Hps light 250 watt or 400 watt?

Tent is 90.90.180, which hps lamp is best for two/three plants, a 250 or 400 watt?
I think 250 watt is enough but they gave me advice to buy 400 watt. Or is this just a way of selling of more expensive things?
Thanx for anwering,

I believe that you can never have too much light; As long as you can control the temperatures to within an acceptable range.

Now that you know what the store want to sell you; shop around online. I get great deals by looking at what all is available on ebay. That will give you a good read on wheter you are spending too much, locally. Hope this helps.

Thanx for answering, of course this helps. I thought there were limits about size of a tent and the watt of the light. And now I’m looking for more watt of the lamp on Ebay! Shopping around… :stuck_out_tongue:

Actually there is such a thing as too much light:

Sorry; You can keep Wikipedia. Not fact, consensus. Never read info at that site. Thanks anyway. Peace :slight_smile:

Are u f’n kidding me. It’s not just wikipedia! It’s botanical science. Anyone that knows even the slightest thing about actual science and botany knows this stuff Latewood. I thought you had actual professional experience. SMH.

Any number of colleges and their botanical scientists will have to disagree with you Latewood…
My point was; A 400 watt lamp in that space could not be too much light! Sometimes, You give way too much information, and confude the issue; as mentioned by the member. I have seen extreme overkill with indoor lighting, and no ill effects. The only tiime I would advise worrying about light intensity would be under the Sun! Please do not call me out again MacG.

When you make broad statements discounting wikipedia that are actually inaccurate I wll call you out Latewood.

Well, no problem. Wikipedia or not I am still alive. I didn t understand it anyway lol :roll: :lol:

Basically what it means is there could be detrimental levels of lumens/FLUX/PAR and the chlorophyll can break down and stop working. You will notice potentially two things if you have too much light, one not unlike having too strong of light too early the plant will literally start to pull or shrink away from the light, even if you are controlling the heat, the other thing that will happen is the color will bleach right out of the plant as the chlorophyll is damaged and is not able to be repaired or replaced at the high energy levels the light is producing.

There are ways to potentially increase the ability of the plant and it’s chlorophyll to process more energy, adding CO2 and more nutrients – i.e hydroponics that can increase the nutrient supply and water and the speed of which the plant can deliver these things through the roots to the stems and leaves is one way, however even then this can only increase the total amount of light a plant can take by a small margin more, some things just won’t be able to move fast enough, creating and processing enzymes fast enough and even nutrient and water transportation and the transpiration can only move so fast and the plant will quickly hit that limit and then the plant will start to bleach out.

Because of the way light intensity drops off so quickly with a little distance, the inverse-square law, you will see this when a plant has part of it get too close to a high intensity light in a cooled hood or a High Power LED. You can put a whole lot of lights in a small room and as long as you have some distance from the plant you are going to have a hard time really getting to that intensity because of the inverse-square law. You usually will only see these problems in really really small grow rooms with really really high powered lights that do not contribute a lot of heat, this more easily occurs with LED lights as they produce so little heat.

I guess you won’t see it happen much in a large agricultural grow where the high powered lights might be yards or meters away from the plants at the closest, that crazy inverse-square law again, maybe this is why Latewood is not as familiar with this as a problem and he doesn’t really do LEDs.

I really don’t think the question was answered.

Which is better 250 or 400 watt? Does it depend on your grow space??

I plan on growing femenized autoflower, is a 250 w HPS sufficient?

It would mostly depend on your grow space. I don’t know about the efficiency of 250 watt vs. 400 watt HID lights and I don’t personally use HPS or MH. I do know that a 600 watt HPS is much more efficient than a 1000 watt HPS, in other words the 600 watt HPS has more Lumens/LUX per watt that the 1000, per watt, the 1000 watt will still have more lumens overall, so ten 600 watt HPS would produce more lumens than six 1000 watt HPS. Also HPS produces more lumens than MH per watt, so say a 400 watt MH would not put out the total LUX as a 400 watt HPS.

Up to a point you can put as much light as you can and still deal with getting rid of the heat. You do have to be aware of photo-inhibition as stated above.

In general minimum amount of lighting needed is around 2000 lumens per square foot.

Optimal is around 5000 lumens to 7000-10,000 or maybe even more, lumens per square foot.

No matter the type of light, if you can find the exact specs for its lumens/FLUX per square foot (or the equivalent PAR for red/blue only LEDs) you can use this as a loose guide as to what you need as minimums:

Seedlings and clones require about 400-1000 lumens per square foot.

Vegetative growth requires about a minimum of 2,000 to 3,000 lumens per square foot.

Flowering requires about 5,000 to 10,000 lumens per square foot, ideally, and can take possibly much more.

