How to apply DLI to your lighting

[BigJohnny]

Saw a video from Reefdudes on YouTube about this and it made me realize how often people give recommendations on PAR but not duration. First off, even if everyone ran the same duration, alk/nutrient levels/spectrum of the light source etc would all impact what ideal par for the coral is in your tank vs someone elses. But that can't exactly be calculated at this point in our hobby. DLI can, and it's how you should measure how much light your corals are getting.

300 PAR for 6 hours is obviously not the same as 300 PAR for 10 hours. One great example of applying this is the following:

Say you have radions and you know that tons of people have success with the SPS AB+ schedule with peak 300 PAR in as much of the tank as possible. You want to do that but then you realize it's only on for 9 hours total (I think, I don't have radions). You want a much longer photoperiod so you can enjoy the tank more, say 12 hours. Sure you could extend the ramp on either side but then your adding to the total amount of light the corals are receiving. You want to replicate proven results, so you adjust your intensity and duration so that the DLI is still the same. This is how i would do it:

1 hr ramp at 300 PAR = 1 x 50% × 300 = 150
7 hrs at 300 PAR = 7 x 300 = 2100
1 hr ramp at 300 PAR = 1 x 50% x 300 =
150

150 + 2100 + 150 = 2400 TOTAL for DLI

Then you can extend either your ramp or peak or both and just reduce your intensity so that your DLI stays at the same 2400 Total.

This should provide comparable results to running the standard SPS AB + at 300 par while still getting a 12 hr photoperiod. Now, there will be some minor differences in growth/coloration (not necessarily better or worse) but I think it's a great way to take a DLI from something that's proven from a tank with similar parameters and apply it to your tank.

I actually did this 8 months ago as a starting point on a new tank and used a par meter to set my 6 bulb ati sunpower + 2 Kessil a350ws to the 2400 total DLI like the SPS ab+ at 300 PAR.

Here's the video from @shiftline if you are curious:


Hope this helps some people

 

[justingraham]

Yea I think ur on the right track
And I get where you are coming from and they are I’m guessin just numbers you thought were good
But I beleive ur equation is wrong
DLI is measured in like 22 umol not 2400

It should be 300 ( par) x 7 (hours on)x 60 (seconds in a min)x 60( mins in an hour) /1 million(to make the number usable)
Which is a very low DLI of 7.56 you are shooting for roughly 20-25 DLI(again I’m thinking u just picked some numbers people tend to use)
(This is where I am lost because I can’t find any info on it what to do with the ramp up and down time do you add it I’m guessing yes)Then I’m guessin you would add the DLI of the ramp up time 150(half of 300 par) x 2 x 60 x 60/ 1 million
Which is a DLI of 1.08 +( 7.56)
So you would still get a very low DLI of 8.64

If u get time this article is very interesting helped me understand a lot about DLI and made me extend my light time to get that DLI in the 20’s
Can’t wait to watch this video tho

https://www.advancedaquarist.com/2013/9/aafeature

 

[BigJohnny]

Yea I think ur on the right track
And I get where you are coming from and they are I’m guessin just numbers you thought were good
But I beleive ur equation is wrong
DLI is measured in like 22 umol not 2400

It should be 300 ( par) x 7 (hours on)x 60 (seconds in a min)x 60( mins in an hour) /1 million(to make the number usable)
Which is a very low DLI of 7.56 you are shooting for roughly 20-25 DLI(again I’m thinking u just picked some numbers people tend to use)
(This is where I am lost because I can’t find any info on it what to do with the ramp up and down time do you add it I’m guessing yes)Then I’m guessin you would add the DLI of the ramp up time 150(half of 300 par) x 2 x 60 x 60/ 1 million
Which is a DLI of 1.08 +( 7.56)
So you would still get a very low DLI of 8.64

If u get time this article is very interesting helped me understand a lot about DLI and made me extend my light time to get that DLI in the 20’s
Can’t wait to watch this video tho

https://www.advancedaquarist.com/2013/9/aafeature

You are correct in that I actually have no idea what DLI is but the concept I'm using is basically par x hours = total par for the day lol. I probably should have researched DLI first but regardless it's the same idea.

Curious where you got 20-25 DLI though and whether your calculations are correct, if the sps ab+ at 7 hours + 1 hour ramp on both ends (not just one so it would be 9.72, not 8.64) is so low, because tons of people have success with that. I do not think that is very low at all for a reef tank and I would not recommend more than doubling that to get above 20. 600 par for 14 hrs with a 1 hr ramp on either side? That would fry my tank immediately.

Are you sure your calculating that properly? I haven't read the article but will later.

 

[justingraham]

You are correct in that I actually have no idea what DLI is but the concept I'm using is basically par x hours = total par for the day lol. I probably should have researched DLI first but regardless it's the same idea.

