New Lux Meter to check lighting for a mixed reef aquarium

[saltyfilmfolks]

Could you explain the lex@1:1 ratio at 50?

I have a pacific sun led,t5.... if the lux meter reads 50,000 how does that convert to par at the surface and at the bottom of a 125g tank? I just want to make sure I'm following all of this.... thanks.

Sorry. Most Led run in a blue white ratio. so both at full intensity.

On a pac sun MH t5, you shouldn't really worry about imo. thats great light w plenty of PUR too. But the info could be useful. And if you see intensity dromp over time in lux it could help trouble shoot.
If your running a 14k mh and and 2 blue t5 id do the math at 45 to average. Keep in mind your making an estimate

If I had your light based on those colors Id run 40, 45 and 50 to get the range.

50,000/40= 1250
50,000 / 45 =1100
50,000/50= 1000

Additionally id meter the led separately as well as Id doubt it contributes significantly to both Intensity and Par. ie 1000 lux moonlight/60(for led,) = 16 par

 

[mcarroll]

I agree.....I would simply divide by 50 (because it's easy to do in my head) and think of it as "around 1000 PAR". There really isn't a need for more accuracy than this.

They say intensity drops by about 1:2 in air....or if you double the distance from the light source, you halve the amount of intensity.

I think it's close to 1:4 drop in water, but that's a less precise estimate than in air as water and its constituents have a much more pronounced effect on light. I think it's still close enough for our purposes....and I think if you look at some PAR maps (if you can find some with enough detail) you'll see this 1:4 trend.

I never bother with this level of figuring though.....but if you were (for example) to bring a large coral home from another established system, you might want to find a spot in the tank that was likely to have the same light, so maybe it would be worth it then.

Myself, I would either ask them to measure the light directly over the coral (sensor should cast a heavy shadow on the coral/spot in question) or take my meter and measure it myself. Then with the meter over my tank, in a spot of similar intensity, I can see where the shadow falls and have a great idea where to start with placement.

Make sense? Harder to explain than to do. Getting a lux meter and just using it for the tank and other things will answer a lot of questions. It's a complicated subject, yet not nearly so mysterious as it sometime seems to be.

 

[saltyfilmfolks]

you might want to find a spot in the tank that was likely to have the same light,

acclimation is key.

 

[Syntax1235]

Just for clarification.... the Pacific Sun fixture is LED/T5.

Thanks for all the good information.

I guess when I get readings I can post them here for comments?

 

[saltyfilmfolks]

Just for clarification.... the Pacific Sun fixture is LED/T5.

Thanks for all the good information.

I guess when I get readings I can post them here for comments?

gotch, Meter both individually, to see the intensity ratio then average at a higher conversion number as we did with Mh t5.

 

[sdavi66572]

@sdavi66572 BTW, do your lights come with 90º or 60º lenses?

With 90º lenses you should be able to get away with that 12" mounting height you have....maybe just a little higher, but light spill may get significant quickly. I suspect you have 90º lenses, but you should confirm if you don't know for sure.

If you have 60º lenses, then you would have room to go up to 20" off the tank.

With 120º lenses, 6 or 7" would be more favorable, but I would wonder how much light you'd be getting to the bottom of the tank.

The lux meter in a ziplock bag would answer that!

Even with 90º lenses, I'd be a little curious just what the bottom is getting.

Just to use a well-known, published comparison: The Orbit Marine Pro puts a comparable amount of light at the water surface as your current setup, but even with 60º lenses only gets around 2500 lux to the bottom at 30".

So it's worth measuring at least once.

It's also worth noting that those fixtures are cheap enough that you could opt for a closer mounting height AND to run two sets of them, one in front, one in back. You would be able to run them all at about 1/2 power, but coverage would be around 100% with very little fall-off from front to back.