10,000 lumens is supposed to be about the average power of the sun at sea level on a clear day at high noon, or something like that, lol.

8,000 - 12,000 lumens is supposed to be about the power of the full sun without any overcast or no clouds.

It’s not ideal, but you can make do with 2,000 lumens for an entire grow if necessary.

Yo0ur question was answered! Get a 400w

Well, mostly, yes 400 watt would provide more or better light than a 250 watt, but what is better for your size of space might be different if it is a very small space.

What do you use then??

Thanx for all the information.
I bought a Pioneer Pro 450W Medical Flower Plants LED Grow Light Panel Plants Grow&Flower on Ebay. Because of the low costs in electricity and less heat than a Hps light in the small tent.
And I’m very positive about this Led grow light. The temperature is between 25-27 C. I keep the humidity around 70-80% for veget. I bought the seeds just for fun when I was in Amsterdam; Greenhouseseeds, ex. Cheese. I started in June and three plants are still in vegetation. I had some problems with spin. Now they are stronger than before and now using Led , they are just doing fine. So maybe in two or three weeks they are going in the flowering period. I tried some FIMing on the plants, so I wait some weeks. This is my first try and I have to find out a lot of all these plants/technics. And I find it very interesting and we can learn so much of each other at this forum.

Is anyone else using Pioneer Pro 450W Led’s.

I was reading up on it last night but I would rather hear from someone else who uses them and has harvested.

I do use LEDs, I am not familiar with Pioneer Pro LEDs though.

Well now; If you want to go LED…MacGyver_Stoner is the Guru.

Sorry if we got a bit off track in this thread. I have multitudes of HID lamps, CFL’s, and Fluoros. The last lamp system I bought was the IPower 400watt, MH/HPS digital ballast. I love it and for the begiiner or expert grower, it does the job. About 120 bucks.

whatever you decide, we will be here to support you throughout you grow. Peace.lw

Sorry if I have gone off topic, if you like I will start another one.

MacGyver, which lights do you use. I have auto flower feminized seeds and am only new to indoor growing.

My grow space is really small, 0.5 m x 0.9 m x 1.7 m and I would have real troubles with heat dissipation, also the climate here is starting to warm up as it’s coming into the tropical wet season.


Which LED lights do you use??

I do not endorse any name brand, the most credible and reliable name brand LED systems are way over priced right now in my opinion.

The system I started with is not in business anymore and I modified it so much that is now my own custom rig and I do not build them for sale or otherwise, although one could be built from scratch at a fraction of the price of any name brand and maybe even a fraction of the knock off direct from China equivalent models. A good LED system can and will give you amazing results and the best bang for electric bill buck.

LED lights right now have no real good “industry standard”, especially as to how they are marketed and sold. Some companies will give you an accurate “HID wattage” equivalent, but most do not, even some of the really good manufacturers, all they give you is the “theoretical” maximum wattage. For example, if the light is made of 100x3 watt LEDs, then it would be marketed as a 300 watt LED fixture. But it is likely really only running at about 150 watts and it may or it might not even be driven at half power and maybe less than a third, say only 75 watts and may not be putting out the equivalent of a 250 – 300 watt HID light. You are going to have to do a lot of research and some of these answers may not be available, even from some of the more reputable manufacturers.

In general you want to be sure both red, and both blue spectra are covered and a little IR and a little UV.

UV 410 nm and Blues 430nm~440nm and 450nm~460nm, and Reds 620nm~630nm and
645nm~660nm, and IR 850nm

Only about 25% blue is needed for tight internodes and to avoid stretching. Very very little IR and UV is needed at only about 2% each.

And a lot of full spectrum white LEDs are often added, I have added a lot to my own setup mostly just because it makes the light easier on the human eyes, more than performance, full spectrum white light will be rated with the kelvin temperature rating and 2700 Ks are redish “warm white” and 5000-6000 Ks are about perfect/pure/true white and much above 6000, say 6500 K is blue heavy white, often called cool white. More heavy on the blue light for veg and more heavy on red for flower. Most lights will be marketed for veg or bloom or some may be called full spectrum for dual purpose veg and bloom and you will notice the ratio of red vs. blue change for the said light.

These are the loose guides to evaluate the technology, most of the well established name brands follow most of these as guide lines and even among the better companies the exact balance and ratios are not always agreed upon. But if you do some research you can probably find an Apollo or Blue Dog equivalent light for half the price, it even likely comes out of the same assembly line but without the name brand stamped on it. P.S. I only mention these two brands as they are well established, not that they are necessarily any better than some of the other new reliable name brands. California Light Works and Bloom Boss are two other well respected name brands but you will notice all of these tend to be a bit on the pricey side, Apollo might be the most affordable. I personally have no experience with these brands but they do seem to get the highest ratings and recommendations around the web.

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