AquaIllumination PAR Measurements

[CalmSeasQuest]

Originally Posted by drtrash

Tom,
Not that it surprises me but there is no metion to the 70 deg optics on their web, I have seen 40 deg not sure if it's liturature or the AI web. Very positive. I placed an order for 2 blue sol units. Might need a PAR meter to dial in. I would asume AI should have other color pucks in the works as well.

I think the 70 degree optics are brand new, It would not have even come up if we weren't discussing retrofitting my Gen2 AI's.

Originally Posted by jonnybravo22

what good is a PAR meter if it is inaccurate on what you're testing (BLUE LED LIGHT)!!!??

geez, is there no reliable measure?

by the way, my LFS happened to have a PAR meter and i had them check the output at the red planets they had there, deep red color and deep green base , same frag tank i got mine from. the par at the frag was only 115 (Tek T5 setup, mostly aquablue +)

so i thought that was interesting.

If I understood Sanjay correctly, all PAR meters understate PAR when measuring large amounts of blue light - Just add 15% and you'll likely be close. That's very interesting about the Red Planet and 115 PAR - Perhaps we're just hitting it with too much light. I might try moving mine down a bit to see the results.

Originally Posted by jonnybravo22

btw do you keep the lights on at night for moonlights?

i have started turning the lights completely off at night b/c i was worried that I've been bombarding the corals 24/7 nonstop w/ light, even though i had the lights down to 1 or 2% as moonlights.

i started to think (and maybe read somewhere) that total darkness is helpful for corals to recovery from a day of being bombarded with PAR.

I use 2% blue with the moonlight program in the AI controller - it's replicates actual moon phase, varying the intensity, included going dark when no moon is present.

Originally Posted by Revenant42

Would it be possible to light a 95g mixed reef (with SPS 18" down and above) with two of these maybe turned sideways?

More than likely - yes. The AIs put out so much par, you could easily raise them to provide sufficient coverage and have plenty of PAR at depth (Chris mentioned they were looking at options for sideways mounting.)

[jonnybravo22]

I'm getting kinda ticked off tonight so apologies if i'm threadjacking.

if the AI lights are missing the spectrum needed for coral colors i'm pretty peeved!!!

looking at my corals (little over 1 month under AI LEDs, all had super colors when i brought home from LFS), the 1 color that really comes out is blue.

my borealis has great blue tips. it's holding a green color, but kinda brownish green lately.

my joe the coral has super blue tips. i mean they really glow. but it has lost it's florescent green glow and my plum crazy which was a deep purple has faded and is bascially blue now to the extent it has color. blue tips.

red planet has faded and is pink. my blue gigantea looks nice, but then again it's blue!!

Tom is it your view that these lights can only support blue animals b/c it doesnt have red or green peaks?

what is worse is that even the new AI modules (which they want you to pay hundreds of dollars for right after you just bought the unit!!!!) only adds more blue. not really much more purple, or red or green? T5s are calling my name, should i listen?

seems like the other LED guys are adding different specturm. AI is going to be left behind if they dont offer a solution that can support different colors of corals.

Tom you're good about responding to points, wonder what you think of the above. (getting anxious cuz i waited so long to get these lights and spent a #@% ton of money on them and now i'm sitting here wondering if i'm going to have to buy another type of lighting to get true healthy color from the corals.)

by the way not to just rag on the lights, perhaps there are water chemistry adjustments that would help with color -- i'm just saying, :P if it doesnt have the right spectrum that kind of sucks.

[CalmSeasQuest]

Originally Posted by jonnybravo22

if the AI lights are missing the spectrum needed for coral colors i'm pretty peeved!!!

looking at my corals (little over 1 month under AI LEDs, all had super colors when i brought home from LFS), the 1 color that really comes out is blue.

my borealis has great blue tips. it's holding a green color, but kinda brownish green lately.

my joe the coral has super blue tips. i mean they really glow. but it has lost it's florescent green glow and my plum crazy which was a deep purple has faded and is bascially blue now to the extent it has color. blue tips.

red planet has faded and is pink. my blue gigantea looks nice, but then again it's blue!!

Tom is it your view that these lights can only support blue animals b/c it doesnt have red or green peaks?

what is worse is that even the new AI modules (which they want you to pay hundreds of dollars for right after you just bought the unit!!!!) only adds more blue. not really much more purple, or red or green? T5s are calling my name, should i listen?

seems like the other LED guys are adding different specturm. AI is going to be left behind if they dont offer a solution that can support different colors of corals.

