I recently got an amazon sword. I knew it needed root tabs but I couldn't find any. Instead I've been using liquid fertilizer. I've been following the instruction and putting it in as often as I safely can (.25ml twice a week). I have gravel as my substrate so the water can reach the roots. My anubias has been doing great but my amazon sword is growing extremely slowly (if at all). Should I look for root tabs or will the liquid fertilizer be enough?