LED Sanity Check

[mneville277]

I am currently running 2 Current Orbits and have gotten decent growth, but am limited in what SPS I can sustain with those. So, I'm considering jumping into the realm of a DIY LED fixture and wanted a sanity check of the plan before I lay out the money and make a mistake.

Going around 18" over my 36x14x12 25g AIO DIY home-brew frag/grow-out tank (30g total system) housing LPS, SPS, softies, and one happy little 6-line wrasse:

16 Cree XT Royal Blue, 12 XP Cool White or 14 XT Cool White, 4 UV, 2 Ocean Coral White, 2 MW ELN-60-48D (RB and W) and 1 ELN-60-27D (UVs and OCWs, turned down to 500mA).

The plan was to split between two 12" fixtures wired series/parallel adjusting the drivers to output no more than their rated 1300mA between the two fixtures. Or would it be better to wire all in series and have a jumper between the two? The drivers and lights are all within limits either way in case of a malfunction.

Ramping/dimming would be handled by the RKL.

Is 34-36 LEDs overkill for this project? Seemed like a lot in comparison to what I have noticed others getting away with on similar sized tanks (20L and 29g). Series/parallel good here or better to daisy chain the fixtures in series? (Makes no difference to me - was just doing series/parallel for symmetry and aesthetics).

Does this all sound right to anyone?

 

[perkint]

It does seem like a lot of LEDs, but what's the problem with that Run them a bit lower if you want and get more light per watt and less heat! And you can always turn them up if you want more light!

I'd go series across the lot. Saves issues with different brightness/current draws due to variations of fV across the LEDs. You can sort this out by swapping LEDs round until you have balanced strings for running in parallel, but I don't see the point personally!

Tim

 

[Webmanny]

It seems to me that you are right on the mark. In fact, in order for you to get the most out of your LEDs and extend their life, you could go with even more LEDs.

For example. My tank is a 36 gallon tank and I have 48x3W LED, which translates to 144 watts at 100% capacity or 4 watts per gallon. However, I run this light at 70% to 80% and for the types of corals that I have, this is fine, but I have not been able to keep some of the more demanding SPS corals due to this limitation.

By comparison, your tank in running about 108 Watts, which is 4.08 watts per gallon at 100% capacity. For most entry level SPS corals this should be ok, but for the higher demand SPS corals, 5 to 9 watts per gallon is the recommended level. Also, at 18" above the tank, you may want to go with more.

Please note that I am by no means an expert and this is solely my opinion and experience.

 

[mussel and hate]

I'm probably the wrong guy to check your sanity. I'm running 58 LEDs on a 12" Maker's HS. 2 Parallel strings on a 450mA driver. So ya, 58 stars at ~225mA over a 20 gallon.

I've lowered them gradually to about 2.5" above the waterline. Any lower and I lose a lot of coverage. I will probably experiment with drive current next.

There is no evident disco or color banding with such high density. Everything runs cool and a single 40w driver(maxed out) powers the whole shebang.

It's likely crazy, though no more crazy than anything else in this hobby. I say go for it.

 

[perkint]

Driving lots of LEDs at low current has lots of advantages and not many disadvantages (initial cost and possible colour shift due to low drive - one obvious and the other easy to balance) so that side of it is always good IMO

Tim

 

[zachts]

Doesn't sound too crazy to me (working on 128 LED build to put over my 55 gallon, LOL)

I would avoid using Cool White though, pretty lousy color rendering. I'd go with neutral whites at least, and preferably something in the 4000-5000k range that sports a 90+ CRI rating (like the nichia chips for single stars), but that's just me.

OCW are nice but only to balance out the crappy color of CW. with a high CRI white you don't need them, I'd add a lot more violets in the 420nm or 430nm range instead. along with 6 or so standard Blues spread out in your Royal Blue string.

Three drivers, blue string (only going to get 14 on one driver though), white string, violet string so you can adjust the overall look. Overall more whites than you need, 2:1 blues to whites (that's still a lot of white for most people's preference), don't count the violets in that ratio.

 

[mneville277]

I appreciate your feedback. Made some changes and pulled the trigger - 10 neutral whites, 20 royal blue, 6 UV, 2 OCW; 3 ELN-60-48D (running at 700mA); and I found a sweet little 24x6x3/4" heatsink, so all wired in series.

Figured with everyone's input, this should be a good place to start. I can always modify as I go - pretty much the point of going DIY, right?