If your friend gets a BN Pleco or any other type of Pleco, he will have to get a piece of driftwood since all Plecos suck/bite driftwood to sharpen their teeth. Get some Rotala Indica. This plant will thrive in any light condition and will grow very fast. The rotala indica in my low light 20 Gallon Planted FW with a 18watt bulbs grows on an average of 3-4 cm per week without CO2 and with a dose of flourish once a week.