Bignutes
Well-Known Member
True that, I just don’t have the means to get a par meter. Getting the DLI would be nice, after hearing that a hydro store has one to rent maybe getting the DLI is right around the corner for most homegrowers
How much light do you really need?
- Thread starter Bignutes
- Start date
-
- Tags
- light sizing square foot watts
ComputerSaysNo
Well-Known Member
An app on the phone is probably enough. You do not need 0.1% tolerance measurements (I guess).
A cheap dedicated Lux meter on Amazon costs around $20.
From there you can convert to PPFD if you know your light's color temperature. Another approximation that is probably good enough.
jimihendrix1
Well-Known Member
A Gavita 1700e is meant as a 1:1 replacement for a 1000w HID. i have used the 1000w Hortilux HPS in a 4 x 4 for almost 3 decades. A 1000w HID has been the indistry standard for a 4 x 4 since they came out in 1977-78, ad was known as the Supernova. It was a Metal Halide, and if one wants to get technical, a bulb they used in nuclear subs to grow veggies was the first commercial HID sold on the market, but it was so fragile they wouldnt guarantee it in shipping. The Supernova came out about 6 months after the navy bulb.
The Gavita 1700e is 1700umol, and 645w of Samsung/Osram diodes. The 1000w Hortilux is 1600umol. Close enough for a direct replacement.
So the Gavita 1700e is a direct replacement for an HID that is made for a 4 x 4 area.
At that rate the Gavita is 42.5w Sq/ft, and the 1000w Hortilux is 62.5w sq/ft. That is the formula I use, and will continue to use, and IMHO makes it simple. Trick is for the LED is that one has to use Samsung/Osram diodes.
While w x sq/ft may not be the end all say on the matter, its close enough.
The Gavita 1700e is 1700umol, and 645w of Samsung/Osram diodes. The 1000w Hortilux is 1600umol. Close enough for a direct replacement.
So the Gavita 1700e is a direct replacement for an HID that is made for a 4 x 4 area.
At that rate the Gavita is 42.5w Sq/ft, and the 1000w Hortilux is 62.5w sq/ft. That is the formula I use, and will continue to use, and IMHO makes it simple. Trick is for the LED is that one has to use Samsung/Osram diodes.
While w x sq/ft may not be the end all say on the matter, its close enough.
calvin.m16
Well-Known Member
@jimihendrix1 You post a lot of really false information. Apparently you saying the Gavita 1700e being a "direct replacement" counters Gavita's own words saying that the 1930e is THE ONLY direct 1:1 HPS replacement.
Gavita CT 1930e LED | Gavita – Retail
Watch how easily STIIIZY and LIIIT Farms replaced their HPS lights with energy-saving CT 1930e LEDs. Download whitepaper Benefits An average of 46% higher yield per watt vs HPS*
gavita.com
jimihendrix1
Well-Known Member
In reality straight from their site they compare the CT1930e to a DE 1000e.
And in your above Gavita ad it also stated the CT1930e has a 20% energy saving over the 1000w DE HPS Fixture.
Better learn to read, and apply reading comprehension.
Energy savings vs. 1000 W DE HPS fixtures (based on average wattage of each fixture)
The Gavita Pro 1700e LED grow light has a lower wattage than one might think, with a 645-watt power draw. This means it can replace a 1000w HP lamp with compromising light intensity and quality.
Best LED Grow Lights of 2021 Comparison & Review Test Using Laboratory Data
The Gavita Pro 1700e LED uses over 3,300 diodes while the next closest brand uses slightly over 2,200 diodes.
And in your above Gavita ad it also stated the CT1930e has a 20% energy saving over the 1000w DE HPS Fixture.
Better learn to read, and apply reading comprehension.
Energy savings vs. 1000 W DE HPS fixtures (based on average wattage of each fixture)
The Gavita Pro 1700e LED grow light has a lower wattage than one might think, with a 645-watt power draw. This means it can replace a 1000w HP lamp with compromising light intensity and quality.
