I feel this would be a very interesting experiment and what an interesting job it seems you have. I would try it although perhaps you could do two groups, one with the regular, fresh guano (which is probably the best for the begonias) and one area where you use the diluted solution. Just don't go overboard, try like one or two pieces of poop if you are going to try to give it straight to the plants.

 

I put bat guano around the base of one of my orchids thats likes extra nitrogen. Do you have frogs in your tanks, if not the plants could definitely use some nutes! I also have made a tea and watered my orchid and some other heavy feeders. Haven't seen any negatives yet! Have no clue what fresh stuff would do... i think it be extra strong, maybe dilute it more.

 

not yet any frogs - good to know, thanks!

 

Bat Guano is excellent fertiliser and the fresher the better. I wouldn't hesitate to use a dilute bat guano tea on vivarium plants but I'm not sure how it might affect your frogs.
There's going to be really significant quantities of microbes that you might not want to force into contact with your frogs skin in any guano tea you make so I would start with fairly targeted feedings rather than spraying the whole tank despite dilute compost/guano teas like this also being good foliar fertiliser.
I used to use bat guano quite a lot growing some organic plants and always got great results.

 

just saw you actually mention not having frogs in the tank so nothing to worry about. 1 tablespoon of guano in a litre of warm dechlorinated water is a good starting point.

 

thanks! which species guano do you use most of the time?