Tom you're good about responding to points, wonder what you think of the above. (getting anxious cuz i waited so long to get these lights and spent a #@% ton of money on them and now i'm sitting here wondering if i'm going to have to buy another type of lighting to get true healthy color from the corals.)

by the way not to just rag on the lights, perhaps there are water chemistry adjustments that would help with color -- i'm just saying, :P if it doesnt have the right spectrum that kind of sucks.

Lots of points -

First, I LOVE my LEDs, I have 3 different Mfgs over 3 diff tanks - all produce subtle differences in color. Of the three, the AI's are IMHO the best of the lot.

While I do believe there is more to learn about replicating the perfect spectrum to produce optimal colors, I would not go back to MH or T5s.

Different doesn't mean bad - While I (and many others) struggle to get the brightest reds - my blues, yellows, pinks, oranges and greens are off the charts - far brighter than I could produce with other lighting. Typical ORA pieces morph into spectacular versions not possible able under other lighting. i.e. I have ORA Borealis that is the brightest neon gold with electric blue tips - far prettier than the non-led version.

Most importantly - IMHO, the biggest factor in new LED owners complaining about lack of color is we initially BLAST everything with too much PAR. I adjusted my AI's to match the "visual appearance" of the MH/T5 setup they replaced and proceeded to cook everything in the top third of my tank. It's taken me many months to begin to regain colors - and along the way I played with carbon dosing, which adds yet another variable to the color story.

I think we're about 95% there and it won't be long until the missing spectral spike is identified and accounted for by simply swapping out a few LEDs.

The quest for perfect coloration aside, when considering all other aspects (massive PAR, growth rates, thermal and electrical efficiency, compact size, 10+ year bulb life, "greenness", dimming, variable optics supporting multiple mounting options...) LED's are well ahead and I believe they will eventually represent the bulk of reef lighting - at least until Plasma coloration issues are resolved.

To support my point, all one had to do was observe what lighting technologies took center stage at MACNA. I saw no "game-changing" advances in MH, T5 or Plasma (save perhaps the 95 watt VHOs which unfortunately did not survive shipping.) LEDs were quite simply everywhere.

My advice is to be patient. I've been going through the LED learning curve for about a year and still have much to learn about optimal PAR and white/blue settings - It's a challenge, but I like pioneering After all, if it were easy - anyone could do it

[jsousa]

Tom,

Agree with all your points. LED is the obvious way to go. Too many pluses.

Anyway, do you have any pics of you tanks? I'm actually interested in how you mounting the AIs. I need to do it with aesthetics in mind. I was actually go to build a mount for them as opposed to hanging from the ceiling or ruining the rimless look of my new Reef Savvy 50 gallon. Any pics from anyone would be greatly appreciated.

[jonnybravo22]

my mounting system.

[jonnybravo22]

appreciate the reply Tom. I have had the LED lights for about 8 months but have only had these corals for about a month.

it seems like some people have to just wait a while after corals switch to LEDs and a few months of adjustment later the corals come out? I just bought an apogee PAR meter so i will be doing extensive adjustments to basically match the exact specs of the frag tank the LFS has the corals in since they looked so amazing there and have been lackluster in my tank. Perhaps 100% blue at the height i have the lights is too much, even with very little white. I'll test it out soon enough.

Originally Posted by CalmSeasQuest

Lots of points -

First, I LOVE my LEDs, I have 3 different Mfgs over 3 diff tanks - all produce subtle differences in color. Of the three, the AI's are IMHO the best of the lot.

While I do believe there is more to learn about replicating the perfect spectrum to produce optimal colors, I would not go back to MH or T5s.

optimal is one thing -- i'm just talking about GOOD. ya know?

Different doesn't mean bad - While I (and many others) struggle to get the brightest reds - my blues, yellows, pinks, oranges and greens are off the charts - far brighter than I could produce with other lighting. Typical ORA pieces morph into spectacular versions not possible able under other lighting. i.e. I have ORA Borealis that is the brightest neon gold with electric blue tips - far prettier than the non-led version.

interesting point here, b/c i have a Borealis that is about the only one holding it's color. though it's still browning a little, it's still pretty green and has nice vibrant blue tips. Yours turned golden? Recent pics?

