Root tablets are very helpful. Are your plants in any kind of fertilizer (Eco-complete, Flourite, potting soil)? If they are just planted in sand or gravel, that's probably why you are having there troubles.
What is your lighting like, do you add any additives or dry ferts, do you have CO2? These can all relate to why your plant is doing badly.
I recommend adding the tabs though.
Flame - Red and Blue Veiltail Male
Oswald - Blue Halfmoon Male