Pool & room
Lighting the pool room
Light the room for the animal and the camera, not for you.
Lighting affects two audiences at once. The animal needs to see the cues around the room, and the camera needs an even picture with no bright reflections sitting on the water. The original editor's notes had firm advice here: two fluorescent strip lights with a diffuser for white pools, and for black pools four up-lighters of about 60 watts, fixed high enough (for example 6 ft from the floor) that the camera can't see them. You can read the notes in full on the editor's notes page.
Questions people ask
How bright should the testing room be?
There is no single correct level. Choose one for your test, measure it with a lux meter at the animal's level, keep it the same every day and report it. Open field protocols often use bright light (500–1000 lux); water maze rooms are usually moderate. Your local ethics committee, licence conditions and vet always take precedence.
More detail
Published values range from about 25 to 1000 lux. Examples: about 100 lux for a mouse elevated plus maze [Komada 2008]; 500–1000 lux for a mouse open field [Seibenhener & Wooten 2015]; bright light as the Barnes aversive stimulus [Gawel 2019]. UK guidance notes albino rats avoid more than 25 lux [Home Office]. Lux is weighted to human vision, so also record the lamp type [Peirson 2018].
Going deeper
Mixed evidence. Light raises anxiety-like behaviour, and albino animals are more light-sensitive [Peirson 2018], so a change in light between cohorts can look like a treatment effect.
How do I stop reflections and glare on the water spoiling tracking?
You stop reflections by lighting the pool indirectly. 1) Use uplighters, or bounce light off the ceiling or walls, rather than lamps shining down at the water. 2) Look at the camera image: there should be no white patches on the water. 3) Check the light is even across the pool. Your local ethics committee, licence conditions and vet always take precedence.
More detail
Water acts as a mirror, so a lamp in view of the camera shows as a bright patch that the tracker can confuse with the animal. HVS recommends adequate light, no specular reflection and even illumination, usually with low uplighters, especially for water mazes [HVS]. Uniform lighting that minimises reflections is a recommended parameter [Vorhees & Williams 2024].
Going deeper
Check uniformity with a lux meter at the centre and four points near the wall, and record both the average and the lowest reading: HSE uses average and minimum values for the same reason [HSE HSG38]. A dark pool shows reflections more than white water does.
What lighting should I use for tracking, especially in the water maze?
Use even, diffuse light with no reflections, usually from four short uplighters around the pool. 1) Place uplighters evenly around the maze, low enough not to be seen from the water. 2) Bounce light off the ceiling rather than onto the surface. 3) Run Check Lighting and remove shadows and glare before adjusting the threshold.
More detail
Good lighting needs adequate light, no specular reflection and even illumination across the surface. The most popular method is short uplighters with incandescent bulbs, which matters most in water mazes. Light reflected off the ceiling from a suitable distance works well; an uplighter too close to the ceiling acts as a direct source and causes reflections on the water. For Barnes and open field, aim for the table or floor to look close to white on screen, with no shadows or glare.
Going deeper
Support cases suggest four short uplighters spaced evenly about 2 m outside the tracking area; if they spill light downwards, place them below the level of the tracking surface. Cardboard deflectors under overhead strip lights are an alternative. In Check Lighting, black/white dots indicate shadow and red spots glare; fix shadows first, then glare, with the threshold at 100, before touching the threshold. Keep lighting unchanged throughout an experiment. Under a reversed light cycle, switch on the tracking lights before setting up, or the camera image will be black.
Are albino animals affected by lighting differently?
Yes. Albino animals are more sensitive to light and see less well, so keep lighting moderate and constant. Your local ethics committee, licence conditions and vet always take precedence.
More detail
Albino mice are more light-sensitive and have impaired visual function [Peirson 2018]; albino rats avoid more than 25 lux [Home Office] and have lower acuity [Prusky 2002].
Going deeper
Be careful when comparing albino and pigmented groups: differences may be visual.
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