Most importantly - IMHO, the biggest factor in new LED owners complaining about lack of color is we initially BLAST everything with too much PAR. I adjusted my AI's to match the "visual appearance" of the MH/T5 setup they replaced and proceeded to cook everything in the top third of my tank. It's taken me many months to begin to regain colors - and along the way I played with carbon dosing, which adds yet another variable to the color story.

i'm curious to see if this is what the PAR meter tells me i've been doing. i'll know soon enough. If so i'll ratchet down the intensity and see if that solves the problem


I think we're about 95% there and it won't be long until the missing spectral spike is identified and accounted for by simply swapping out a few LEDs.

that would be good IMO. I dont want to change my lighting system and have to buy more stuff. but what sucks is that AI seems to have just gone more blue, completely ignoring the red end of the spectrum. and in fact there's not really much more purple in the RB either (a little but it's not violet). I asked Clough about this and he basically said purple isnt going to happen with his LEDs, so if that's part of the required spectrum,.... this guy is an engineer, it just doesnt feel like they are aware of what works for corals. they need to get some people on the staff that actually have nice reef tanks that use their lights so they can figure out works and show it off.

The quest for perfect coloration aside, when considering all other aspects (massive PAR, growth rates, thermal and electrical efficiency, compact size, 10+ year bulb life, "greenness", dimming, variable optics supporting multiple mounting options...) LED's are well ahead and I believe they will eventually represent the bulk of reef lighting - at least until Plasma coloration issues are resolved.

i think these are all great aspects of the LED lights, and that's why i dont want to move to another format.

To support my point, all one had to do was observe what lighting technologies took center stage at MACNA. I saw no "game-changing" advances in MH, T5 or Plasma (save perhaps the 95 watt VHOs which unfortunately did not survive shipping.) LEDs were quite simply everywhere.

yeaaaaah, i hear you but a fad doesnt mean it's a good thing. think crocs

My advice is to be patient. I've been going through the LED learning curve for about a year and still have much to learn about optimal PAR and white/blue settings - It's a challenge, but I like pioneering After all, if it were easy - anyone could do it

Yes. i hope this is the answer -- just being patient and using my new PAR meter to make adjustments. if that gets me the colors back I will be sooo happy with the LEDs b/c all the other features are great (controllability, no heat transfer, compact size, etc.)

Thank you again for responding and i'd love to see your golden borealis, maybe i misread your post, seems like a unique color. mine is slightly browning, wonder if it's headed that way.

i'll try to contribute to this thread when PAR meter comes in. would love to be able to show off a 'successful' LED SPS tank.

[reefsurfing]

Originally Posted by jonnybravo22

my mounting system.

Is that a TV mounting bracket?

[wesley6610]

jonnybravo22, it sounds like you have learned some of the heartache of being an early adopter, but this is how innovation starts. When I did my DIY unit I bleached my entire tank in like 3 weeks, not knowing what was happening and that my current was too high and optics too tight. It doesn't mean that you wasted your money, but you must now fine tune your lights, coral placement, fixture height and possibly LED pucks to meet the needs of your tank. It can be a bit overwhelming, but that's why we do this hobby to begin with. If I were using AI's, I would raise that fixture at least 6 - 8 inches higher than you have it and keep it at the existing intensity that you have it. Perhaps see about some T5 supplementation for the colors that you are use to seeing. So maybe you need to add a midday bulb to help bring back some colors until you can swap out pucks in your fixture. Reading the forums is a must and keeping your cool is essential! Hang in there and I'm sure we can all benefit from your experiences as well as you from some of ours.

[jonnybravo22]

Originally Posted by reefsurfing

Is that a TV mounting bracket?

Sort of. I got it from a company that allows you to customize mounts for TVs, GPS systems, etc.

http://www.ram-mount.com/

you can mix and match pieces.

[CalmSeasQuest]

Originally Posted by jsousa

Tom,

Agree with all your points. LED is the obvious way to go. Too many pluses.

Anyway, do you have any pics of you tanks? I'm actually interested in how you mounting the AIs. I need to do it with aesthetics in mind. I was actually go to build a mount for them as opposed to hanging from the ceiling or ruining the rimless look of my new Reef Savvy 50 gallon. Any pics from anyone would be greatly appreciated.

