# Lights too bright for fish?



## corgifishkeeper (Apr 27, 2018)

This might be a silly question.

I have 20 LED lights for my 20G planted tank (cycling no fish yet), they are so bright that it blinds me if I look directly at them. My questions is, is this too bright for my fish also? Looking up from outside my tank you cant see the LED light directly and it seems ok, but what about when the fish look up from inside the tank, will they able to see the lights directly and will this harm them?


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## mgeorges (Feb 1, 2017)

How many watts? Most fish are ok with bright light, there are some that won't appreciate it however. I've got 96 watts total from T5HO on my 29 gallon...so you'll probably have no issues. If you do, frogbit and other floaters could help out your fish. And lots of plants.


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## jeffkrol (Jun 5, 2013)

not sure if this applies to ALL fish, but this is a physical thing.


> Fish acquire 'sunscreens' for their eyes through consumption of matter containing mycosporine-like amino acids, which are produced by plants, algae. A diet containing plant matter might be of benefit, especially when using UV LEDs.


some fish just don't really like bright light, or lets say prefer dimmer light, or more correct change..
Can't vouch for all or many though..
My tiger barb hangs vertical (odd fish) by the heater during full light, unless feeding..


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## Deanna (Feb 15, 2017)

I have about 200 PAR where the light enters the water, which is very high for fish tanks. Sunlight is over 2000 PAR. 

So far, I have seen no fish hiding, bumping into things, swimming with canes or using seeing-eye-dogfish. I think that their first reaction to too much light would be to hide. You are perfectly safe where you are.


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## jeffkrol (Jun 5, 2013)

My albino cory hides during higher light and my Angel prefers to sit under the sword during "noon" light..
Instinct mostly I suppose.. nocturnal and predatory..

When adding new brighter lights most of any fish I had (but guppies. nothing bothers guppies ever..) had some mostly minor reactions..
Staying lower , deeper in the shrubbery.. until they get used to it Just change or light?

They all get used to it for the most part.. but the cory..

Had to change my above post a bit..
Agree though that for the most part is a non-issue...

Most do hate lights snapping on full though.. different subject though.


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## Deanna (Feb 15, 2017)

jeffkrol said:


> My albino cory hides during higher light and my Angel prefers to sit under the sword during "noon" light..
> Instinct mostly I suppose.. nocturnal and predatory..
> 
> When adding new brighter lights most of any fish I had (but guppies. nothing bothers guppies ever..) had some mostly minor reactions..
> ...


The snapping on issue is definitely a shock to them, like tapping on the glass. Most of my catfish spend daylight hours hidden, so it's hard for me to tell if they don't like high light or just any light.

Speaking of the "snapping on", I seem to recall that you had an inexpensive dimmer for LED's. Can you say, again, what that is?


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## madcrafted (Dec 23, 2017)

Deanna said:


> The snapping on issue is definitely a shock to them, like tapping on the glass. Most of my catfish spend daylight hours hidden, so it's hard for me to tell if they don't like high light or just any light.
> 
> Speaking of the "snapping on", I seem to recall that you had an inexpensive dimmer for LED's. Can you say, again, what that is?


I like a nice sunrise/sunset effect myself. Fish/shrimps appear less stressed.

I use the TC-420 dimmer. It allows me to run a rack of tanks off one unit and it's a breeze to setup, once you are fluent in "chinglish". lol


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## jeffkrol (Jun 5, 2013)

Deanna said:


> The snapping on issue is definitely a shock to them, like tapping on the glass. Most of my catfish spend daylight hours hidden, so it's hard for me to tell if they don't like high light or just any light.
> 
> Speaking of the "snapping on", I seem to recall that you had an inexpensive dimmer for LED's. Can you say, again, what that is?


Any of the PWM cheap dimmers will work for most constant voltage strip lights.
There are a lot of "programmable" cheap dimmers..
Problem I have is my first one tried (like $10 was just a PIA. Specific OS (Android version) was required ect.
not sure if applies nowadays..

Prefer the TC-420 only because I know it. TC-421 adds "phone app" freeing from the computer..
8 bit dimming only and pretty rough.

Need to watch output though.
TC-420 can handle 4A per channel (60W roughly) 
Some can do 6A (90W)

Other nice thing.. an English 3rd party web site for tips...
TC420 Programmable LED Time Controller

Menu is annoyingly on the bottom.. 

Bump:


madcrafted said:


> I like a nice sunrise/sunset effect myself. Fish/shrimps appear less stressed.
> 
> I use the TC-420 dimmer. It allows me to run a rack of tanks off one unit and it's a breeze to setup, once you are fluent in "chinglish". lol


This helps..

http://www.tc420.net/


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## madcrafted (Dec 23, 2017)

I should also note (in case someone else stumbles upon this topic) that you will most likely need to upgrade your PSU if you intend to run more than one light from dimmer such as this. Probably not a bad idea to upgrade your power supply anyways, given the track record of most that are included with 'budget' LED fixtures.


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