HPS to MH fixtures?

hey fellow nature lovers, i'm using a 600W HPS light and fixture but I've read u can place a MH bulb of equal wattage in the fixture without any adverse effects? does anyone know if you can do this or has attempted it? i'm asking cause I'm short of the $$ at the moment but wanted to do MH through the veg stage and HPS through the flowering stage. cheers

no, u can't do that man, don't do it!!! u can buy a 600 watt MH CONVERSION bulb and put it in, but not an ordinary one, that would be a big mistake

BOOOOOOOOM!!! goes the ordinary bulb LOL

thanks mate! do conversion bulbs cost more or would i be better off just getting a 400W MH and ballast etc for the veg stage and then use the 600W HPS to flower?

As far as I understand the ballast itself has to be a conversion type. I could be wrong tho'. I've had 2 lamps that you could put both MH and HPS bulbs into but I had to flip a switch on the ballast...also the conversion lamps were pieces of shit.