From my personal experience tanks where sword plants did well in had to much light for Crypts. And vice versa. While i run 80 watts of power on my 50 gallon Sword tank for 10 hours a day, My Crypts only get 20 watts of light but for 16 yours a day on a 29 gallon tank. This might varry with the type of Crypt but from my experience they like low light for a lot of hours. dennis