I'm a newbe at live plants and it seems they are not growing. I have a Amazon sword and two others I don't know. One is floating strands held down by lead wieght. Hornwort? Anyway they seem to look fine but no growth to speak of. I have had them for a couple of months(not the "hornwort" 3 weeks). My PH is 7.6 - 7.8. Maybe too hard? Need plant food? If you have any suggestions please let me know. Thanks