They're not going to die anytime soon don't worry about that. The new growth looks good. Old ugly leaves just get older and uglier, the plant is using the nutrients stored in them to power the new growth.
Measuring run off isn't that important. There's a big difference in the first couple drips that come out to the last few.
I only worry about what's going in. Water to run off, more is better, but there's no point in wasting it. The whole point is you want to rinse out all the old nutrient solution and replace it with new stuff. The medium is fully soaked by the time run off starts, another .25l won't hurt but it will help insure all the nutrient solution is fresh.
3 liters is almost a gallon and seems heavy for a normal watering. I use about a quart ≈ a liter for my one gallon containers.
You've got leaves very close to the top of the medium, I cut those off after the plant has a few sets of fan leaves so the top of the medium dries out better.