High light can be a major catlyst for algae as many newbies have found out the hard way, unless you match that with a good fert program like Estimative Index, good substrate(ADA Aquasoil) and consistent c02 levels, preferably through pressurized c02. This also applies to 5 gallons(been there done that).
FWIW, through experimentation I found that I obtained best results on my 5 gallons with 14 watt 6400-6500 K compact fluorescent bulbs, any higher than that even with a 8 hour photoperiod resulted in a number of green spot algae patches on the tank walls. This was for a low tech Tom Barr type setup, no c02 injection, but regular/daily dosing of Seachem Excel.
If you really want to monkey around with light and want to avoid potential algae issues, you can start with high intensity and keep the photoperiod really low, increasing it by say 30 minutes a week to see where it takes you.