Your water is moderately hard, I would say. Is that 250 ppm for GH or KH? You need to know both. Divided by 17 gives 14.7 degrees of German hardness, but which one? If it's KH, then I can see why you switched to a pressurized system for that size tank. Plants take time to grow especially when they have been nutrient deficient (stunted) in something, then it takes a bit longer to visibly see a difference. You gotta have patience or you could add some new plants that haven't been lingering at the LFS.