There are multiple pics of my setup in my album and in the early pages of this thread. When I first received my AI's, the hanging kit was not yet available so I used the feet on the rails which placed them just inches above the tank. This was a disaster as it resulted in too much par in the area directly below the lights, and did not provide adequate spread throughout the tank.

Once the hanging kit was installed, I played around with numerous heights, and settled on 16" above the water's surface. This provides more then enough PAR and prefect coverage.

That height would change with new AIs as they just made a change to the optics. (I posted this in a LED Coloration Thread, but it seems relevant here...) In speaking with Chris at MACNA, he explained they now ship with 70 degree optics on the front and back of each unit (4 pucks.)

My other observation was regarding the color of the SOL blue pucks (W/B/RB) - I have AI's (DT) running beside a Maxpsect G2-160 (FT.) The G2 uses SemiLED Royal Blue LEDs and IMO, has an unpleasant "fuzzy" purple color...


In this photo, the G2 (on the right) is running all of it's SemiLED Royal Blue and violet LEDS at full power (14 Blue + 4 Violet = 18 LEDS @ ~3watts = 54 Watts.) The Violet LEDs put out so very little visible light, they do not influence the color. The AIs are running only their Cree blues and at 25% power (16 @ ~3 watts = 48 Watts X 25% = 12 Watts) At these settings, both are generating the same 190 PAR measured 6" directly below the center of each lights (note - the results were the same with second AI unit turned off so no light bled into the test.) The impact of the optics on the AIs is apparent.

I was pleased to see that when combined with the Cree Blues in the new AI tri-color arrangement, the Royal Blues are not as purple in appearance. To my eye, the visible color change was pleasing, especially at higher power settings. For reference, at 100%, I'd estimate the W/W/B to appear about 10K~12K in color whereas the W/B/RB look to be about ~20K. My only reservation is you lose quite a bit of "pop" without the extra white LEDs. Even at 100% settings, the display tank did not look as "bright" as the W/W/B version. This is of little concern to me as I've never run the whites higher than 50% power. I'll just dial back the blues a bit to obtain a ~14K look.

Unfortunately, AI's display tank didn't contain any fluorescing corals to demonstrate the extra actinic power of the SOL blues, but based on what I saw, I believe it to be a good update.

I have a standing order to upgrade my W/W/B pucks with the new SOl Blues when they are available (I'm keeping my 40 degree optics.) My initial intent was to intermix the pucks, but as this upgrade also requires a new system board, that won't be possible. I will upgrade one unit then photograph and take PAR measurements comparing the two units running side-by-side prior to updating the other.

[CalmSeasQuest]

FWIW, I continue to reduce power settings on my AI's. I've been slowly stepping down from 50%W/100%B and am presently at 40%W/95%B.

It's still early BUT, I think I'm beginning to see improvements in coloration. I've loaned out my PAR meter, but will have it back next week to get some baseline measurements. It's *possible* that even at the reduced settings I've been running (max 50%W/100%B), it was still too much light.

Time will tell.

[XSiVE]

Originally Posted by CalmSeasQuest

FWIW, I continue to reduce power settings on my AI's. I've been slowly stepping down from 50%W/100%B and am presently at 40%W/95%B.

It's still early BUT, I think I'm beginning to see improvements in coloration. I've loaned out my PAR meter, but will have it back next week to get some baseline measurements. It's *possible* that even at the reduced settings I've been running (max 50%W/100%B), it was still too much light.

Time will tell.

Tom, I think you are seeing exactly what I am seeing too... At first some of my corals lost a lot of color but I've since turned my lights back down to about 70-80% total and things are really starting to color back up. My GARF bonsai for example is getting some really dark purple coloration now that Ive dropped the intensity, my 20K Lokani is starting to show proper coloration as well.

I'll give you a call and get the PAR meter back to you this weekend if you're available, if not We'll figure something out.

[reefsurfing]

Tom-

Thanks for all the info on the new AI units. As soon as I heard about the 70* optics front and back I placed my order for the new Sol Blue 24" kit. I like that AI is addressing these issues as they come up and it really speaks volumes that AI is more of a 10 year invesment than "just another cool light". I am looki ng forward to seeing your new setup with those measurements from the sol blue unit.

[BriGuy31+]

Thanks for all the info Tom!!

[larryfl1]

i took delivery of my sol blue the week they were released...

would mine have the 70 degree optics? whats involved in changing if mine do not?

