What size tank is is and do you have live plants? If you dont want to grow live plants you can leave the light off until you want to look at the fish so that the algea dosent recieve much light.
BTW in your signature,you dont have all those fish (7 mollies 1 clown loach 1 plec 4 neons 2 tiger barbs and 1 bala shark) in the 33l tank do you? 33litres is about 6 or 7 gallons which is not big enough to support anything more than around 4 of the mollies or the two tiger barbs and 4 neons,the plec clown loach and bala shark grow far to big for that tank.