JBJ 28G Nano Hanging Led Fixture

[neoburn1035]

Hello everyone I am new to the Nano-Reef forums, but I have been very active on my local forums. Not many people have done diy led retros or fixtures on my local forum, so I came here because I have a few questions before I start to build my fixture, and it looks like there is alot of experience here in LED DIY from the posts I have read. I do apologize ahead off time for the length of this post. I am a noob when it comes to DIY led's. I am just getting back in to reefing after a 5 year break. So here I go.

 

(Its like pop quiz in school) So lets begin, you have 45 minutes, you may start now." just kidding Thanks in advance for the info.

 

First let me start by telling you all what I have already. I purchases from a local reefer a 12 Ultra Premium LED DIY Kit with Dimmable Driver link to the kit. The driver is a Mean Well ELN-60-48D dimmable driver and he ordered the 65 degree lenses with it, two extra led's of each color and an extra Mean Well ELN-60-48D, a 6 x 9 heatsink tapped for 18 led's at 1.75in center to center on the led, two pots, two 10v ac adapters, thermal grease and screws to mount the led's.

 

Let me tell you what I am looking to build and what I was looking to keep keep in my Nano.

 

The fixture will be hanging over my JBJ 28G Nano. I am looking to hang it maybe 8-12" off the top of the water. I am also looking for as close to a MH150 10k bulb as I can get.

 

I am wanting to keep some pretty hardy corals and maybe one ore two more difficult speciems as the tank ages. Some of what I am looking to keep are maybe like a frogspawn or two in different colors, some zoos, a hammer coral, a sabae, a sps or two in the future. I am not sure what else at this time but that should cover it for now.

 

 

So now to the questions I have.

1) How many led should I have to get good coverage? Would 28 be enough? That leads me into the next question.

 

2) If looking at 28 led's, the drivers say they can run ~8-14 led's. Could I run 14 led's reliably on one driver or should I get a third and break it up more. Maybe save some wear and tear on the drivers and led's? Won't really matter if I need more than 28 led's anyway.

 

3) If I looking to match a MH bulb should I stay with the RBs and the CWs only? Or should I add in some neutrals and some blues?

 

4) What ratios should I be looking for 1:1 or 2:1 RBs:CWs or other ratio. to get the Par of a MH.

 

5) What spacing am I looking at to get good coverage over the tank?

 

6) I assume also that the one heatsink is not enough for the amount of led's I am going to need to run would another 6x9 heatsink be enough? When I cut it out of card board it looks like it would cover the tank pretty well.

 

7) To get the par of a MH or maybe better should I used lenses? If so it looks like every one is using the 65 degree ones. Is that the best option? Could you also do a 50/50 mix of lensed and no lensed led's and get a good overall par rating through out the tank?

 

8) Is 8-12" off the top of the water a height to start with or should I start closer or farther away?

 

Ok I think that's all the questions I have for now. I am sure the answers I get from this post will give me a few more things I am not thinking about here.

 

Thanks for reading.

Neoburn1035

[evilc66]

1. With you hanging the array over the tank, you should be fine with what you have. 24 LEDs is pretty common for hood retros for this tank, but that's because the LEDs are much closer to the water, and need more to cover a larger area.

 

2. You can only safely run 14 LEDs on that driver if they are XP-G's or similar low voltage LEDs. XR-Es and XP-Es should be limited to 13.

 

3. It will work fine with cool white and royal blue. Neutral white just helps with some color rendering, as does cool blue.

 

4. Doesn't matter.

 

5. If you are going to use the heatsink you have, your spacing is already set for you. 1.75" on center isn't bad.

 

6. That heatsink will be fine, but it should be fan cooled. The size is fine, as you will be mounting the setup higher than most would on this tank.

 

7. Depends on how high you end up mounting it. Up to 6" off the water, you shouldn't need lenses. Any higher than that, and it would be a good idea so PAR levels are kept in a suitable range. You want to use lenses on all or nothing. Mixing them will only create hotspots in the tank.

 

8. That's up to you, but it's a usable distance. The further away, the more you will need lenses to raise the PAR levels up.

[neoburn1035]

Thanks evil. Is there anything else that I should be taking into consideration? If i understand you correctly on the heatsink I only need the one 6x9 or should i get a second one. I can only fit 18 leds on the one I have now with a 1.75 on center spacing.

 

I have fans also I forgot to mention but no power supply for them I was looking at running 2 fans will that be enough? What type of power supply would I need?

[evilc66]

You should only need a single fan. Any 12v power supply that has enough current to run the fan will work. You could even parallel it off one of the 10v power supplies used for dimming (before the adjustment pot).

[neoburn1035]

Ok so I have finally ready to start my build. I have changed the drivers to the p drivers now and also got the rapid led controller. I also changed my heat sink to a heat sink from heatsinkusa. I went with a 8.460" x 8" sink. Below is the layout I was thinking of using. I just wanted to get an opinion if it was good or not. I am also going to use 65 degree lenses on the cool whites and 55 degree lenses on the royal blues and hang the fixture about 8" above the water.