[CalmSeasQuest]

Originally Posted by larryfl1

i took delivery of my sol blue the week they were released...

would mine have the 70 degree optics? whats involved in changing if mine do not?

I'm not sure when AI changed the perimeter optics to 70 degrees, my "impression" was that is was very recent. Give AI a call, they can quickly determine what you've got.

For my use, I see no benefit in the 70 degree optics as I have my lights hung about 16" above the water surface. The increased light spread would result in more light being "washed" out of the tank. Conversely, for those that are using the legs and mounting on top, the increased spread would be very useful.

[BriGuy31+]

How can I get a hold of different optics for the tri-pucks? I have the 70s and would like to experiment with different optics.

[CalmSeasQuest]

Originally Posted by BriGuy31+

How can I get a hold of different optics for the tri-pucks? I have the 70s and would like to experiment with different optics.

I haven't seen any info on optic options (other than what Chris shared about the 70s at MACNA.) I do know that the lenses are separate from the pucks, so in "theory" you should be able to swap them out. I'd give AI a call, or maybe better yet, make the inquiry via a trouble ticket. They respond very quickly.

Let us know what you find out - others will likely be interested as well

[90ct]

I got the same problem with my AI. I set the white to 55% from 60%, Blue at 95% 'cause most of my SPSs from middle to top bleach out. I got 180g (72x24x24) and used only 5 modules instead of 6, supplement with 2x84w T5 Blue+. The AI is about 10" above water surface. T5s turn on from 11:30am-9:00pm, LED turn on at 12:00pm-6:00pm (1/2 to full power increasement/off). So far the SPSs color still not so intense, at least it's not brown out :-). Any advice on setting my lights (time, power.....)?

[jonnybravo22]

Just got PAR meter and took measurements. Interesting. I'll get a photo editor and try to label the pics with PAR numbers

[CalmSeasQuest]

Originally Posted by 90ct

I got the same problem with my AI. I set the white to 55% from 60%, Blue at 95% 'cause most of my SPSs from middle to top bleach out. I got 180g (72x24x24) and used only 5 modules instead of 6, supplement with 2x84w T5 Blue+. The AI is about 10" above water surface. T5s turn on from 11:30am-9:00pm, LED turn on at 12:00pm-6:00pm (1/2 to full power increasement/off). So far the SPSs color still not so intense, at least it's not brown out :-). Any advice on setting my lights (time, power.....)?

I don't have access to my PAR data at the moment but for reference, here are some measurements from earlier in this thread. One caveat, I had just received the PAR meter and my methodology was still developing. As the readings vary greatly with the slightest movement, I'd use these +-~10%.

6" - (Air) - 100%=1650
7" - (Air) - 44%W/100%B=1425
12" (water surface) - 100%=1370 / 100%B/75%W=1105
16" (4" water depth) - 100%=915
19" (7" water depth) - 100%=690
24" (12" water depth)-100%=560

Lots of variables, With multiple units, depending on the height and distance apart, you can expect a significant increase from overlap. You have to factor in acclimation (what type of lighting were the corals under prior to your AI's?), the lighting duration plus the output of your T5s.

Interpolating this, with your settings at 60%W/95%B, my "best guess" would be you were blasting your top SPS with ~1000+ PAR and remember... according to Sanjay, PAR meters underestimate our very blue light by ~15%. The other thing to note is the small loss of PAR at depth. The 40 degree optics do a great job of delivering light deeper in the tank.

I'd reduce to 35%W/90%B and very slowly increase over weeks.

LED output will "appear" much dimmer than comparable wattage MH/T5 setups, while delivering far more PAR. I made this same mistake TWICE, now I am a believer. Go very slow and (once they recover from being cooked) your colors will steadily improve.

I'm traveling for the next few days, but if you like I'll duplicate and measure your 60W/95B with overlap setup next week (how far apart are you AI's?)

[jonnybravo22]

OP hope you dont mind me posting my data. As you indicated my measurements were also pretty variable with any movement at all, but i kept water movement as it is normally to see what the corals would get in reality.

I did see very high PAR under 100% scenarios. In the last week or so I have turned down the intensity to 40% W 60% B and reduced my light cycle. I have seen some improvement in color in the last week so I'm going to continue with the lowering and monitoring.

