I'd stick with plain water for seedlings. Some growers use a vitamin solution, but you really don't have to, and the risk of messing with newly-popped beaners is not one you want to take unless you do a test run on shwagseed (bring them to 5 nodes at good health and that will tell you if it is okay or not- the test should take 2-3 weeks).
Those Thiamine supplements might have something else in them too- SuperThrive has a lot of Urea and is very 'hot' for seedlings. You can overapply it very easily by mistake!
stinkyattic Reviewed by stinkyattic on . Vitamin B1 prior to Germination Supermax Vitamin B1. Got it for free a while back and haven't really used it for anything. I'm starting Dutch Passion Blueberry, moving away from the bagseed to hopefully yeild btter and better quality. Says to soak seeds for 15min in a solution of 3ml per Liter. Will this really help the germination? Rating: 5