Mortadelo,
What an improvement in aquascape from previous tanks. I'm glad that you went with slope effect and left right side empty. Really works in this tank. I would work a bit more on substrate cover. Is that Marsilea sp. ? Doesn't look too healthy or is it just the picture ?
As for as Gratiola/Limnophila question.
Look into
THIS !!!!!!! topic for additional information.
Good job.