Chaeto questions

I am new to growing chaeto so I have a few questions maybe someone can help me with.

I have a ball of chaeto in the corner of my sump with a 100watt uvb reptile bulb on it about 10 - 12 hours at night and off during the day. T he light is about a foot from the algae. Heres the bulb specs http://ift.tt/2qvPB53

I have had it going about a week like this and have noticed the top of the algae seems to be looking a little grey in color.

Is this light too much for it?

I read a lot of people use 6500k lights, should I switch to one of these and where can I get a cheap one( the bulb is in a clip on reflector from the hardware store)

Does the algae need more flow?

Is there something else going on here?

Should I not worry about the color change?

Thanks in advance