Best LED Grow Lights of 2021 Comparison & Review Test Using Laboratory Data
The Gavita Pro 1700e LED uses over 3,300 diodes while the next closest brand uses slightly over 2,200 diodes.
calvin.m16
Well-Known Member
The Gavita 1700e LED still doesn't compete with a 1000w HPS. I'll pay a few hundred more bucks a month for electricity than lose a few pounds to LED. I've yet to see a LED grow that tops HPS. Weight isn't everything.
ComputerSaysNo
Well-Known Member
That's quite a bit of mumbo jumbo coming from somebody who accuses others of putting out "false information".
calvin.m16
Well-Known Member
You mad?
ComputerSaysNo
Well-Known Member
I no longer get mad at people for shit-posting. It just happens way too often here.
If You Can’t Measure It, You Can’t Improve or Manage It.
In most cases, this is true, but theory and calculations are also needed. Because simply applying a sensor is not always enough.
The inverse square law works at 100% of a point light source in free space. In optical fiber by 0%. In real boxing, somewhere between them and at different points in different ways.
Let's say you have a growbox 2 * 2 * 6 feet with a Led bar on the entire roof 2 * 2, and its machines and bottom have a reflection of 90%.
If you place the probe 1 foot away from the lamp, it will read eg 1000 micromoles. there is no inverse square law here (unlike point HPS), because the light from neighboring chips is added to the light of an individual chip decreasing according to this law when the sensor decreases. However, it still does not work very well due to the reflection of the walls. There is also no "optical fiber effect" yet, because at this height the reflection from the walls is insignificant. While everything is simple.
Now place the sensor 5 feet from the lamp (1 foot from the bottom). It will probably read about 200. Here the "Fiber Effect" is already starting to work, but then why is the sensor reading so small? When light is reflected from the walls twice, it will remain (0.9 * 0.9 = 0.81), three times 0.73, four times 0.66, and so on. Probably three times is the maximum that happens in the stead, but not sixteen to weaken to 0.2.
This is where the difference between the reflection in the box and the fiber is manifested, and the fact that the loss in the fiber is much less than 0.9 is not the main thing (the number of reflections in the box is not so large). The walls of the box, when reflected, also strongly scatter the light, that is, give it all sorts of directions.
What does the sensor measure? - light falling on it at an angle of 90 radii and light from 0 to 90 multiplied by the cosine of the angle (from 0 to 1). That is, not the whole value, such as a microphone (although most also depend on the direction) or a thermometer. And a small part of the light even comes from below reflected from the bottom.
It's just that the sensor does not catch all the light, as well as the human eye and the camera, and therefore it "works" ideally in these tasks.
Plants catch light in all directions inaccessible to the measurement of the sensor and this should be taken into account. For a complete picture, it is worth at least placing the sensor in the usual horizontal, vertical and inverted position to summarize the readings.
In most cases, this is true, but theory and calculations are also needed. Because simply applying a sensor is not always enough.
The inverse square law works at 100% of a point light source in free space. In optical fiber by 0%. In real boxing, somewhere between them and at different points in different ways.
Let's say you have a growbox 2 * 2 * 6 feet with a Led bar on the entire roof 2 * 2, and its machines and bottom have a reflection of 90%.
If you place the probe 1 foot away from the lamp, it will read eg 1000 micromoles. there is no inverse square law here (unlike point HPS), because the light from neighboring chips is added to the light of an individual chip decreasing according to this law when the sensor decreases. However, it still does not work very well due to the reflection of the walls. There is also no "optical fiber effect" yet, because at this height the reflection from the walls is insignificant. While everything is simple.
Now place the sensor 5 feet from the lamp (1 foot from the bottom). It will probably read about 200. Here the "Fiber Effect" is already starting to work, but then why is the sensor reading so small? When light is reflected from the walls twice, it will remain (0.9 * 0.9 = 0.81), three times 0.73, four times 0.66, and so on. Probably three times is the maximum that happens in the stead, but not sixteen to weaken to 0.2.
