Water Gardening: Lotus flowers browning , 1 by ardesia

ardesia wrote:
My 'Sweetheart' Lotus flowers are drying up and browning before they open. The petals are thin like tissue paper. I have never had this issue before and am loking for possible causes. I have checked and can find no indication of any mites or any other pests. The leaves are fine. This is the first time I am growing this cultivar and it was a new plant this year, planted in fresh soil. Any thoughts?

Sorry this is a fuzzy pic, I'll try and get a better one later.