If you can still see the root tab-your gravel is too large in diameter to use root tabs. You shouldn't be able to see the root tabs once you cram them into the substrate-otherwise, too much nutrients and the root tab itself gets in the water column and will cause problems.
What I would recommend-deep vacuum to get as much of it out as you can.
Most plant problems are due to the wrong color temp bulb-when its not related to old bulbs, improper planting, poor light penetration, wrong photoperiod, non-aquatic plants. Some plant problems can be due to a normal leaf change over-from above water leaf growth to underwater leaf growth...emersed-v-submersed....
How big is the tank, type/size of substrate, how deep, type of filter, how many and what species of plants and how planted.
Lights-what type, age of bulb, watts, kelvin and photoperiod.
How long has the tank be setup and plants planted-also what is the stocking and any ferts used-other than the root tabs