I am looking into upgrading lights, I have a 24 gallon nano cube, and am going to start a 3-4 gallon pico soon. I was browsing ebay and came across these, http://cgi.ebay.com/New-175-Watt-Metal-Hal...4#ht_537wt_1165 would they be a comparable alternative to the other (more expensive) MH out there? I could easily build something to house them in..

Would 175w of MH be too much for a pico? (I'm assuming yes)
Thanks in advance

not worth the heat and 70w MH is generally the most used on a pico
LED would be a MUCH better option now though
I'll be switching my pico over to 6-12 LED's this summer and expect to see MH level PAR while keeping PC low heat.

Yeah, the PAR 38's are incredible. Way less heat and WAY less operating cost. Get two of those and you would win TOTM and be labeled as a heroine due to the awesomeness of your tank.

I'd only need 2 par38's for the 24? I'm deff. getting one for the pico (in due time of course)

Two should work nicely. The NC24 (and similar tanks) are just a little too big to be properly lit by just one. Go with 60 degree lenses on both.

For the pico, a single 80 degree lamp will be more than enough. Maybe by the time you are ready to buy for that one, the new MR16 lamps will be ready.