Hi, I have two ballasts that need bulbs, and need some advice. A 1000W MH ballast that is maybe 25 years old and a 1000W switchable(MH<>HPS) that is much newer. I have been told bulbs come in "pulse" and "probe" - so I am not sure what replacement bulbs would work in these ballasts - any advice appreciated! PS can take photos of the ballasts if necessary