This is where the difference between the reflection in the box and the fiber is manifested, and the fact that the loss in the fiber is much less than 0.9 is not the main thing (the number of reflections in the box is not so large). The walls of the box, when reflected, also strongly scatter the light, that is, give it all sorts of directions.
What does the sensor measure? - light falling on it at an angle of 90 radii and light from 0 to 90 multiplied by the cosine of the angle (from 0 to 1). That is, not the whole value, such as a microphone (although most also depend on the direction) or a thermometer. And a small part of the light even comes from below reflected from the bottom.
It's just that the sensor does not catch all the light, as well as the human eye and the camera, and therefore it "works" ideally in these tasks.
Plants catch light in all directions inaccessible to the measurement of the sensor and this should be taken into account. For a complete picture, it is worth at least placing the sensor in the usual horizontal, vertical and inverted position to summarize the readings.
Last edited:
PadawanWarrior
Well-Known Member
Markshomegrown
Well-Known Member
That sounds about right, took all of this into consideration when designing and building my led, I added different size reflectors, changed the angles to get the best light spread from the bulbs, and spaced them apart 15cm ,18cm ,20cm ,22cm ,25cm to get the best out of the bulbs(overlapping light).
There are so many variables and you have so much control, you could build an led that gives you a perfect light spread.
Last edited:
dizzyground
Well-Known Member
@jimihendrix1 thats a good amount of growing 
How many hps bulbs have exploded or broken somehow that it creates a danger?
How many hps bulbs have exploded or broken somehow that it creates a danger?
jimihendrix1
Well-Known Member
Ive been growing with HID since 1977-78, and have yet to have 1 bulb explode on me. I know they can, but in my personal experience, Ive yet to have on explode, or break. Im always careful not to touch the bulb. and if I do, I wipe ot thoroughly with a clean cotton cloth, and I never foliar feed with the light on, and if I do foliar feed, I always wipe the bulbs down with a clean dry cotton cloth.
I also replace my bulbs every 70 days of veg on 24/7, and every 2 flowering cycles. This is for a single ended 1000w HPS/Hortilux
For a Dual Ended bulb I replace them every 6 months of 24/7, and every year of 12/12.
I think they say a DE bulb retains 90% of its power for a year, but Im not so sure, so I replace them more often.
A SE bulb loses 10% the first month, and then stabilizes.
I never had any fires, or close calls at all. I had a buddy that was in his grow room with no shirt on, and was sweating, and accidently bumped into a 1000w HPS and it exploded. It burned the shit out of him too. Water and HID are a bad mix.
I also replace my bulbs every 70 days of veg on 24/7, and every 2 flowering cycles. This is for a single ended 1000w HPS/Hortilux
For a Dual Ended bulb I replace them every 6 months of 24/7, and every year of 12/12.
I think they say a DE bulb retains 90% of its power for a year, but Im not so sure, so I replace them more often.
A SE bulb loses 10% the first month, and then stabilizes.
I never had any fires, or close calls at all. I had a buddy that was in his grow room with no shirt on, and was sweating, and accidently bumped into a 1000w HPS and it exploded. It burned the shit out of him too. Water and HID are a bad mix.
Markshomegrown
Well-Known Member
Going to stick with my led light bulbs, they can't explode or catch fire, can they?
always used 600w se bulbs, stored them in a sock, very worried about marks or scratches, I have been lucky, used well over 60 bulbs
jimihendrix1
Well-Known Member
Any driver/ballast can catch on fire. Is it likely?? Probably not, but when youre dealing with electricity, anything can happen.
I also have a 645w Gavita 1700e I use for veg.
I also have a 645w Gavita 1700e I use for veg.
Last edited:
calvin.m16
Well-Known Member
calvin.m16
Well-Known Member
I used a Apogee meter and my Philips 1000W DE HPS bulbs tend to last 12-14 months before I see a 10% degradation in PPFD.
I've used a $500 meter to confirm that you can just eyeball the Arc-Tube of the HPS lamp and if its dark brown at the ends or black/grey then its basically a visual indicator of the same performance loss.
