Bill,
The biggest challenge of overwintering indoors, in water, is that the water can become foul. While I'm not overwintering lotus, I am overwintering a tender pond plant in the basement. I was told to make frequent water changes and discard any declining/rotting material. After awhile (a month?) everything becomes balanced and the frequent water changes are no longer needed. It was recommended to keep the plant cool in a bit of light to promote a semi-dormant state. I'm going to up my success chances by adding an aquarium bubbler to oxygenate the water and, maybe, add a little peroxide.

I'll attach the thread that contains the information. About a third of the way down "Dave-in-Nova" writes about the procedure. In another post he said it was similar to the way he stored lotus.

I'm quite intrigued that you started lotus from seed. Do you have any pictures?

Gail

Here is a link that might be useful: Overwintering info lower in the thread