Thank you. If you use an UV flashlight it should be 365nm and have a "black" filter to eliminate all other light. Here is what I used on the UVIVF ground foliage image. www.amazon.com/Alonefire-Flashlight-Rechargeable-Ultraviolet-Blacklight/dp/B08B638TZM/ref=sr_1_2?crid=3EJFI1URV1HN&keywords=Alonefire+brand+SV13&qid=1661559244&sprefix=alonefire+brand+sv13+%2Caps%2C237&sr=8-2
WARNING: you must wear UV blocking goggles for safety. Looks like some are included with the light. It is also recommended that your wear long sleeve heavy COTTON shirt for protection.
UVIVF works by illuminating subject with pure UV light. The subject reacts by emiting visible light. This is why a standard camera is used. The Tiffen haze 2E filter keeps the bright UV from overpowering the weaker fluorescence. Unfortunately the Tiffen is discontinued. I finally found 77mm size at B&H Photo. They call it an UV 2E filter on their site. With shipping it is about $100. Don't confuse this with a standard UV filter - it cuts out much more UV. My first filter was a Tiffen haze 2A filter. It works all most as well - see ground foliage image. You might get away with no lens filter to start. Especially with the UV flashlight.
Give it a try!
Thanks,
barondla