How to successfully keep SPS Corals!

[Sangheili]

While this thread is great I feel like its worth discussing Lux vs PAR again. Its my understanding that PAR measures the light spectrum used by photosynthesis (Chlorophyll A/B/C) while Lux measures "human perceived" light intensity. The two are very very different.

Example: Lux will be extremely high for red/white spectrum lights but very low for actinic. PAR will be the opposite. Most corals have very little use for white/red light and the graphs for Chlorophyll are greatly skewed to the blue side.

I have not tested it, but I would expect that 10k lights have dramatically higher Lux then 20k lights. This is not at all a good representation of usable light your corals are getting.

PAR meters are an incredibly useful tool, and they aren't that expensive if you buy just the sensor and use a multimeter. You can have a full Apogee setup for under $150. Some of us have single Acro frags we paid that much for...

 

[mcarroll]

Too caught up in the theory and 'net wisdom.

In fact, PAR sensors are calibrated to daylight and misread reef lights.

Try using a lux meter - it's by far good enough.

That one costs only $15 makes having one a no-brainier.

 

[Tek]

Too caught up in the theory and 'net wisdom.

In fact, PAR sensors are calibrated to daylight and misread reef lights.

Try using a lux meter - it's by far good enough.

That one costs only $15 makes having one a no-brainier.

I used the phones LUX meter to set the LEDs and it worked great but others had trouble getting most apps to calibrate. I also used the readings from a 250w MH as a baseline. It may have been one of your posts which I got the idea from.

 

[mcarroll]

I used the phones LUX meter to set the LEDs and it worked great but others had trouble getting most apps to calibrate. I also used the readings from a 250w MH as a baseline. It may have been one of your posts which I got the idea from.

Probably was me.

I think there's a lot of variability in smartphone lux apps due to the lack of control of some cameras' apertures. They sense the bright light and auto-correct, ruining the reading.

I pretty much only recommend a $15 handheld lux meter cuz of this. (Simpler and still very cheap.)

Myself, I had good luck with one app but then no luck with a few others. Fun to play with since they are free (beer) but if you don't wanna play and just wanna measure lux...get a handheld.

 

[las]

Are sps and chalices ok together? Or would I be sacrificing the needs of one at the expense of the other? I would be limiting the tank to just these two species.

 

[mcarroll]

Are sps and chalices ok together? Or would I be sacrificing the needs of one at the expense of the other? I would be limiting the tank to just these two species.

Both are stony corals, so they will share many or most care requirements. Depending on the specific corals you choose they may have somewhat differing preferences for light and flow.

Keeping this in mind, go slow in stocking so you have a chance to figure things out for each coral before fully loading the tank and you should be fine.

 

[JBNY]

Too caught up in the theory and 'net wisdom.

In fact, PAR sensors are calibrated to daylight and misread reef lights.

Try using a lux meter - it's by far good enough.

That one costs only $15 makes having one a no-brainier.

That is not really true, Apogee uses daylight to calibrate their meter but that is only because it is a known value. A PAR meter evenly looks at the all the visible light, a LUX meter mainly looks at green light and places a much less value on the other spectrums (red and violet/blue the least).

 

[mcarroll]

The idea of calibration is to tune the tool for what's being measured, so I'm not sure I buy that idea.

I also do not think a PAR meter looks evenly at all visible light. I've read that cheap ones we're familiar with look at photosynthetic wavelengths.

None are tuned to look at the bizarre light we cast over our reefs...which is neither like daylight nor very much like sub-surface light in the ocean.

If you have a link that explains otherwise I'd like to see it.

Of course, the point is that I've successfully been using a $15 lux meter where most are thinking they need a $xxx PAR meter. (Which is just not true.).

OTOH, the point is not that either handheld meter is scientifically accurate, because neither is. Accuracy in light measurement is >$xxxx.

 

[JBNY]

A PAR meter looks at light like this

A LUX Meter like this

They measure the light very differently, not saying you can not be successful using a LUX meter, just pointing out the difference.

But a PAR meter can absolutely measure the wacky light we are putting over our tanks. A Li-Cor meter will off by just a few percentage points, but even the Apogee is only off by, at most 10-13%.

 

[mcarroll]

An Apogee looks at it like this:

Li-cor's may be somewhat idealized, or it's simply a better sensor. (More $, so not hard to imagine.)

For some detail on the low-points of measuring non-daylight light (even worse: light from LED's), check out Apogee's page:
Light Intensity Measurements for Light Emitting Diodes (LEDs); Correcting for errors

Not as bad as I remember (think they've improved things....good for them!), but also not (IMO) worth the cost of 20 lux meters. ($15*20=$300)

If you're Dana Riddle and need to collect accurate light measurements for scientific/mathematical reasons....probably worth it and necessary.

