Agave Nectar would be pushing it, Oliver. From what I hear, sugar is an important constituant on which the organism feeds. That is it's food. So, if you want to EXPERIMENT and let us know, it may be wise to begin with turbinado - unrefined sugar.

The sugar really won't matter in the end. For instance, I'm allergic to caffeine - even chocolate & decaf effect me, but the black tea product in the culture does not bother me.

The yeasts really need sucrose to survive well. Honey or molasses are both sucrose-based sweeteners, but because they have all kinds of other stuff in them too, you may have mixed results. I have seen that brews made with honey (by people avoiding refined sugar) tend to mold much more easily, but some folks have had luck with it.
Turbinado, rapadura, etc. are all less-refined forms of sucrose that will work well.
Alternative sweeteners such as agave or brown rice syrup have other types of sugars that aren't as available to the yeasts for their food. Stevia won't work at all.

I have had good results with a half and half mixture of white sugar and sucanat (very brown, unrefined sugar). I am told by authorities I trust that using honey is a bad idea because it contains other bacteria and yeasts that may interfere with the growth of the kombucha culture. I haven't heard anything about agave nectar.

ive been using sugar in the raw successfully....like i saw below, the culture uses the sugar for food, so there is little to none left when its done, depending on how long you let it sit.

Currently I'm using organic, evaporated cane sugar from whole foods, $0.89/lb, but I often mix it up with other types.

Turbinado, look closely as not all are incarnations are unrefined.

Sucanat imparts a very nice flavor, similar to background flavors of ginger ale.

Piloncillo works very well too and is very tasty.

Piloncillo is pure natural cane sugar concentrated by boiling. There are no additives. In addition to being a food source as rich as honey. Piloncillo has been discovered to have some unique medicinal properties. It has the reputation of being a medicinal sugar and is prescribed for use in the Ayurvedic system of medicine. Ancient Medical scriptures dating back to 2500 years state how piloncillo [also known as Jaggery in the Ayurvedic] purifies the blood, prevents rheumatic afflictions and disorders of bile and possesses nutritive properties.

I've used Agave with total success... it's just so darned expensive!

OF COURSE!

I don't eat refined sugar at all anymore.

I started my Kombucha with maple syrup and black assam tea and it's doing fine. It's never had any refined sugar involved in the process.

I didn't use honey since it's an antimicrobial I thought it might inhibit the colony, but I'll probably try it at some point when I have babies.

Piloncillo only?
Has anybody tried brewing with piloncillo as the only type of sugar?
Thanks!
Laura

Brown, raw and turbanado (sp?) sugars are all pretty much the same, they just take them out at different stages of refinery. Sucanat and Rapadura sugar are just dehydrated can juice, that is what I've been using with my baby for a while now and my baby LOVES is, growing faster! If you get the organic kind then you've got a little bit more chance of not picking up evil sugar company vibes. It's more expensive but its the only thing I use sugar for so I don't buy that much.