<a href=showthread.php?s=&postid=9341176#post9341176 target=_blank>Originally posted</a> by dippin61
no reason to really. i just ran the numbers this weekend on sanjays site, because i was thinking about going with the xm 20k on HQI ballasts.
your only gaining about 6 ppfd, and losing a spike in the 460nm range compared to the mag ballast driven ones.
XM 20k on mag ballast is 73 ppfd
XM 20k on HQI ballast is 79 ppfd
not worth the extra money in ballasts, and more often bulb replacement