day, its hard to NOT mix up in my head who has what tank set up, sorry for that
You just said 'didn't work'...like how did it all turn yellow or did it turn brown?
The only other thing that comes to my mind is lack of CO2, cause I read numerous times they're CO2 hungry (which is why up until recently I never attempted these plants) - Means your stock vs plants...do you have enough fish in there? Or maybe use Excel?
One more thing that set's us apart and when the dwarf baby tears started taking off for me: Lights, when I set them to 5 on 4 off 4 on; I'm assuming your runs all the time ?