If you're trying to decide how far up to turn your lights, a $15 lux meter works fine.

The upside is that we don't really need accurate, merely repeatable. The lux meter delivers. Everyone should have a lux meter. One should be packed with every reef light.

So many people guessing at their intensity from eyeballing it and then bleaching corals....$300 is too expensive and net-wisdom poo-poos the $15 option, which would work fine.

End result is that most people just go on guessing. Unfortunate state of things, charts-be-******.

 

[gettaReef]

I recently got a LUX meter, type is made by Milwaukee Instruments (doubt that matters) but really have no idea on how to use it for my reef/ how to use it to dial in my LEDs. Would you mind explaining how to use a LUX meter to adjust light intensity or point to where a walk through can be found? Thanks

 

[JBNY]

Yeah the Li-Cor is very expensive compared to the Apogee.

You can use a LUX meter, the person just needs to be aware of how it measures light though. If you are only ever using it to measure light in your own aquarium, it's probably fine. It you want to compare your light intensity to someone else and they have all blue light and you have full spectrum, it might not be as useful. But something is better than nothing. Not everyone wants to spend the money on a PAR meter. For me I think it's worth it, it allows me to take a coral from someone's tank and know the exact light values it was under regardless of lighting and match it in my system.

But yes, I agree people should at least have a LUX meter, it can save them from bleaching their corals.

 

[mcarroll]

I recently got a LUX meter, type is made by Milwaukee Instruments (doubt that matters) but really have no idea on how to use it for my reef/ how to use it to dial in my LEDs. Would you mind explaining how to use a LUX meter to adjust light intensity or point to where a walk through can be found? Thanks

It's quite simple.

1. Measure at the water line (carefully).
2. Tune the lights to about anywhere in the "full sunlight" range. About 30,000 to 80,000 lux is a good target, according to your corals and your tastes.
3. Remember, more isn't necessarily better. A pretty wide range is acceptable.

http://en.wikipedia.org/wiki/Lux#Illuminance has a nice table of lux references.

 

[gettaReef]

It's quite simple.

1. Measure at the water line (carefully).
2. Tune the lights to about anywhere in the "full sunlight" range. About 30,000 to 80,000 lux is a good target, according to your corals and your tastes.
3. Remember, more isn't necessarily better. A pretty wide range is acceptable.

http://en.wikipedia.org/wiki/Lux#Illuminance has a nice table of lux references.

Thanks for the walk through....I'll get it out and give it a try. I switched from MH+T5 to LEDS a few months ago, starting with low intensity and slowly increased to where I now max out at little over 50% white and 60% blue. My corals have responded well and have been growing at a good rate but I'm clueless as to whether or not I should increase them more. Hence buying a LUX meter to get some idea. I'm curious to see what the lux level is at right now. Now am I aiming for the 30,000-80,000 lux range at the peak intensity of the leds during the day? And, on average, how long would you recommend it being at that peak level during the day (1hr, 2hrs, 4hrs? Think now my lights are at max for 2 hrs)? Thanks again!

 

[mcarroll]

The sun is up for around 12 hours in the tropics, but for my setup I assumed that peak intensity was only for a few hours or less.

I have one tank that has ramping so it gets close to 80k lux at peak from my 160w razor.

The other tank (DIY w/30° lenses) only has simple on/off and runs 25-30k lux for 8 hrs per day.

SPS grow/look fine under both - even at the bottom of a 19" tank.

 

[gregcoyote]

PAR meter is worth the purchase if you are cultivating lots of coral and buying and selling frags. The meter takes much of the guess work as to how bright or dim my lights really are. I cultivate corals for a few years in a frag system before moving them to the display reef. The meter makes it a snap to get the coral the same lighting after the move. Then all you need to sort out is flow and proximity to enemy corals.

But a LUX meter is also useful. You can even use the meter in a older SLR camera to measure areas of the tank. You just need to convert ASA/fstop/shutter into a LUX measurement. There are also older light meters in EBay that also measure LUX.

 

[revhtree]

We must keep this thread going!

 

[Squamosa]

Since light seems to be the main topic here, I'll weigh in with a bit of data collected from my own tank.

Corals photographed are 150 mm from water surface.
Light source: Radion Gen3 pros, all channels on, 90% intensity, 10 inches from water surface.
Method of water management: DSR

 

[gettaReef]

Wow, that's some high PAR, corals look amazing

 

[that Reef Guy]

Great Thread.