Curious where you got 20-25 DLI though and whether your calculations are correct, if the sps ab+ at 7 hours + 1 hour ramp on both ends (not just one so it would be 9.72, not 8.64) is so low, because tons of people have success with that. I do not think that is very low at all for a reef tank and I would not recommend more than doubling that to get above 20. 600 par for 14 hrs with a 1 hr ramp on either side? That would fry my tank immediately.

Are you sure your calculating that properly? I haven't read the article but will later.

Yes I got the DLI number from Dana riddle himself
And no I did it properly for the ramp up I multiplied 150 x 2 x 60 x 60/1 million
And the equation to get DLI is in the article I attached
Read the article it’s a good one and most of ur questions are answered in it
and I would say most people run there lights for 12 hours with ten of it being at 100% and two hours of ramping

 

[BigJohnny]

Yes I got the DLI number from Dana riddle himself
And no I did it properly for the ramp up I multiplied 150 x 2 x 60 x 60/1 million
And the equation to get DLI is in the article I attached
Read the article it’s a good one and most of ur questions are answered in it
and I would say most people run there lights for 12 hours with ten of it being at 100% and two hours of ramping

I made a mistake I meant to say doing DLI that way with sps ab+ at 300 par would have the peak at 14+ hours at 300 par (not 600) with a 1 hour ramp on either side. That's just not going to work for most people imo. That is a ton of light and double what wwc and reef wholesale use essentially along with tons of people having great success using stock sps ab+ at 300 par average throughout the tank.

You recommend most people run their lights for 12 hours with 10 at 100% but do not provide a par number for that 100%. That was the reason I made this thread is to explain why we should all avoid either just par or just duration recommendations. It's not the whole picture. What par and DLI are you recommending with that schedule?

I'll read the dana riddle article and see how he gets to that DLI, but I would rather shoot for half of that target of 20 like wwc and reefwholesale running sps ab+ have had success at. I did the math on Jason fox too and his is similar to wwc and way below that 20. Now maybe that 20+ dli would work in a 12 dkh tank with high nutrients like Sanjays, but for average reefers params that seems very high imo.

 

[BigJohnny]

I read the article, I'm not sure if you know this but the corals he was studying in that tide pool were shutting down photosynthesis for most of the day because they were receiving too much light. Just because it was there doesnt mean its ideal.

It also doesn't appear to recommend that DLI just says that's what it is and how you would be matching it in aquarium.

I personally would rather target DLI of successful aquaculture facilities rather than a tide pool analysis in Hawaii.

I am not here to debate proper DLI though, so let's move past that. I was just showing that PAR alone is not enough. If people want too match the light of someone else's tank (or a tide pool in hawaii) they need to know duration as well, which we agree on.

 

[justingraham]

I read the article, I'm not sure if you know this but the corals he was studying in that tide pool were shutting down photosynthesis for most of the day because they were receiving too much light. Just because it was there doesnt mean its ideal.

It also doesn't appear to recommend that DLI just says that's what it is and how you would be matching it in aquarium.

I personally would rather target DLI of successful aquaculture facilities rather than a tide pool analysis in Hawaii.

I am not here to debate proper DLI though, so let's move past that. I was just showing that PAR alone is not enough. If people want too match the light of someone else's tank (or a tide pool in hawaii) they need to know duration as well, which we agree on.

Yea I know and his DLI was 34 in the tide pool he said in one of the post this website 20-25 is a good DLI to go after in an aquarium

not here to argue either this subject peaked my interest that’s all and was trying to give u the info that was given to me from Dana

 

[BigJohnny]

Yea I know and his DLI was 34 in the tide pool he said in one of the post this website 20-25 is a good DLI to go after in an aquarium

not here to argue either this subject peaked my interest that’s all and was trying to give u the info that was given to me from Dana

I'm glad we're on the same page! I know you weren't trying to argue I just didn't want you to think I was/get too far off topic.

What we agree on is that people should be using actual DLI or my bootleg DLI (aka multiplying par by hours lol) to set up or adjust their light intensity/photoperiod to match whatever tank/study/aquaculture facility they desire's total light energy, not just PAR.

Many vendors recommend specific par for certain corals. That's fine but they should say what photoperiod they recommend with that too.

Now, I'm not saying that 6 hours at 300 par will produce identical growth and coloration as 1 hour at 1800 par, obviously not, but for more minor adjustments it should produce very similar results. There are obviously many other factors like photo saturation/inhibition points, coloration in response to various intensities, etc. It's a good starting point however and much better than someone simply recommending "300 par" and then going with a photo period that's popular or that they want.

Of course this also doesn't take into consideration water parameters, bioload, flow, etc. But that's a whole nother can of worms. I also wanted to share that video because the guy from ecotech talks about a study they will be releasing soon about applying equal DLI to different set ups with different photoperiods/intensity and getting very similar results, except for some things like growth pattern of montis which I'm looking forward to reading about.

 

[Charlie’s Frags]

There’s a member here who sent me a video of his homewrecker colonies. Colonies. His photoperiod is 1 hr ramp up, 5 hours peak, 1 hour ramp down. 7 total hours of light. That’s it. Just saying.