10.0 UVB or 5.0 UVB ? RES bask area

[Bluemonster107]

I am constructing an additional dock area and need to replace the Combo Hood with bulbs and wondered which one I really should be using? My reptiles use the "strip type" bulbs but not feasible in the Red Ear slider bask area, so I use the combo domes. One of the Bulbs is a 75w splash guard bask light and the other one is a 5.0 UVB.... so just making sure that the 5.0 UVB is okay for the RES? .... as I was under the impression the 10.0 was more for 'desert type' reptiles and would be too much at 10-12" above bask platform...... again... just double checking since everyone here is so helpful!!!

 

[Markw84]

The difference between the 5.0 and 10.0 is simply the percentage of UVB in the total spectrum put out by the bulb. So of the "light" put out, the 10.0 is 10% UVB and about 30% UVA, the rest visible light. The 5.0 is about 5% UVB, 30% UVA and the rest visible light.

Sounds like you are talking about going with compact fluorescents for this application. For a larger enclosure like yours, I do not like the compacts because of the height of the dome itself. Plus the amount of UVB put out is very small and limited to an extremely small area. Fine for smaller turtles with a small basking area. The 5.0 would be mounted about 6" from shell height, the 10.0 about 8".

I much prefer the tubes for what you are describing - a 125 gallon tank, I believe. A fluorescent T8 18" fixture would give a nicer basking area combined with a low wattage incandescent flood bulb. The 5.0 T8 would be mounted about 8-9" and the 10.0 about 12-13".

Turtles often bask while floating on the surface of the water. I like to have the UVB source mounted so a portion of the "basking area" is actually over water. The time required for UV absorption is quite little, and the formation of pre-vitamin D is done in a matter of minutes. The bulk of the basking time is for thermoregulation, and the need to heat the skin so the areas of the legs can convert the Pre-D to D3. That takes a few hours with HEATED skin.

Red-ears also get a fair amount of their D3 from diet, so the UVB is not quite as critical. However, I do believe the UVA is vital for optimum health, and I almost consider the UVA the key source I am trying to provide in a good turtle enclosure, especially for older turtles.

 

[Bluemonster107]

Thank you Markw84!!! that is a very helpful explanation of the functionality ... and yes... I was referring to the compact fluorescents that screw into the 'domes'. I wanted to give the turts plenty of swim room so the bask platform is above the water with the bask light and UVB, so they can get out of water and dry a bit and soak up the 'fake sun' .... I just built an additional 'platform' for the other end of the tank, as I have expanded (in process) from the 60g to the 125g.... thus resulting on verifying the correct size of UVB bulb (the 5.0 or the 10.0)..... the light hovers over the platform at 10" currently, but can adjust higher or lower if needed.