I suggest you give the little red-foot some un-filtered sunlight (if weather permits – put him outside in direct sunlight). Just make sure he can move to a cooler place.

The other option is to purchase a UVB light – I would go for a mercury vapor light. They are better than the fluorescent tubes – they produce heat and heat is important with D3 syntheses.

I keep yellow foots (Very similar to red foots and some say they are the same species) and I give them about 3-4 hours of UVB light each day. I increase that if I find their shell feels a little soft.

Also if you give Calcium - try some with D3 – Red foots get a lot of their D3 requirement from their diet. – Also cutlet fish is also good – it wares down their beak and is a great source of calcium.

Good luck