Lights for 48" tank

nstd · Jan 25, 2017

I have two kessil 150 and two 36" t5 bulbs. Will that be enough? I have mainly sps.

Should add another led fixture? I was thinking of adding 1 mars aqua in the center and then kessils on the sides.

Or should i add two more t5 bulbs plus my 2 kessils?

pdt7361 · Jan 25, 2017

What are your tank dimensions other than 48" long?

nstd · Jan 25, 2017

pdt7361 said:
What are your tank dimensions other than 48" long?

18 width and 20 deep

CMD2213 · Jan 25, 2017

The kessil are fine I think the t5 would be more benificial.

mcarroll · Jan 26, 2017

Why not complete the Kessil installation vs going the other direction?

If cost is the answer, then why not sell the Kessils and go all-T5 or all Mars, for example?

If you really prefer the all-over light from the T5's, then why aren't you considering LED's that are more like them (I.e. Orbit Marine Pro or IC, GHL Lightbar2, etc.) instead of using spotlights like you have now?

(P.S. I suspect you're fine as-is.....but you need to be using a light meter to assess your system vs "crowd-sourced guessing" like this. A lux meter like the "LX-1010B" I use is around $15, delivered so it's really a no-brainer. You want to have 10,000-30,000 lux at the surface...roughly speaking. More is OK, but definitely not "better".)

nstd · Jan 26, 2017

mcarroll said:
Why not complete the Kessil installation vs going the other direction?

If cost is the answer, then why not sell the Kessils and go all-T5 or all Mars, for example?

If you really prefer the all-over light from the T5's, then why aren't you considering LED's that are more like them (I.e. Orbit Marine Pro or IC, GHL Lightbar2, etc.) instead of using spotlights like you have now?

(P.S. I suspect you're fine as-is.....but you need to be using a light meter to assess your system vs "crowd-sourced guessing" like this. A lux meter like the "LX-1010B" I use is around $15, delivered so it's really a no-brainer. You want to have 10,000-30,000 lux at the surface...roughly speaking. More is OK, but definitely not "better".)

Thanks for the responses. I didnt you can do that with a lux i thought reefers only use par meters.

mcarroll · Jan 26, 2017

A lot of people think the same....it took me roasting a tank full of SPS when I switched to LED's to teach me the lesson. Well, that and some reading. ;)

It's true that PAR is a more accurate assessment of light (still inaccurate), but our use-case really doesn't typically demand anything more than a lux meter can do.

Consider that there are some known conversion factors of different lights...with a known conversion factor, any lux reading you take can be simply converted to PAR mathematically. You can create a conversion factor for your lights if you can borrow or rent a PAR meter from someone (friend, reef club, etc) and measure with the PAR meter and the lux meter. The conversion factor is the ratio of lux to PAR.

The sun makes a good example.....about 100,000 lux with a lux meter, and about 2000 PAR with a PAR meter. 100,000 ÷ 2,000 = 50 The sun's conversion factor would be about 50.

Using the same logic and some practice, it's not too hard to predict a conversion factor for most lights even if there's no existing conversion factor.

But in everyday reality, most of us using lux meters don't convert to PAR....ever. The only time I do is when communicating online with someone who's only "fluent" in PAR or who's actually using a PAR meter. When I do use a conversion factor, almost 100% of the time I just use 50 because it is easy to remember and do the math in my head....remember that you're dealing with general, imprecise numbers by the nature of what you're measuring and it works fine. For example, 23,327 lux is always going to be "around 20,000-30,000 lux" when actually making use of the number. (Does that make sense?)

And after you place the order for your lux meter, while you wait on shipping, you can download a lux meter app to play with on your smartphone. Not all apps seem to be 100% compatible with all cameras, so make sure you get good reading on a known source (like the sun) before you decide you have a good app.

jd371 · Jan 26, 2017

Same dimensions, I'm running 4 Kessil 150's with 2 t5 as supplements. I have them about 8" from the surface on a 12 hr (LED) and 6hr (t5) schedule.

Two weeks ago I redid the lighting to clean it up of all the wires. I installed PVC to mount and hide the wires.

mcarroll · Jan 26, 2017

jd371 said:
Same dimensions, I'm running 4 Kessil 150's with 2 t5 as supplements. I have them about 8" from the surface on a 12 hr (LED) and 6hr (t5) schedule.

Did you ever try them at about 4-5"? How was it?

Here is what I was thinking for @nstd, so we'd appreciate any feedback from your experience!! :)

(I know you expressed no questions or complaints. Yes, it's fair to say I think too much. This is your only warning. :D)

8" gives you a diameter of coverage under each fixture of about 44" at the water surface! :)
And I know it's only a recommendation, but Kessil does say "up to 24 inches of coverage" with the A150.
They also say three or at most four A150's should support a "standard" mixed reef. The Kessil Calculator too.
(I admit I don't understand their mounting height recommendations on this tab....the rest of their advice and calculator is coherent with the math/theory.)
So theoretically, 8" is pretty high for Kessils. Twice as high as you'd want for "up to 24 inches of coverage".

You might have good reasons for doing 8" anyway, but just to say so: Mounting them that high actually wastes quite a bit of the light your A150's generate! How much?

A 44" projection would cover 1,520 square inches of surface area.
If you cast 1,520 square inches as evenly as possible over your 48x18" tank...
...something like this...
...you'll waste 656 square inches of coverage in front and in back of the tank.
That's over 40% of your total coverage wasted.
That effectively makes your 34 watt A150 act as a 20 watt...about on par with an A80.

Lowering them to four inches would theoretically double the light intensity at the water surface and still give you a 22" diameter of coverage – plenty.

You could run the four you have in a row instead of the grid format.
There would appear to be fewer shadows
The shadows present would appear to be dimmer
The tank would be brighter from the fixtures being closer to the water
...and from having more overlap between them in the tank
...and from spilling 100% less photons outside the tank into the room. :)
I would experiment with eliminating the T5's with this configuration too.

If the 8" mounting height is not up for debate, did you ever consider more Kessils (1 or 2) vs the added T5's? It kinda works out the same in the tank as my example above at 4". Of course up-front costs are more considerable than T5's. ;)