Nope, can't just switch the bulbs. The ballasts that run the bulbs are set at a certain wattage output, so a 150 watt ballast will not run a 250 watt bulb properly.
To build the lighting system yourself, you can just buy seperate ballasts for the MH and PC bulbs, wires, the bulbs, sockets for the bulbs, reflector, fans, and housing. Then just wire it up, bend the reflector, screw everything in, mangle & tangle it as best you can and make it work. :joy:
I, and I'm sure other people also, have some experience with a DIY lighting project, so we can help you out with that too.
You'll need ballasts for the 2 HQI metal halides and the 2 power compact bulbs.
Wires to connect everything.
Sockets for 2 HQI MH and 2 PC bulbs.
The housing and reflector.
And probably 2-3 fans.
If you do not have any experience at all with electrical projects or soldering it may be more worth it to just buy the complete ready built system all together. After all, this isn't just a few bucks this project will cost!
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)