Keying a transparent object for green screen is hardly the easiest thing to do.

I can only suggest the following - but I'm just thinking out loud here, this is not from experience of your particular problem ok?

You can maybe try multiple passes of greenscreen keying of your footage. use different settings to pick each each 'level' of green through the water. Eventually you'll get it. Also, and this might well depend on exactly you want to put behind the water, you could just mask the bowl off and apply some colour correction filters to get what you want.

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