what happens when the HPS bulb has out lived its gro life??

I have had to use an old (18months) 400w bulb on my flowering plants (2) until I can get a replacement.(broke the last 1)... Does anyone know how this will affect the bud's..? they are about 6wks into flower and there is a homemade LED light(with loads of reds) hanging above each 1

is this a dumb question..? its just that I've been told that the hps bulbs only retain their efficiency for a certain number of hours...does any one know what/how long this is..??

you should buy a new one as soon as you can!!! you can use this one temporarily but change it asap!!!