I have a 200amp main panel running the house, I added a 100amp sub panel(#1)to power my finished basement,I installed a 100amp breaker in the main panel and ran aluminum feed to power the sub panel#1. I only installed eight breakers and have 12 spaces left in 100 amp sub panel#1 (both panels are in the basement). I installed a 60amp breaker in the 100amp sub panel#1 and ran ROMEX(TYPE NM-B)6/3 with bare ground Wire(to feed the future 2nd sub panel in attached garage) to my single car attached garage(6/3 wire is in garage awaiting 2nd sub panel).
I plan on installing a pool and expanding the garage to a two car in the future. What type of sub panel in the garage can I install to the 6/3 romex wire? Can I use a 100amp panel? The second sub panel will only power lights a few outlets and a pool.