Last point: Unless your rocks reach all the way to the top of the water, your corals aren't going to be subjected to all that much intensity. Yes, the surface is brightly lit. But the bottom is probably mesophotic – borderline for photosynthesis. That doesn't mean corals won't grow there, but it means that they could be pretty dependent on dissolved nutrients as well as particlate nutrient sources even for carbon.

My lenses are a combination of 90 and 120. I went a head and bump my lights back up to 62000 lux at the surface of water. I have not tried to use a zip lock bag to check at different levels. I will try and check tomorrow. Still in the process of getting my phosphates down, currently at .07. Im going to post some photos.

 

[mcarroll]

.07 ought to be pretty good. You definitely want relatively higher nutrient levels to support the higher light levels. If PO4 becomes limited, it's almost always a bad thing.

 

[sdavi66572]

My lenses are a combination of 90 and 120. I went a head and bump my lights back up to 62000 lux at the surface of water. I have not tried to use a zip lock bag to check at different levels. I will try and check tomorrow. Still in the process of getting my phosphates down, currently at .07. Im going to post some photos.

 

[mcarroll]

Nice!!

 

[saltyfilmfolks]

Yea super nice.
If I may, Id suggest looking into some more snails. My new batch of turbos just cleaned house on my powerheads, they look new.

 

[Syntax1235]

Got my meter in today... I had enough time to get a reading of my t5's.... The meter read between 185-195 on the x100 setting... What does that translate to par? The meter was approximately a foot from the top of the water and the tank is a 125 gallon, about 21 inches deep.


Edit:

ok.... so about 385 par (divided by 50) at waters surface... go down 12 inches and corals are receiving 96 ( divided by 4) par and at the bottom of the tank about 30 (divided by 4 again). Does this sound right? Again... this is from the t5's only. I need to wait for the weekend to get a reading on my led's when I'm home at peak intensity.

 

[saltyfilmfolks]

Got my meter in today... I had enough time to get a reading of my t5's.... The meter read between 185-195 on the x100 setting... What does that translate to par? The meter was approximately a foot from the top of the water and the tank is a 125 gallon, about 21 inches deep.


Edit:

ok.... so about 385 par (divided by 50) at waters surface... go down 12 inches and corals are receiving 96 ( divided by 4) par and at the bottom of the tank about 30 (divided by 4 again). Does this sound right? Again... this is from the t5's only. I need to wait for the weekend to get a reading on my led's when I'm home at peak intensity.

so, 20,000 divide by 40. What fixture and tubes? how high above the tank?

 

[Syntax1235]

so, 20,000 divide by 40. What fixture and tubes? how high above the tank?

It's a Pacific Sun Hyperion.... led with 4 t5's on each side of the LED's..

Each side of t5's is about 200 on the x100 setting. The light is about 1 foot above the water. I took the reading just above the water.

Tubes are ati.. coral and blue plus on one side and a coral and aqua blue on the other side.

 

[saltyfilmfolks]

That sounds about right. It should be about 400 to 500 par at the top of the tank.

 

[Salty1962]

you can purchase a meter with a submersible probe, or diy a ziplock etc. Mac And I have both found however that by measuring the surface intensity you can pretty well guage the penetration to the bottom.

Milwaukee MW700 is water proof

 

[saltyfilmfolks]

Milwaukee MW700 is water proof

you like it. huh.

 

[Syntax1235]

That sounds about right. It should be about 400 to 500 par at the top of the tank.

Then divide the par by 4 for every foot of submersion?

12 inches deep would be about: 125 par
Bottom at 21 inches: 35 par.

Sound right?

 

[saltyfilmfolks]

Then divide the par by 4 for every foot of submersion?

Im not sure on that one honestly.

 

[Salty1962]

you like it. huh.

I haven't received it yet but the reviews look good on it.

 

[Esage]

That sounds about right. It should be about 400 to 500 par at the top of the tank.

Whats a good LUX reading on a 16" deep tank with mostly softies and LPS? Should I be shooting for around 30,000 LUX? Would that be considered medium light and 20,000 Low light?