How high up should my light be?

[JF121]

I'm a complete newbie trying to do it right the first time. I have a 90cm 40watt mariglo light over a 160L rectangular tank and I'm wondering how high it should be to roughly optimise par levels. I have live rock that is relatively close to the ground spanning from one side to the other.

Any general advice would be useful as i carelessly attached the hinge and light before filling the tank and putting it against the wall. My light is currently about 10cm above the water which seems very low for such a large light compared to ones I have seen from experienced reefers.

Thank you for your time if you read this far,
Jake

 

[blaxsun]

Most lights are between 8-10" from the water surface.

 

[1ocean]

I visited WWC in Florida and they had tanks where the lights were "feet" from the tank. Reason I learned was they were after more spread and less shadows. Also to balance the loss in par you can increase light out put if needed, or you could use the height to lower par if needed...
I keep my four Radion Gen 5 xr30 at 16" from the tank top. Mostly have LPS zoa's and a few SPS...

 

[PatW]

It depends on the light. The new Radions have improved lenses which gives better spread at a lower level. Aquaillumination lights require a higher position, With LED lights you get better result with multiple fixtures spread apart. It gets a bit complex. Most people just set lights about 10” from the surface. But the higher the light and the more fixtures the better but you need more wattage with greater height.

 

[dedragon]

I dont know much about that light as they arent us based but they seem very similar to the nicrew lights or current usa orbit with their layout and power.
They list the 40w as a replacement for a 6x 39w t5 replacement but there is no way that is actually true. I am going to guess that this light will not perform as you are expecting and to look into a better light as this will not give you nearly enough par regardless of mounting distance. It will be fine for growing soft corals if mounted using the mounting legs

This is the light i think?

https://aquaone.com.au/prodinfo-aquaone/MariGlo.pdf

 

[dedragon]

In australia Illumagic is a well known brand, i think pacific sun and ghl are also easier to get over there that are european brands, Orphek, ecotech, ai, and kessil i think all ship there as well

 

[JF121]

I have looked into par meters and decided it's out of my budget, i've instead done research into how par affects the organisms and am currently photographing the live rock bacteria to see where it grows the best. I will begin with a cheap coral taking note of it's suggested par levels and very gradually see where things work over time. I think this approach can patch up some of the science stuff and lead to successful coral.

Thank you for all the messages.

 

[dedragon]

I have looked into par meters and decided it's out of my budget, i've instead done research into how par affects the organisms and am currently photographing the live rock bacteria to see where it grows the best. I will begin with a cheap coral taking note of it's suggested par levels and very gradually see where things work over time. I think this approach can patch up some of the science stuff and lead to successful coral.

Thank you for all the messages.

Definitely research is going to be your best friend but IMO those lights dont really belong on a reef tank, they will not have the power to support much more than soft corals if that. They are more made as fish only with live rock tanks (fowlr). Best bet for cheap would be to return it and get 2 orhek or3 (or similar), or 2 smat farms leds as they should run around the same price.
The lights you currently have will be lucky to put out 100 par at 6". Sorry to be blunt but i see many beginners start off using similar lights and they usually never work. Only for soft coral tanks that are extremely shallow like a fluval 13.5

 

[dedragon]

Unless mounted very high the corals will suffer and you will have very low growth at the bottom of the tank. What is the height of the aquarium itself?

OR3 Reef Aquarium LED Bar •Orphek

Orphek OR3 Reef Aquarium LED Bar, OR3 60 / 90 / 120 / 150 for Coral Pop Fluorescent Color Growth and Illumination – 5Watt Dual Chip LEDs

orphek.com

Amazon product

 

[Koh23]

Or you can try free par meter app, caled photone, there is topic, so, take a look

 

[redfishbluefish]

The general rule on LED's is 12 - 14 inches (30-36cm) above the waterline, but that could change dependent on lenses, or lack thereof.

As stated, that light is relatively weak and you'd be lucky to grow softies. Appears to have low wattage LEDs that would have poor penetration. Higher power lights can be found that are not overly expensive. These are commonly referred to as "black boxes", and typically made in China. Here in the states, a 165W fixture with 3 watt LEDs can be had for around $100 US.