MH & HPS question...

[Coolthanksbye]

I'm currently in my first grow and everything has been going great. I've been using a 400W MH for 18/6. I just switched over to 12/12 and changed the bulb to a 400W HPS. The issue is the HPS doesn't seem to be working right; the middle glows a faint purple when plugged in and that's it. The MH bulb works fine in the same fixture. The MH and HPS bulbs are 38K lumens and 55K lumens, respectively. Would I be greatly decreasing my yield by sticking only with the lower-lumen MH for the flowering stage, or do I need to exchange my HPS and change to that as soon as possible? Any input is appreciated!

 

[bigfanofpj]

Can you use the same ballast for both types of bulbs? I"m not sure.

Then why did I post...hmmm I dunno. Just wanted to see myself think

Rock on!

 

[Coolthanksbye]

Can you use the same ballast for both types of bulbs? I"m not sure.

It's one of those fixtures that came with both interchangeable bulbs. The HPS is receiving power, but it's only slightly glowing.

 

[RangerDanger]

If your POSITIVE the system you have will run both MH & HPS, then it sounds like you need a new HPS bulb.
HID bulbs wear out, just like all light bulbs, and should be replaced every year.
Save yourself the hassle of having 2 bulbs and buy an EYE or other full-spectrum bulb.

 

[Coolthanksbye]

Thanks for the help Ranger- always givin good info. Never heard of an EYE, but I'll definitely look into it for my next grow. Do you think I can complete the current grow (just started 12/12 yesterday) with the MH?

 

[MadameCrash]

Yes! MH is actually closer the sun's natural light spectrum than a standard HPS bulb.. MH also contains the UVB spectrum that HPS doesn't. The plants may not stretch as much, and they will probably have a higher leaf to calyx ratio, but the buds will be more dense and crystally... The only thing to note - you have to keep a MH closer to the plants than the HPS during flower to get nice results..

Just my experience anyway....

Peace
MC

 

[RangerDanger]

The reason people use HPS for flowering is because MJ flowers in the fall.
Spectrum-wise, MH more closely replicates the summer sun, HPS more closely resembles the fall sun.
You can get a good yield with MH, but imo HPS is best for flowering.

 

[RooRman]

I agree with Ranger about the MH and HPS. I have found the same thing to be true.

As for your light, make double sure it is a switchable ballast, i.e. one that will accept a MH bulb and an HPS bulb. These systems may require some down time before you switch from MH to HPS. I have read it is a good idea to turn the ballast off for a while before switching from MH to HPS. In addition, make sure all your wiring is good, the wattage of your bulbs matches your ballast, and that the bulb you are attempting to use is clean and the filament is undamaged.

 

[Racefan]

When you run a MH in a HPS system you have a toggle switch that bypasses the starter since MH doesn't require a external starter. If there is not a switch that changes from a MH to a HPS then it is not a ballast that runs both bulbs. If the metal halide ran in the system then all wiring up to the starter is fine and it's either the switch itself (if there is one), the starter for the HPS is dead/dieing or your system isn't switchable like you think it is or your HPS bulb is dead/dieing.