600W SE was and still is on my plans.
Right now i'm dealing with peak temps of 82-86F with the 400W HPS. My AC unit is a portable one and not very potent, so i was afraid of not being able to deal with the higher temps of a 600W bulb. Here is summer right now, but it only has a month and a half left, so maybe those temp won't be a problem in autumn and winter.
The 600W bulb and ballast would cost me 90$.
About CMH:
Main options here are made by a national company that uses General Electric bulbs and make their own mechanical ballasts. The 300W fixture is in fact a 2x150W. I add some pics here, they are not very good looking
They cost like 225$
Another option i was thinking about is to boost the 400W HPS with a 180W led panel with Citizen COBs. But since QB is the new trend in leds, i'm not sure about the COBs. I believe this setup would be more heat friendly that the 600W, but can't tell for sure.
It costs 180$
I believe it would be a choice between the 600W or the 180W COB to boost the 400W HPS.
I could use the 180W led also as my veg light in the future and not spend so much vegging with the 400W HPS. But that led panel costs as two 600W bulbs and ballasts. In the other hand, a 600W replacement is about 30-40 dollars, so in the future they would add up to the price.
What do you think about the 400W plus the 180W led?
When you say 82-86F, do you mean ambient or inside your tent? Only reason I'd grow in temps over 80F is if I was using CO2, and my RH was over 50%.
Controlling your grow rooms environment is priority #1 here. I'd suggest investing in better environmental control over lights if those are the temps in your tent. Spend the money of your budget on better cooling (and in some rare cases, heating. Whatever you need to control temps). I'm not sure if you have humidity control, proper airflow, or proper ventilation; but if you don't then fix those issues before getting a new light.
In terms of what is most important for a good grow, it'd be something like this;
Environment control (temps, humidity, airflow, and ventilation) > quality of soil > quality of plant genetics/strain selection, > light would be last.
A room with mediocre genetics, Miracle-Gro soil, a single 180w LED light (like the one you mentioned) will shit on a room with high temps/low humidity/no airflow that houses the best soil and genetics in the world underneath the best grow lights.
A room with bad environmental control will fail; even if it has the best lights, the best strain in the world, and the best soil.
It's easy to be tempted to go cheap on certain things when you're on a budget and trying to grow your own, but don't. Trust me, I learned that the hard way. And I know I'm not the only one.
Control your environment first. This means you can keep the room between 73-78F at command, can keep RH in the 40%+ region, have enough airflow that every single sqft of your canopy gets a nice and gentle breeze from an oscillating fan's coverage(s), and that you're exchanging the air in your grow room to sufficiently replenish fresh CO2 into your room.
Once one has done all of the above, they can then focus on the overall quality of the soil.
Once the environment and soil are up to snuff, now its worth improving your genetics.
Then, finally, once all of the above has been satisfied, then one can finally start looking into improving their light source.
Thanks for the clarification on the lights, by the way. Now I know that anything but LED and SE are out of the question.
The 400w + 180w LED could be worth while for a few reasons. I'm sure you've done your research on quality LEDs (I know little), but ensure you're getting a quality LED fixture capable of quality results. Assuming that:
The only "con" to adding the 180w LED is that the part of the canopy under the 180w LED would show better growth, bud structure, and terpene production as opposed to the part of the canopy under the 400w SE. Not really that much of a "con", just be kind of a tease to have 1/3 of your canopy be superior to the other 2/3 lol
You could even mitigate the above "con" by re-arranging the plants a few times a day. Sounds silly, but its why light movers work so well.
Consider outdoors, the sun is never directly overhead the plants for the duration of the daylight cycle. Outdoor plants get anywhere between 3-5 hours of direct overhead sunlight, with the rest of the light not being overhead. Moving the plants in this set up is definitely not mandatory, just a little extra step that would ensure all of your plants get time underneath the LED.
The LED would also be good for your situation because it doesn't produce as much heat, as you pointed out. Then, in the future when you're able to budget for more lights you can simple grab another one or two of those 180w LED lights and your entire tent will be filled with LEDs.
Definitely focus your environment first and foremost though.