When to switch to HID lights

DragonPhoenix

DragonPhoenix

Well-Known Member
I'm starting a new grow and currently have seedlings under CFLs. I'm wondering at what point I should make the switch over to my MH lights. When they have 3 or 4 sets of leaves?
 
you can use the mh now but for better results go for an hps.you can use this lamp from seed to flowering without any changing.just go from cfls to hps when the seedling is about 2" tall just keep it well away from from the lamp dependent on lamp wattage.
 
Thanks for the response. I've got 2 400w MH lights for veg and then I plan to switch to my 1000W HPS for bloom after vegging for about 4 weeks.
 
LUDACRIS said:
you can use the mh now but for better results go for an hps.you can use this lamp from seed to flowering without any changing.just go from cfls to hps when the seedling is about 2" tall just keep it well away from from the lamp dependent on lamp wattage.
Click to expand...
Ideally you want MH and HPS bulbs. HPS is fine from seed to harvest, but MH will give plants a better quality of light during veg phase. Switch to HPS when you start 12/12 because the same is true for HPS vs. MH during bloom phase.

To answer the threadstarter's question, you can switch from CFL's to MH as soon as they sprout, just keep them a good 3-4 feet away until they're strong. Or you could keep them under CFL's for the first 2-3 weeks if you're concerned about electicity or heat from the HID.
 
I think I'm more concerned about the inefficiency of running a 400w MH light if my plants are so small. I'm just wondering how much of a benefit it will be over the CFLs and at what point would be a good time to switch over to use all of the lumens that the MH light puts out. Obviously if I had a ton of sprouts or clones I'd throw them under the MH light right away. However right now I just started 6 from seed so there aren't a ton of plants to put under the light.
 
Wait until they're well-rooted, usually 2-3 weeks from sprout. Then switch to MH for more agressive veg growth.
 
Cr8z13 said:
Ideally you want MH and HPS bulbs. HPS is fine from seed to harvest, but MH will give plants a better quality of light during veg phase. Switch to HPS when you start 12/12 because the same is true for HPS vs. MH during bloom phase.

To answer the threadstarter's question, you can switch from CFL's to MH as soon as they sprout, just keep them a good 3-4 feet away until they're strong. Or you could keep them under CFL's for the first 2-3 weeks if you're concerned about electicity or heat from the HID.
Click to expand...
I recently found a ballast on CraigsList that claims to be able to run both MH and HPS. I'm gonna be limited to 400W total, as I can't do something that will seriously impact our power consumption.
2 New Sun Systems VI 1000 watt switchable Hydroponic Ballasts

I'm only just beginning to learn about the lighting and photosynthetic requirements of mj, though I'm somewhat familiar with the lighting requirements of aquatic photosynthetic organisms.
 
That ballast looks decent, though I have no direct experience with that brand. I'm pretty sure you'll need to buy seperate lamps for a switchable ballast. I have a HPS ballast, but I'm able to use a MH conversion bulb. All I have to do is switch bulbs.
 
You're limited to 400w but looking at two 1000 watt ballasts? You can't run 400w bulbs in 1000w ballasts, you know that right?
 
OregonMeds said:
You're limited to 400w but looking at two 1000 watt ballasts? You can't run 400w bulbs in 1000w ballasts, you know that right?
Click to expand...
I have never heard that.

I have run mh bulbs with hps ballast the same wattage. No problems did it with a few grows.
 
OregonMeds said:
You're limited to 400w but looking at two 1000 watt ballasts? You can't run 400w bulbs in 1000w ballasts, you know that right?
Click to expand...

Perhaps I was not clear. I have a veg room and a bloom room. The veg room has two 400w MH lights. The bloom room has one 1000w HPS light.
 
That kind of answers my question, because it seems that it's good to use both lights, rather than one. The reason why I put up that link is because I've only used MH, and that was a long time ago. Can you just switch the bulbs when you want to swap 'em out? Or do you need a separate unit for each type of bulb?
 
Seamaiden said:
I recently found a ballast on CraigsList that claims to be able to run both MH and HPS. I'm gonna be limited to 400W total, as I can't do something that will seriously impact our power consumption.
2 New Sun Systems VI 1000 watt switchable Hydroponic Ballasts

I'm only just beginning to learn about the lighting and photosynthetic requirements of mj, though I'm somewhat familiar with the lighting requirements of aquatic photosynthetic organisms.
Click to expand...


I have a system that runs 400w MH and HPS, it has a switch to turn to either one...and has 110 or 220 capabilities as well.
 
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