Lotus growing help

[tomwww]

i am trying to grow some lotus plants for my koi pond and the sprouting process was simple enough , i planted them in a little pot in a kid pool in my garden. i used soil from my garden, added some chicken poop as fertilizer and toped it off with a thin layer of gravel to stop the soil from leaving the pot. my lotus started to grow really fast but after two weeks the leaves started to turn yellow and die. so... any tips on howto save them.