UVA requirements

[Alex and the Redfoot]

There is an opinion that UVA is essential for tortoises, because it enchances their color vision, affects feeding behaviour and overall activity.

The typical lightning setup for temperate and desert species includes three components:
1. Incandescent bulb: visible light and some UVA, on for 12-14 hours a day.
2. Fluorescent tube: intensive UVB/UVA and fair amount of visible light, on for 2-4 hours a day
3. Ambient LED light: visible spectrum, 12-14 hours a day.

These three light sources and their timings closely mimic natural sun spectre distribution over the day (UVB peaks at noon, while UVA and visible light remain more or less constant from dawn till dusk).

However, for tropical species, like redfoots, incandescent bulb is usually omitted (since they don't bask a lot and we try to avoid the "hotspots"). And as such all-day UVA light is not provided (only coupled with UVB for some hours a day).

Is the deprivation of all-day UVA a valid concern? Does it really affect tortoise behaviour, circadian rhythms?

 

[ZEROPILOT]

This is a very good question for discussion.
But because my tortoises live outdoors, I can offer little help.
My Chameleons have UVA and UVB. But the UVA are there primarily for the live plants.

 

[Alex and the Redfoot]

A few thoughts (mostly to up a thread). I was thinking about three options, if UVA is essential:

1. Place an enclosure somewhere near the window (not under the direct sunshine, of course). UVA seems to pass through the glass and plastic (around half is lost though).

2. Add an incandescent lamp. It should be placed high enough to avoid high basking zone temperatures and make lightning ambient and not spot one.

3. Arcadia has "Natural sunlight" T8 tubes with 2% UVB and 12% UVA output. Perhaps, they can be used as a full-day lightsource. Either solo or coupled with daylight LEDs and UVB T5 tubes for a more natural sunlight simulation.

 

[Markw84]

Incandescent light bulbs put out virtually no UVA. The filament does not get hot enough to produce those wavelenghts. The light produced is towards the red end of the spectrum - 2500k or so. No UVA.

 

[Alex and the Redfoot]

Incandescent light bulbs put out virtually no UVA. The filament does not get hot enough to produce those wavelenghts. The light produced is towards the red end of the spectrum - 2500k or so. No UVA.

Yes, I should have checked Arcadia's claim for UVA output of their Solar Basking lamp before posting. Thank you! While there is some output in 380-400nm, it's really neglible... And as such, typical lightning setup for temperate and desert species lacks full-time UVA source as well.

That makes me wonder even more - is the UVA really essential through the day? How much is too much and how low is too low?