Yeah,five star says it breaks down into yeast neutrient. I don't know how long that takes. I don't believe they mentioned that part. But such a smal amount from an airlock,even a blow off tube,shouldn't matter. For example,I use 1/2 gallon vodka jugs for blow off rigs 1/3 full of water with a splash of starsan solution. The solution being .75oz of starsan per gallon of water,with a small splash in 1/3 of a half gallon being about a pint of water,the amount of the TTL volume that's starsan is pretty miniscule. Enough to do the job,but not enough to be harmful to us.
Everything works if ya let it-Roady(meatloaf)