[patriotsreef]

Ok, Ive been reading all about the AI fixture and all of the GREAT things. Im one of the poor guys that bought a solaris 2-3 weeks before they disappeared from the planet. My tank is 48X48X36 and Im running the solaris 16" above the water line with a MH fixture 2x150 and 2x70 in the front also 16" above the water line. I'm very interested to hear the actual company info, is the patent info rock solid etc... I don't mind spending the money on the fixture but need to feel better about the company. I thought the Solaris was the wave of the future so I wanted to give it a try. I knew going in that there would always be new releases coming out and that mine would be out of date soon but I didn't expect the company to disappear.

All of that said, id like to know thoughts on this deep tank and what I would need to properly light it. I've got a huge rock structure so many of my corals are 12-16" below the water line and many are near the bottom.

[datagr1ff1n]

Originally Posted by patriotsreef

Ok, Ive been reading all about the AI fixture and all of the GREAT things. Im one of the poor guys that bought a solaris 2-3 weeks before they disappeared from the planet. My tank is 48X48X36 and Im running the solaris 16" above the water line with a MH fixture 2x150 and 2x70 in the front also 16" above the water line. I'm very interested to hear the actual company info, is the patent info rock solid etc... I don't mind spending the money on the fixture but need to feel better about the company. I thought the Solaris was the wave of the future so I wanted to give it a try. I knew going in that there would always be new releases coming out and that mine would be out of date soon but I didn't expect the company to disappear.

All of that said, id like to know thoughts on this deep tank and what I would need to properly light it. I've got a huge rock structure so many of my corals are 12-16" below the water line and many are near the bottom.

I have the new Sol Blue fixtures, x4. I can tell you that I do not know anyone that is running the lights at 100% power. They are so powerful that with my 29" deep tank they nuked my inverts. I have the lights at 30% power now. As for the company, they are wonderful. FAST and I mean FAST response via support ticket. Licensed under the company that sued and shut down PFO so no problems there. I would say call up AI and talk to them to see what you need as far as your setup. But the PAR is insane on the lights, when it comes to par I know they will get the job done. Really though I went with AI because I do not want to deal with CHINA to get a problem fixed. They are in the USA and following all the right laws on patents.

Long story short they are wonderful.

[CalmSeasQuest]

Originally Posted by datagr1ff1n

I have the new Sol Blue fixtures, x4. I can tell you that I do not know anyone that is running the lights at 100% power. They are so powerful that with my 29" deep tank they nuked my inverts. I have the lights at 30% power now. As for the company, they are wonderful. FAST and I mean FAST response via support ticket. Licensed under the company that sued and shut down PFO so no problems there. I would say call up AI and talk to them to see what you need as far as your setup. But the PAR is insane on the lights, when it comes to par I know they will get the job done. Really though I went with AI because I do not want to deal with CHINA to get a problem fixed. They are in the USA and following all the right laws on patents.

Long story short they are wonderful.

I agree with all said. AI is the ONLY licensee under the Orbitec patent, so whether you agree with the broad reach of those patents or not (which I do not), AI will not have Solaris type problems.

I had an opportunity to test AquaIlluminations customer service directly, and can attest they are wonderful. Excerpted from earlier in this thread...

"About 6 weeks ago, I was adjusting the AI's which are hung above my tank when I did something stupid. While attempting to raise the lights (did I mention they are PAR MONSTERS?) my hand slipped and raised the right end of the rails too high, causing one of the AIs to slide off the other end and fall directly into the tank...The light was dead and it was entirely my fault.

I contacted AI (on a Sunday), Chris said to send it in and they would take a look at it ASAP. It was overnighted on Monday, they received it on Tuesday, repaired it AND overnighted it back to me THE SAME DAY. I had fried the main system board. AquaIllumination had it repaired within hours of receiving it and because of their efforts, I was without the light for less 72 hours. The cost?...Absolutely nothing."

Your tank's dimensions are tough to light, especially without seeing the coral placement and aquaculture. In order gain enough coverage using one row of AIs, you'd have to raise the lights so high, I'd be concerned about having enough PAR at 36" of depth. I would contact Greg at ReefGeek or call AI directly to get their opinion. My "best guess" would be 6 units total (3 each on 2 - 4' rails) mounted ~16" above the waterline. Depending on your coral placement, you *might* be able to get away with 5 units (especially with the new 70 degree perimeter optics.) You can always start with 5 and simply add more if needed.

This would provide plenty of PAR and should give you sufficient coverage using less than ~340 watts.