Wattage question

[JerryMawuana]

My grow space is 2x4x5.5 feet with a 600 watt dimmable ballast. I have it turned down to 400 watts and am 1 week into budding. Would it be beneficial to turn my light up to 600 watts for budding? I'm not concerned about the cost/yield ratio. I'm more just wondering if my girls will be ok with that wattage in that size of tent?

[D.A.A.S.69]

JerryMawuana ,if you are able to handle the extra heat, from the 600watt, then I would most definitely use the 600watt, it will help your buds alot.

[JerryMawuana]

I'm awesome thank you. I can handle the extra heat no problem.

[Toker1]

It won’t help the buds if he is already maxed out on room to raise the lights up. You can bleach the tops this way.

[Toker1]

Besides wasted light, high temps, and or low humidity issues... if you increase your light output, you will have to raise your lights higher to avoid bleaching the tops. Do you have the head room for that?

[Mr.furley]

JerryMawuana it is time to learn supercropping you can do it up to harvest if you need.
I run a 600w hps at 14inch in a 6' tent with no light bleaching.

https://www.growweedeasy.com/how-to-super-crop-marijuana

[JerryMawuana]

I've been reading up on super cropping. I'm definitely going to give it a try, On my next crop probably. This crop is to learn the plants. Last night 4 out of 5 showed me their gender, 2 girls 2 boys so fingers crossed that last one is a girl.

[Mr.furley]

Fingers crossed.

[kingfish]

Can't ever have enough light.

[JerryMawuana]

My plants are around 2 feet tall right now (So still able to grow up to 8 inches). I'm just letting them grow naturally since I'm still a rookie. Exhaust isn't an issue, my exhaust fan moves 436 feet/minute. It's hooked up directly to my light hood, the other side has my carbon filter directly hooked up with a 6 to 4 inch reducer. Plus ample air movement and more if needed.

[Toker1]

I have done a 600w HPS in a 4x2x5 before. The farthest corners were hard to light up well as my cool tube hood only fit in one direction back then. So I ended up dimming the HPS to 400 and using 200 worth of compact florescent in the corners. The better light spread action really helped those far corners.

[DrPhoton]

600 watts for a 2x4 is too much for that size. Ideally you want the average photon density to be between 500-700umols with no more than 1000umols max. 600 watts in a 4x2 outputs around 1300umol of photon density. Which is far too much for plants to tolerate. You can get away with over powered light sources by raising them enough to prevent such problems, but this is wasting light through reflective losses and you are probably better off dimming the fixture rather than just wasting that extra energy on heat. Unless of course that heat is beneficial to you, which in that case its no problem.

Dimming to 400 watts will provide around 850umols of photon density which is just in the region of acceptable levels. 300 watts will be around 650umols photon density which is about the same that a 600w provides for a 4x4 space.

You should not dim your sodium discharge bulbs more than 50% as the photon efficiency starts degrading significantly. You should also ideally never dim your metal halide as they start degrading almost straight away with any sort of dimming levels. They also change their spectrum balance with the blue part of its spectrum loosing much of its energy. If absolutely nessecary, you can dim the MH down to 75% max. You will suffer in efficiency losses but still maintain the majority of the spectrum.

[Toker1]

I assume these photon density specs are captured for single ended bulbs and are only increased in the case of double ended bulbs.

[DrPhoton]

Correct. These calculations are based on single ended technology using data from highly accurate integrating sphere measurements. Which takes into account the reflective losses from the light fixture. The photon density calculations are true averaged values calculated from these photon flux data, which is entirely different from single PAR measurememts which do not actually measure in per square meter with artificial light sources. They are merely inflated spot measurements that references only the diameter of the sensor.