The Contentious Issues of Lighting

Lighting can be very contentious

Manufacturers seem to assume that the brighter is the better

But where in the world do you get cloudless skies each and every day and no obstruction tween ground or water and the sun

Nowhere.

My lights are not the ones that came with my aquarium, they are infinitely adjustable and my fish are the most active and colourful when the lights are on their lowest intensity....think along the lines of a cloudy day...yes there is light but its not harsh light, its not piercing light that you cannot escape from (even floating plants do not cut the intensity of the light, they only offer shade from it)

My light is a 78cm long Nicrew RGB MCR, cost me less than 35 quid. My fish don't get spooked or stressed when the lights go on and when the white light is on its cloudy day bright, so the activity levels are high, they are not getting spooked by their own shadows or the shadows of their scaping. The colours of the fish is vibrant, they don't hide away from the bright light as they did when I initially used the factory fitted light. I also do not have my light directly above them. It is sitting on the glass brace at the back and angled 45 degrees down....think cloudy day through the trees, no direct light, just soft lighting.

Sometimes it is not financially and/or physically viable to just change a lighting system that came with an aquarium, so what are the alternatives when your aquarium light is too bright and harsh and you cannot dim them down?

One very inexpensive and easy alternative is to use theatrical light film.

You can either sleeve the light or tent the film over the light (attaching the film to the hood with superglue)

Using film can also be an inexpensive way to change the colour of the light...rather than buy specific plant enhancing lights.

Theatrical film is heat proof and it is not affected by humidity...most importantly it is not toxic to fish should it fall off the light for any reason.

Theatrical film comes in a massive number of shades and intensities so you can find exactly what you want easily and quickly

This firm supplied my film before I found my Nicrew lighting and it really did make a difference to how the fish behaved but without affecting any plant growth


There are other companies who supply theatrical and stage in all countries of the world, the films can also be bought from various online suppliers too, but make sure that the films are theatrical/stage that are heat and humidity proof

The ones I used to drop intensity on the factory fitted lights....


I am sure there are other alternative ways to safely alter the intensity of aquarium lights too, so if you have other alternatives to adapt a light instead of changing it, do please share as there are many people who struggle with fish that are spooked by bright lighting.

I will just put up a photo of my naturally lit aquarium, very little artificial light. just think about the placement of the tank. The window in front of the tank is north facing, perfect for the southern hemisphere.

One thing I find interesting is when reading up on any fish I've researched, they all say they are "low light fish"... I have never heard of a mid to high light fish. Now medium strength lighting is fine, just not if its on the whole day... I just find it interesting that all fish I have researched say they don't like high light conditions.

If you consider that a lot of tropical fish come from rivers/ streams in the forest they will be permanently shaded by the trees. Little fish are more likely to prefer the smaller side-streams with roots and leaves to hide in than the open river.

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If you want to know who likes high or low light, ask the fish.

If it is silvery, what conditions would make that good camouflage? Silvery reflective scales are an adaptation to bright light. It's blinding up near the surface when the sun hits the water.

We have more low light fish in the hobby because we like strong colours, and the colours match the lighting. As well, most aquarium fish are small, and that says shallows. Small fish out in the bright light have to be in shoals or they're food. But sunny shallows are fish soup. In a rainforest under a canopy light is highly filtered and the water is often cooler, relatively. Vegetation from the stream bank will droop over the water where the sun does get through, and that also provides cover.

I haven't any time in the tropics, but I have spent a lot of time in and on the ocean, rivers, and lakes. Throughout that time there are only a few types fish that I have ever seen in open water. Resident fish mostly tend to the interface between the land and the water with fewer fish as you go deeper. The fish that are open water are usually the faster fish that are moving from one location to another, ie schooling salmon, herring, anchovies, etc, predators fit into this group as the typically have to travel further to acquire enough food. The problem is that we want aquariums that are well vegetated at depth.

In fresh water typically we have zones based on depth, margins where most of the plants grow with with most of their growth above water, this zone can be very bright depending on the location, but provides shelter from a number of active aquatic predators.

The next zone is the floater zone, where the plants are still growing in the substrate, but the leaves go to the top of the water column or rest on the surface. This zone is often very dark underneath the surface, this is the zone where I seen the highest number of smaller fish. It doesn't provide much shelter from aquatic predators, but effective cover from terrestrial predator.

The final zone is with aquatic plants growing on the bottom. Again this zone can be quite bright, but its brightness is affected more by the clarity of the water. Once you go too deep you don't really get any plants growing.

Obviously there is a lot of generalization in the comments but effectively with our lights, and plantings, many of us are trying to get plants from all the zones growing in a small area of 1 to 8 square feet, whereas in the natural environment each one of these zones might be measured in hectares. If you want a carpet of plants on the bottom of your tank you need high light, and you are effectively modeling the margin zone. People with lots of floaters, or jungle vals covering the surface are modeling more of the floater zone, this setup needs less light. @itiwhetu 's setup is a bit different because he is getting more light from the side, so he throws a cog into the mix, but it is interesting in that the front of the tank is the dark side, and that is where the fish are in his photo.

Most fish really seem to prefer darker zones, especially when they feel threatened, even the silver ones, so I view light intensity as the balance between getting the plants to grow, while affecting the fish a little as possible.

Lighting has been the bane of my fish keeping existence since forever. I agree fully with @itiwhetu . Placement of the tank is very important. I've been getting the bug to light one of my tanks and try my hand at some of the nicer plants. I've only ever had incandescent lights and the standard 15 watt fluorescent strip lights. Hornwort and duckweed always do well for me and I have also done OK with Java Fern and Java Moss. When I was a kid I had a five gallon with an incandescent top that got a couple hours of direct afternoon sun. I had Vallisneria that sent runners everywhere even in my shallow gravel substrate and little bubbles would come out of the leaves. Now, 50 some years later I can't replicate that. There's something funny about LED lights that I just don't like but people swear by them. There are also the High Output T5 fluorescent bulbs that really look like the cats meow but are expensive. If She Who Must Be Obeyed would just let me move my empire into our south facing living room with the big windows all my problems would vanish like smoke. C'est la vie.

This is my tank at lunchtime today with just the natural light, the Discus are all down the dark end of the tank tucked away resting.

wasmewasntit said:

Manufacturers seem to assume that the brighter is the better

But where in the world do you get cloudless skies each and every day and no obstruction tween ground or water and the sun

Nowhere.

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Ever been to Phoenix arizona or the Sahara desert? It is sunny and clear most of the time. even in the winter. Very different than the UK. you can still find aquatic plants in deserts. The Nile river is one such place. On a cloudless day at mid day a light meter will read about 20,000 lumens. Even on a cloudy day it is frequently brighter outside than the inside most homes. So many lights made for greenhouse or warehouse farms are very bright to match to get close to outdoor light levels but most of the time they stilll are short outdoor light levels.

itiwhetu said:

This is my tank at lunchtime today with just the natural light, the Discus are all down the dark end of the tank tucked away resting.
View attachment 158071

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The sun is off the tank now the whiptails are out and the Discus have just started to come out as well.

Those of you with brightly lit tanks how often do you see your nocturnal fish? How often do you see your fish just cruising, rather than swimming up and down your tank?

I have darty fish... Even with the light of they dart around the tank in all levels... Their curious critters...

Rocky998 said:

I have darty fish... Even with the light of they dart around the tank in all levels... Their curious critters...

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You have low light plants, try reducing the light intensity by 50% and see what happens.

Ive had the lights off for a week

itiwhetu said:

You have low light plants, try reducing the light intensity by 50% and see what happens.

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I just turned them back on today and the highest I will have it go to is 40% brightness