@Venturi, my friend, I think you should be one of the best who can explain this.
In the quote in the picture, I understand the DLI is calculated with the ppfd x light x hour x day.
But then why are they using those numbers as an example?
And what does it mean “there is been a tradeoff between ppfd and…?”
(to long😆)
Thank you for anyone who wants to join in to help.
3 Likes
Hello, my friend!
The daily light integral (DLI) is the total number of photons (measured in mols) per square-meter a light emits each day.
The units for PPFD are µmol per second per meter². So, the first step is to convert to µmol per day per meter². To do this, we multiply the PPFD by the number of hours per day the light is on and the number of seconds in an hour (i.e., 3600). Suppose the measured PPFD is 500 and you’re using an 18/6 light schedule:
500 µmol/s/m² x 18 hours/day x 3600 s/hour = 32,400,000 µmol/day/m².
The last step is to convert from µmol to mol. There are 1 million µmol in 1 mol, so we divide the previous results by 1 million:
32,400,000 µmol/day/m² / 1,000,000 = 32.4 mol/day/m².
Thus, the DLI for this example is 32.4.
Putting it all together:
DLI = PPFD x Hours x 0.0036 ,
where Hours is the number of hours the light is on each day.
The “tradeoff” is the one between PPFD and “lights on” time. That is, you can achieve a desired DLI by using a high PPFD and short on-time or by using a lower PPFD and a longer on-time.
PS - Do you have a favorite style of pizza?
7 Likes
Should also be noted that calculating your dli properly requires ppfd average.
7 Likes
Mamma mia!
Your knowledge it’s impressive, thank you, truly.
Ok, it’s clear; when I read it, I understand; to remember it, I have to apply it, but the concept is clear.
I hardly ever checked the DLI, only ppfd, but since you told me about checking it in a previous post, I took notice. I would say that, right now, my big girls are flowering beautifully, but the DLI is too high, even if the PFD is within.
I use the App to check the values; I don’t think they are very accurate; I would need to buy a decent one.
Anyhow, now I at least know what that formula means and can try it.
Thank you again, 
My favourite pizza? If it is well made, a Margherita is still one of the best; when I put ingredients on, I don’t put too many; the point is to eat a pizza with toppings, not toppings with a pizza.
If I buy a Frozen one, only Margherita.
If I can make it myself, I like caramelised onion, premium mushrooms and goat cheese. I also like artichokes, olives, and smoked cheese.
I like the thin North Italy style or deep pan, again, when is well-made 
3 Likes
Here’s an example of how the tradeoff I mentioned can be used to advantage:
Awhile back, I was running some photoperiods 18/6 in veg at an average (thanks @dbrn32 
) PPFD = 1000. That gave me a DLI = 65. I’d made “lights out” time occur in the afternoon, but the tent’s temperature would still drop below 70° F.
So I changed to a 24/0 schedule at 750 PPFD. That still gave me a DLI = 65 and, by keeping the lights on, the temperature in the tent stayed in the upper 70s/lower 80s at all times.
In fact, because the average temperature was higher, I was able to boost the PPFD (and DLI) further.
Have you ever encountered a deep dish pizza in Italy? I have the idea that’s a Chicago invention.
2 Likes
Yes…, ive got it.
It takes me a moment, and I reread certain passages, but I understand everything.
I never even associate temperature with PPFD and DLI, but it makes perfect sense.
I mean, if the temperature becomes an issue, of course, it is possible to obtain a higher or lower temperature by manipulating the PPFD.
A light with a dimmer is needed tho.
1 Like
Thank you for the reply.
I have heard of it, but idk what it is, the ppfd avarage.
2 Likes
The deep pan, yes, in Italy they make deep pan pizza, they are the “Pizza al taglio”, They are small takeaway shops, they mostly make deep pan pizza, they have also been around for a long time, 45 years the least.
One of my friends I was working with, makes a wonderful North Italy thin base but also a great deep pan, both yummy,
I tell you something: as long as the food is well made and with good ingredients and good equipment with pizzaioli or a Chef who knows what to do, almost every food, it’s good, so, the deep pan can be really nice if done properly 
2 Likes
It’s the average light intensity across the entire space for the entire duration of the light cycle. In an outdoor grow no matter where on the plant you measure the ppfd will be about the same at any given time, but the intensity will increaae from first light until mid day then start decreasing again. Dli is calculated using the average intensity not the ppfd at the highest measured part of the day. Infoor grows don’t usually have the issue eith varying intensity throughout the day but they do have varying levels of intensity across the canopy from artificial light. So you need to find the average intensity across the entire canopy and not simply use the point that measures the highest.
The image below shows an hlg-65 mrasured at 12" in center of 2x2 has ppfd of 400 umols/s. But 12-15" away it’s as low as 120 umols/s. The ppfd average of this space is significantly lower than the 400 umols/s measured directly under the center of the light.
2 Likes
Is that a problem for you? I forget what lighting unit(s) you have.
I don’t know whether deep-dish was invented independently in Chicago or inspired by the Italian take-away shops, but I’m regretting having raised the subject because I’m jonesing for a good pizza now and my private jet is in the shop! 
1 Like
…and just to drive home how important is the quality, particularly of ingredients, here it’s an example:
Think of some deep-pan pizza.
Cheese a galore, so the top it’s just a swamp of oil and cheese, tomato sauce full of chemicals and spices to give flavour to a crappy basic tomato sauce,
The dough and the base are chewy and heavy.
Now, a good pizzaiolo is going to be able to make a soft, airy dough in the middle e, crunchy around and at the bottom.
Good quality tomato sauce (tinned it’s fine, but it should be the least a decent quality)
Blizzed together with a few fresh basils, extra virgin olive oil and a couple of spices, that’s it.
Not too much mozzarella and the mozzarella for pizza is better, but any cheese or other ingredients are ok; it’s important. It’s the quality of the ingredients and put sparsely on the pizza.
I am vegetarian now, but I always put ham on my pizza, real ham, cut from the leg.
Good ingredients cooked properly equal good food.
You’d think it would be obvious, but…
2 Likes
I have a dinmer 100 75 50 25 x cent
1 Like
Good morning @ACMilan ,or evening for you.
1 Like
.
I know how you feel; many times, I think about a nice pizza.
The Chicago is a deep pan with some characteristics aside, like the quantity of cheese and the kind of cheese, it looks like they are cooked differently; in Italy, they are higher and softer and sold in squares.
But probably a good Chicago-style pizza. It’s good if made properly, but still very fatty tho.
2 Likes
Hello, thank you, I truly appreciate it.
I am going to read it better later.
I had a quick read-through, and I understood but I need to concentrate more.
hank you
1 Like
Hello @SausageMahoney, 7 hours ago, it’d have been 2.30 pm, so Good Afternoon was more proper. 
1 Like
Is evening and afternoon not the equivalent in Italian as is in Español?
1 Like
No it isn’t…
Buona notte… 
1 Like
Did you mean the same words?
1 Like
I was thinking incorrectly… I work with a ton of Mexicans so I’m roughly learning Spanish and saw the languages were similar in some instances.
1 Like