Should we worry about the LED flicker rate perception of any common aquarium species?

[JasonG1]

My wife just said "why do you think about all these things?!" I know...this might be silly. I'm curious if this topic has been discussed here.

I just happened to be researching LED flicker rates...see: What causes LED flicker

I'm far from an expert (actually fairly clueless), but wondered if we're potentially torturing certain species in our tanks under the LED lights.

Most LEDs flicker above the human perception level of ~50Hz so it "appears" to be a constant light source (but it's not). See the slow-motion video I attached of the LED lights in my office. You can see them flickering.

It seems the frequency most LEDs flicker at is about double the electrical line frequency (60Hz in the US). So the LED has 60 oscillations between negative and positive poles per second or (120Hz).

I found one article, in my quick Googling, indicating a type of shrimp that has fast vision and a sampling rate of 160Hz. See: Snapping Shrimp Vision
Then I found another article indicating the Sunfish samples at ~50Hz

This got me to thinking...how do we know we're not torturing some of our tank inhabitants with constantly flickering lights? I am searching for a list of vision sample rates by species, but not finding anything useful.

 

[JasonG1]

The slow-motion video I posted isn't playing properly...might just be me. Anyway...it does show the flickering.

 

[Idech]

I can’t see the video. But this sure is an interesting question. I do see flickering in my tank but I find it appeasing. I would think there is flickering in the sea as well, just not very deep.

 

[SteveMM62Reef]

I don’t see how this could be a problem with our Aquariums. The LED’s use 12 to 36 Vdc, the voltage is converted from AC to DC by Higher Quality Converters. Also the Light is refracted when it enters water, this will dampen any Flicker. At work, when we were converting Fluorescent Lighting to LED Lighting. Almost immediately started getting complaints on the new lighting, giving people headaches. A White Sheet was produced, there was Zero Flickering on Multiple Brands of the LED Retrofits. The only Flicker I have personally seen, wasn’t what I’d call a Flicker. It was a definite Cut out, Cut in due to the Driver Failing. One was a COB LED, and I replaced the COB and Driver. The other was a Toggled LED, that Failed. One out of 24 over a Five and half year period. Also I’ve never had a GFCI trip from LEDs. can’t say that for Fluorescents.

 

[JasonG1]

@SteveMM62Reef - that is a very interesting and good point. I would imagine the switch from AC to DC eliminates the sine wave oscillating of the current (that causes the on/off flicker). In fact...I just did a slow-motion recording of some of the DC powered LEDs in my house (tank, above cabinet lights, LED pucks I put in my tank stand) and they don't show any signs of flickering. So maybe DC powered lights eliminates this concern. Very cool and I didn't think of the AC/DC component here. Thanks!

 

[SteveMM62Reef]

Years ago I started replacing all my Lamps with LEDs. House is 100% LED, except the Oven. The thing I did find out is when Replacing Screw in Lamps, turn the breaker off, and with a no power detected at the fixture, pull the little center contact tab out. This will let the flat contact on the LED Lamp make better contact. A poor contact, can result in higher heats, flickering and a reduced lamp life.

 

[rhitee93]

I'm new to reefing, but an electrical engineer by trade. Most fluorescent lamps also flicker at the mains frequency, so this wouldn't be a new phenomenon to the aquarium hobby.

I haven't dug into the designs of the LED reef lights. However it is quite likely that they do not flicker at mains frequency for the reason SteveMM62Reef stated. However, they may have some flicker caused by the using PWM to control brightness.

 

[JasonG1]

I'm new to reefing, but an electrical engineer by trade. Most fluorescent lamps also flicker at the mains frequency, so this wouldn't be a new phenomenon to the aquarium hobby.

I haven't dug into the designs of the LED reef lights. However it is quite likely that they do not flicker at mains frequency for the reason SteveMM62Reef stated. However, they may have some flicker caused by the using PWM to control brightness.

I wonder if all the shrimp in tanks with fluorescent lights felt like they are at a 24/7 dance club with strobe lights going

 

[oreo54]

I'm new to reefing, but an electrical engineer by trade. Most fluorescent lamps also flicker at the mains frequency, so this wouldn't be a new phenomenon to the aquarium hobby.

I haven't dug into the designs of the LED reef lights. However it is quite likely that they do not flicker at mains frequency for the reason SteveMM62Reef stated. However, they may have some flicker caused by the using PWM to control brightness.

Most common pwm is around 500Hz
Depending on the driver it can be much higher in frequency.

You rarely can compare crummy house lights with any aquarium array even the constant voltage type.

I assume the switching power supplies have their own flicker rate.

The old magnetic ballasts had the usual line flicker. Some say, oddly, this is at 100Hz.

Not sure of the newer electronic ones but many have their own issues like emi.

 

[jda]

PWM is one of the main theories of why folks who run their LEDs at 100% often have more success with harder to keep species. Spectrum is a big part of this too, which is why it is just a theory.

Some people can see LED flicker like some can hear electronics that others cannot. I could see some flickering in some screw-in LEDs that I got from Phillips. It freaked me out until I found out that it not that uncommon. Nobody else in my house can see it.

Zoox are many times more sensitive than human eyes. Maybe the zoox care and will hire a 1-800 lawyer and file a class action lawsuit against EchTech and Kessil one day, but that is not today.

In the end, I do not feel that LED perform as well as other types of bulbs, but PWM is not likely one of the reasons why... but it might be fun to talk about.