Dear Shannon,

If you haven't alraedy, might check out www.firekasina.org, as that will tell you a lot about the practice.

In terms of water, I would pick a bowl of neutral color or just plain glass about 4-6 inches wide, fill it with water, and might add some blue food coloring to get it bluer. If you are able to find a glass bowl, might backlight it with something, like an LED light, such that it glows blue, as things that glow are easier to get afterimages on, and better afterimages lead to better images. Doing something like this to get elemental balance is a great idea, as, while the fire kasina retreat we did was great, still, I could tell that we needed to round things out, and not doing so produced some strange effects.

I would also realize that doing this is likely to lead to some pretty strange experiences, and you might find someone to talk with about them if and when they occur, as weirdness of mind is not only likely but expected in some ways, and some weirdness is good and some is not.

I would do a few days of candle flame to start, then do a few days of water if you are able to get good images on it, and alternate that way, so that both have some momentum and you can really get into each. Might use a mantra suited for each that is different for each, and ask for formal connections to the elements when you do this, as intentionality helps.

Best wishes, and let us know how it goes if you so inclined.