First timer - brooder question

[twinmom+1VT]

I've been spending most free moments on this forum learning all I can in preparation for our first time raising chicks. We have the coop designed and hubby just got some building supplies today. We're getting 2 Buff Orphs, 2 Black Aust., and 2 Light Brahmas. I'm feeling a little confused about the whole brooder part. We found a large wooden box (i'll try to get dimensions) that we were going to turn into a brooder, complete with a screened lid. We were planning on keeping the brooder in the garage (my hubby isn't to keen on the idea of chicks in our spare room). The chicks are arriving May 7th and we usually have frost at night until early June. The garage is unheated and probably gets down to about 40 degrees at night. Will this get too cold for the chicks even with the lamp on? How long should chicks be kept in a brooder? What's the minimum space needed for 6 chicks? I've been reading a lot but just feel like I'm not finding a great deal of info in brooders specifically. I also have a small fish tank (I think it's a 10 gallon) that I could use when they're really little and I might be able to convince hubby to let me bring that into to house. Thanks for all your advice!

 

[rsf31tmp]

Even if they are very young when you get them, they grow super fast. I week or two in the fish tank inside would do. Then maybe a few more weeks in the garage.

I live in Illinos and my chciks were born in late Feb...in my basement until mid March and now are outside.

In my brooder, I had one 250 watt red bulb in my lamp. I took to lids off rubbermaid tubs and placed them on top of the brooder on each side of the lamp. They were very warm...even when below zero outside. There is no heat in my basement. Each week or even 3-4 days raise the lamp up a little. They will tell you if they are too hot or cold.
If all together under the lamp, it is too cold
If as far from the light as they can get, then too hot.

Today all 16 of my chicks are outside and they have one lamp....they sleep near the lamp, but are all over the place in the daytime.

I am no expert, but after my first month with chicks, I think this can help.