I was looking for a cheap LED light for my shrimp tank (54 liter/15 gallons). I decided to start a very simple DIY project to save money and to share it on instructables.

Stuff you need:

1 or more waterproof rigid LED strips; you'll find them all over the internet. I bought 2 of them at banggood (9$). The 12V rigid LED strips consume 9W each.

I do not trust the description which states 1400 lumen. Therefore, I bought 2 of them to be on the safe side. If the strips provide half the lumen as stated in the description, I will get around 25lumen per liter. I chose cold white (5500-6500K) which improves the green color of the plants.

1x Glue to waterproof the ends of the strips. I used UHU.

1x LED driver. In order to save money I used an old 12V RGB LED controller. You can use any 12V LED driver which is capable of providing 18W.

2x wooden/aluminum bars and 4x screws to install the light on top of the tank. I used small wooden bars and screws which I had at home. Aluminum bars are better, as the will help to give off heat from the LED strips.

So the overall costs of my project were only 9$. However, I didn't have to buy a LED driver.