Lighting --- Comparing Old to New Rules

[PharmrJohn]

Sorry for this question, but I gotta ask. In the old days, you had a choice between Halides and T5s. I chose T5s. The ONLY rule was to follow 5W/G as your baseline. I had a 90g tank do I procured a Tek 8x54W fixture. It fit the bill in terms of math.

Now, it doesn't seem as easy. I admit, I know nothing about LED fixtures, the different models, companies, etc. etc. So what are the rules now? Is there still a 5W/G rule or is that considered truly outdated now? TIA. J.

 

[KrisReef]

THe only rule I remember is 2lbs/gallon for live rock. That has been tossed out with time. I think the best way to measure light is Par and lots of light folks say that isn't the best way either, go with PUR?

THe Rules is more like guidelines!

Let's see what the other players come up with?

 

[crazyfishmom]

Interesting on 5W/G… I think I’d fry my tank if I tried to do that with LED or I’d have to dim them quite a bit. For LED if you are trying to grow acros it seems like 150 W for 24 x 24 seems to be a general guidance based on manufacturer recommendations for their lights (based on looking at various light fixtures on the market). LEDs also create hot spots whereas T5 covered spaces more evenly… just too much information and too way over my head for the most part. Learning something new every day for sure!

 

[PharmrJohn]

THe only rule I remember is 2lbs/gallon for live rock.

Yep. I remember that too. I had about 145# in a 90g and I wasn't done (before my tank crashed and I quit for awhile). It was piled up where-ever I could put it, mainly on the back glass. Forget about cleaning behind it.

 

[fish farmer]

THe only rule I remember is 2lbs/gallon for live rock. That has been tossed out with time. I think the best way to measure light is Par and lots of light folks say that isn't the best way either, go with PUR?

THe Rules is more like guidelines!

Let's see what the other players come up with?

I couldn't tell you how many lbs of rock I have now....I just scaped it so it looked good.

I did 4 watts per gallon back in the day. High light coral up top, mushrooms down below.

I pretty much do the same now, I keep ramping up both the led and t5s and see how corals respond.

 

[ISpeakForTheSeas]

Yeah, there's not really a set rule these days, but looking at PAR and spectrum seems to be the way to go.

the Spectral Power Distribution Chart/Graph (shows basically how much of each color of light is produced by the fixture) and PPFD Chart (basically a map of the PAR output of the fixture).

Yes, PUR is theoretically better, but the problem is that what part of the spectrum is "useable" (the "U" in PUR) is going to vary from one species to another and be highly dependent on other variables (such as what lighting a coral is photo-acclimated to, what clade of zooxanthellae it has, etc.), so what is "useable" may well vary even between specimens of the same species.


My general recommendation is to get a good, full-spectrum light that leans heavy on the blue side; what PAR you want depends on the corals you want to keep, but the general recommendations with LED's seems to range from ~50-450 PAR depending on the coral (some special specimens like certain clams or anemones may need higher).

Also, just as a note, while looking at wattage may (or may not) work for the big name companies in the hobby, it's not always a good way to gauge the strength (PAR) of an LED fixture - so I always suggest looking at the PPFD and Spectral charts:

With regards to watts and the function of the light: watts not always useful for determining if a light is good or how powerful it is - for example, I know of one LED company that markets two lights with the exact same specs, but one is 600 watts and the other is 1000 watts; they admit that there is literally no other difference between the two lights (they have the same PAR, spectrum, features, and everything), so going with the "more powerful" 1000 W literally just raises your electric bill with no benefits over the 600 W).

 

[PharmrJohn]

Yeah, there's not really a set rule these days, but looking at PAR and spectrum seems to be the way to go.

Yes, PUR is theoretically better, but the problem is that what part of the spectrum is "useable" (the "U" in PUR) is going to vary from one species to another and be highly dependent on other variables (such as what lighting a coral is photo-acclimated to, what clade of zooxanthellae it has, etc.), so what is "useable" may well vary even between specimens of the same species.


My general recommendation is to get a good, full-spectrum light that leans heavy on the blue side; what PAR you want depends on the corals you want to keep, but the general recommendations with LED's seems to range from ~50-450 PAR depending on the coral (some special specimens like certain clams or anemones may need higher).

Also, just as a note, while looking at wattage may (or may not) work for the big name companies in the hobby, it's not always a good way to gauge the strength (PAR) of an LED fixture - so I always suggest looking at the PPFD and Spectral charts:

Gotcha. That makes sense. Except for the 600W and 1000W fixture comparison. I mean, I understand, but wow. I've already honed in on a Reef Breeders fixture (x2) but I lacked the understanding of the hardware. To be able to choose spectrum is just fascinating to me. I guess it's really no different than choosing bulbs for my old T5 fixture. But the dialing up and down of intensity is a very cool concept for me.