Thanks nonyabiz for your advices.
I believe your experience in indoor pond will be similar to my setup except for the volume of water.

Currently, my concern is the two live plants I put in couple days ago. The tub only gets diffused sun light. They many not survive to low light condition. And I am planning to put a dish of lava rock on the bottom for the plants to take root.

I browser through some postings in the live plant forum and I kind of worry that if I focus on the plants, like adding fertilizer and such, then my goldfish will suffer.

What is your exprience with planting in in-door pond?