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.