cxb3950 vs hps

About to do a side by side comparison 400 watts of cobs vs my 600w hps. Here is a couple pics of the crop that is flushing this week. After they come out I have same strains for each side of tent. Damn you people on this forum for getting me hooked on led !!

So whats your early opinion, how do they compare? From the pics it looks like the HPS has outproduced the LED by a fair margin.

bri77 said:

So whats your early opinion, how do they compare? From the pics it looks like the HPS has outproduced the LED by a fair margin.

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Kinda does, doesn't it?

looks like plants from the HPS side are stretching to the LEDs though... idk.

look forward to a final tally

which side do the plants that are right between that are getitng equal light from both fixtures go? seems like the hps would win handily because its covering about twice the area

I could be wrong but it looks like all the plants under the hps are leaning toward the cob's??

Or just flopping over? It hard to know whats going on tbh.

To be fair ,the cobs have only been in there since Veterans Day, I switched them out with another 600 watt HPS

bri77 said:

So whats your early opinion, how do they compare? From the pics it looks like the HPS has outproduced the LED by a fair margin.

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I did push a bunch of branches over to the cob side just to see if I could notice any difference since it was the same plant,

giantsfan24 said:

I could be wrong but it looks like all the plants under the hps are leaning toward the cob's??

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CobKits said:

which side do the plants that are right between that are getitng equal light from both fixtures go? seems like the hps would win handily because its covering about twice the area

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I'm just getting ready to cut these down this weekend and have clones of the same strain so I can do a fair comparison from the start. I also wanted to have 600 watts of cob to do a fair test but I ran out of money! All the led 'ers say as far as par watts go, it should compare. These lights do cost a bundle though and I still haven't paid my November rent because of them! Size definitely seems to be leaning towards the HPS side though but we'll have to wait till I get same strain clones in to be definitive. Thanks for lookin everyone!

we did one similar before , but it's not perfect comparation .Should do comparation under Two exactly the same environment。

Here's mine, 860W CDM for the plant on the left and 3500K COB LED on the right. The COB LED plant is about 2 weeks behind the CDM lit plant.

In the next test run do them in separate environments simply because if you had the temps in line for HPS you are too cold for the LED side. Optimum temp for LED is 5-6° F warmer than HPS.

Stephenj37826 said:

In the next test run do them in separate environments simply because if you had the temps in line for HPS you are too cold for the LED side. Optimum temp for LED is 5-6° F warmer than HPS.

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I've never read this (which may mean I'm uneducated lol). Why is this?

Temp at your leaves will be 5-6 cooler under LED than HPS given the same ambient temp. due to the radiated heat from HPS

No IR, so canopy temps are lower than ambient temperature.

Try doing separate grows COBS VS HPS, without any of the light interrupting each other. 600W COBS matching 600W hps.

giantsfan24 said:

I've never read this (which may mean I'm uneducated lol). Why is this?

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HID follows this basic rule. If you pump 1000 watts into an HID bulb 1000 watts of energy is coming out. In SE HPS case around 32-33% comes out as visible light or PAR(Photosynthetic Active Radiation) light. The rest comes out above 800 nm which isn't depicted in the spectrum graph on the box. This 800+nm "light" is actually infrared heat(same as comes out of most small electric radiant heaters). Led on the other hand is different. If you put 50 watts into a COB you get 25 watts of usable light and 25 watts of heat (just an example). The difference is the type of heat. The LED's waste heat is expelled off the back of the led into the heat sink where it is dissipated into the air. It doesn't have the heat soaking effect that HID has. So basically it's Radiant heat vs Compounding Conductive Heat.

Its just one reason informal "grow-offs" are not really valid ways to compare radically different lights. Do you keep both sides exactly the same, temps , canopy shape etc, and therefore favor one fixture over the other?

Constructing a valid grow off is a job for a trained scientist imo.

Stephenj37826 said:

Optimum temp for LED is 5-6° F warmer than HPS.

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Wouldn't that be dependent on total radiant watts and the coverage area?

You'd need to monitor temp at leaf and adjust accordingly to keep them equal.