hello all, i have 2 x 600w HPS ballasts. can i put a 600w MH bulb in ? is there a special bulb i could use in the hps for veg ? thanks Middy
your ballast serves as a starter. if you notice the hps starts up fast yet the mh requires more time. the bulbs would not be compatible unless the ballast was switchable. even then the bulbs are a more expensive bulb because there are nobody making the 600mh bulbs, only the conversion bulb will do. go get the mh ballast. folks are moving away from them so fast that they are cheap now. you can find them used for 50-60 bucks
also check out the hps start to finish thread. we really dont need mh as cfls or t-5s have taken the cost down and the plants do well on hps as long as they are conditioned if seedlings or clones. so unless your set on the mh idea then id do cfl veg and hps flower and give the mh bulbs to the next person. a couple of safeway 42w=200 incandescent. this is a bunch of light for veg and at 10 bucks each you reall cant go wrong, hell even the ballast is included as the bulb configuration. even a couple half spent cfls are good enough for veg. i think this is what id do if i were you. its cheap and makes good sense
i understand what you are saying but i want 2 x 600w MH, i have used 2x 600w hps start to finish for the last 3 grows with a light rail 90 plants first then 100 and this time 65. i have never used MH bulbs before and i want to give them a go. i use cfl's and tubes in two clone areas now but cfl's for a 10/18 site R-DWC scrog setup would be a pain in the arse hence the 600mh question thanks for your input & also i'm in Czech not the USA. Middy
The actual ballast is identical for HPS and MH, but HPS requires an igniter, and when you have a "HPS ballast" you actually have a ballast and an igniter enclosed in the same housing. The igniter could damage a regular MH bulb. A MH conversion bulb is made to absorb the igniter pulse from a HPS ballast. A switchable HPS ballast lets you switch off the igniter so that you can run a regular MH bulb off it. A digital ballast should be able to run both types of bulbs, no "conversion" bulb or switch needed.
I have done grows with and without a MH from start to finish. I noticed that with a MH bulb in the veg stage the plants grow just a bit greener and bushier and in the harvests their is not that much of a difference in harvest weight. In the old days their was no switchable ballasts and the cost was too great to having both. With the new digital ballasts that are switchable to MH and HPS many are now useing MH bulbs Alot of digitals are even dimmable where you can put in a 1000 watt bulb and knock the power back to 600 watts or you can even use a 600 watt bulb Just my observation