Finnex PAR - Am I reading it right?

[lullafishi]

Hey guys!

This may be an easy or obvious question, but I just want to make sure before I pull the trigger.

I'm interested in getting a Fugeray for my first 40b set-up, and I cannot figure out if the "depth" in the Finnex PAR chart is from top/light to bottom/substrate, or if it's the depth of the tank as in front-to-back dimension?

If my tank's dimensions are 36" x 18" x 16" tall, with 2" legs on the light and about 2" of substrate, what will the PAR be for a 36" fugeray?

Is it high 50 PAR or mid-high 40 PAR?

I want low-medium light with no C02 and occasional ferts. Will this be too high light, and if so, will using a glass top or screen mesh help bring it to a level where I won't have problems without C02? I'm not interested in suspending the light at this time.

Thanks!

[nvladik]

It's high 50... the vertical marks on the chart are height, specifically form the LED's themselves to the substrate.

[lullafishi]

Thanks for clarifying that, nvladik!

Can anyone offer advice about adding mesh screens (what type and how many layers) or a glass top to help bring the PAR down to a more low-medium light for no C02? Or should I start a new thread about this in Lighting?

[nvladik]

If you can hang the light, I would get a smaller light (like 24") and hang it 6-12" above the tank.

[lullafishi]

Thanks for the suggestion, but I'm not too keen on suspending a light for this set-up. The tank will be near the tv in our living room and I'm trying to avoid too much light spillage. I also can't find a method of suspending something in an aesthetic manner... wish I could drill into the ceiling but our place is a rental so that's off-limits right now.

I could potentially use a shelving unit to support the suspension, but again, I'd like to avoid a lot of light spillage.

[jbrady33]

From what I have read one layer of regular cheap fiberglass screen from Home Depot or Lowes would reduce light about 40% if I remember correctly. I think Hoppy had a thread where he actually measured this with a par meter, you could search for that.

If it were me I would take the 2 screws out that hold the endcap of the light on, the polycarb lens/shield on the light just slides out of the end. Cut the screen a bit smaller than the shield, slide the shield & screen back into the fixture. Your top can still be open or glass without seeing the screen, but it is in the light to cut down PAR.

[lullafishi]

I'll see if I can find the thread you're recommending.

The inserted screen sounds like a great fix for me! Promise it'll be child's play? I've seen how adept you are with modding these fixtures, haha! But really, it sounds like I could handle that, thank you!

[flipanda]

Originally Posted by nvladik

It's high 50... the vertical marks on the chart are height, specifically form the LED's themselves to the substrate.

if the vertical marks is the distance, what are the horizontal marks for?

[blink]

Distance to the side from the axis of the light.

[Ach1Ll3sH33L]

keep in mind those par readings are taken in open tanks, with no water. So they dont account for water surface reflection etc. you will have less par than what is shown in the chart, so you may find you dont need to reduce the lighting