18/6 is good for clones, whats your growing space.
that light, look at the sticker on the top of it or the specs sheet it came with, it should give the power consumption on it, that will tell you how many watts are being used by the light, the sellers of these lights are crafty, they claim 600 watts, but the actual power consumption is much less.
people are getting pulled in with these 50.000 watt lights, when thats the total lumin output not power used.
with the banana and water cuttings, try half n half just in case the water works quicker.
years ago, my girlfriend at the time taught me a lesson with plane water, i had a northan lights plant and was trying all these methods of taking cuttings and with not much sucsess,
she came and cut a bunch of growing tips and just put them in a glass of water and stuck them on a window sill with no direct sunlight on it and they all took.
but i love new methods of taking cuttings and came across the banana method. the alo vera works well too, but the leaves need to be big n thick for it to work. luckaly im a wizz at growing alo vera and have about 500 of them, so no shortage of them around when i need them.