A Taste Of Chocolate And Blueberries With Vipar Spectra XS 1500 Pro

[Carmen Ray]

Thank you Shed.

First you would need to know what your light is putting out in PPFD. The Vipar charts would be helpful here if you don't have a meter, since that will at least get you a ballpark.

I use the Photon app, which I have calibrated to the lights.

Once you have that number, you would go here:

Converting PPFD to DLI

Quantum Sensors measure measure the instantaneous photosynthetic photon flux density in µmol m-2 s-1. Use Calculator below to convert instantaneous PPFD µmol m-2 s-1 to DLI photosynthetic photon flux density in mol m-2 d-1 Enter PPFD : Enter Hours : DLI:

horticulturelightinggroup.com

and enter that PPFD and the number of light hours for that day (since your hours of electricity vary so much).

I entered some numbers to see how it works.

100% may be best if you average your DLI over time, since there are days you might be well under with 12 hours of shedding, but the plants don't care about your average and you may find that 100% pisses them off, so may need to crank it up or down depending on how many hours a day you think you'll get.

Do you mean vary the intensity according to how many hours the lights will be on?

LKA uses this chart as a guide:

Is the chart saying that as the plant ripens one must reduce the DLI? It looks like the DLI is reduced in the last three or so weeks of the plant's life?

 

[InTheShed]

I use the Photon app, which I have calibrated to the lights.

I entered some numbers to see how it works.

And?

Do you mean vary the intensity according to how many hours the lights will be on?

Indeed I do. If your lights will only be on for 12 hours one day then the plants might be able to handle a higher PPFD for that shorter amount of time - if will help them hit the DLI for that day.

Is the chart saying that as the plant ripens one must reduce the DLI? It looks like the DLI is reduced in the last three or so weeks of the plant's life?

That's pretty much what all the DLI charts say, and I know that @LKABudMan does it. It might be related to the dimming of the sun as it approaches winter.

 

[Carmen Ray]

And?

I may be understanding things incorrectly but it looks like I have been giving my plants too much light. I have had my lights on at 100 % intensity 24/0 for the duration of flower. It looks like they require less to meet DLI. This is what the Vipar chart suggests but I imagine that it must be at the correct DLI so that would affect the number of hours the lights are on, is that correct?

 

[StoneOtter]

You may have been Carmen. I've been doing the same and my next grows am going to give it a go to trust DLI numbers! I have to get a better understanding of all that!

 

[Grand Daddy Black]

Carmen, if I were in your position -- meaning running autos and dealing with recurring outages -- I would not care a whiff about DLI. In fact, I'd prolly run the lights 24/7 for most of the grow (not in the seedling stage, but in veg and flower).

I used to run my autos 20/4 throughout veg & flower (with no power outages to worry about). They did fine without reduced DLI at the end. Of course, that is not to say that they would not have done better with reduced DLI near the end.

 

[Carmen Ray]

You may have been Carmen. I've been doing the same and my next grows am going to give it a go to trust DLI numbers! I have to get a better understanding of all that!

I'd like to also but it might be a bit much to have to calculate and compensate each day and GDB's advice is probably spot under the circumstances.

Carmen, if I were in your position -- meaning running autos and dealing with recurring outages -- I would not care a whiff about DLI. In fact, I'd prolly run the lights 24/7 for most of the grow (not in the seedling stage, but in veg and flower).

I used to run my autos 20/4 throughout veg & flower (with no power outages to worry about). They did fine without reduced DLI at the end. Of course, that is not to say that they would not have done better with reduced DLI near the end.

That's all the persuasion I need

 

[InTheShed]

That's all the persuasion I need

Does that mean I don't need to reply to this?

I may be understanding things incorrectly but it looks like I have been giving my plants too much light. I have had my lights on at 100 % intensity 24/0 for the duration of flower. It looks like they require less to meet DLI. This is what the Vipar chart suggests but I imagine that it must be at the correct DLI so that would affect the number of hours the lights are on, is that correct?

In case it matters, 550 PPFD for 24 hours puts the plant at ~45 DLI, which is pretty much where the chart maxes out. I don't know how high off the plants you have your light but at 11" that would puts you in the 50% power range.

No idea how often you have 24 hours of electricity (if ever).

 

[Roy Growin]

Does that mean I don't need to reply to this?

In case it matters, 550 PPFD for 24 hours puts the plant at ~45 DLI, which is pretty much where the chart maxes out. I don't know how high off the plants you have your light but at 11" that would puts you in the 50% power range.

No idea how often you have 24 hours of electricity (if ever).

Does that mean if my ppfd is +/- 900 for 12 hrs it's a DLI of 40-45? Is that good/enough Shedster?

 

[Carmen Ray]

Does that mean I don't need to reply to this?

Nope, never. Your opinion always matters

In case it matters, 550 PPFD for 24 hours puts the plant at ~45 DLI, which is pretty much where the chart maxes out. I don't know how high off the plants you have your light but at 11" that would puts you in the 50% power range.

I kept the lights at 11 inches during flower. During veg I was trying to get the plants to stretch so I kept the lights further away. Am I understanding correctly if I think you are saying that at 11 inches away I'd only need 50 % power in a 24 hour period to achieve 45 DLI, theoretically speaking?

No idea how often you have 24 hours of electricity (if ever).

We do sometimes have a few weeks of no loadshedding or of stage 2 which generally means about 2.5 hours outage per day. However, most of the time we are between stage 4 and stage 6, when we have outages for up to 12 hours a day.

If I have understood you correctly, I could save a bit on electricity if I were to turn down the power on days when we have little to no loadshedding, and turn it back up when we are at stage 6?

 

[InTheShed]

Does that mean if my ppfd is +/- 900 for 12 hrs it's a DLI of 40-45? Is that good/enough Shedster?

900 for 12 hours is 38.8 DLI, so that's a bit under the auto chart max, but you also have to read your plants and see what they can take.

This is a chart for photoperiod plants, which maxes out close to 50:

Here is a post on DLI if anyone is in for more details.

 

[InTheShed]

I think you are saying that at 11 inches away I'd only need 50 % power in a 24 hour period to achieve 45 DLI, theoretically speaking?

That's the theory!

If I have understood you correctly, I could save a bit on electricity if I were to turn down the power on days when we have little to no loadshedding, and turn it back up when we are at stage 6?

If you're growing using DLI as a guide then absolutely. I dropped the wattage of my light when I saw my DLI was well above the auto chart.

I don't claim to have ever tested the DLI charts to see if they're correct, but I'm acting under the assumption that someone has in order to create them!

 

[Carmen Ray]

That's the theory!

If you're growing using DLI as a guide then absolutely. I dropped the wattage of my light when I saw my DLI was well above the auto chart.

I don't claim to have ever tested the DLI charts to see if they're correct, but I'm acting under the assumption that someone has in order to create them!

I shall have to ponder this a while. The thought of saving on electricity cost is tempting. I could try it and see how it goes. So I'd keep the power at 50 % and the lights on 24/0, and then when we get hit with heavy loadshedding I compensate by raising the power.