Follow What LEDs do I need for a 20 gallon long reef aquarium? October 11, 2016 16:07 LEDgroupbuy Community Help What LEDs is required to run a 20g long reef aquarium for SPS? 1 Comments Date Votes Adam Brown August 13, 2013 18:32 The basic rule of thumb to do a reef tank LED setup is about 18 square inches of surface area per CREE XT-E LED (base colors) For a basic 20 gallon LONG which is 30x13x13 (LxWxH). This gives us 390 square inches of surface area (LxW). Divide that by how much surface area we want per CREE XT-E LED(18) we get just over 21 LEDs. In this case, sense the tank is so shallow, we can get away with 18 LEDs instead of 21. BASE COLORS: For base colors we recommend Royal Blue and Neutral White at a ratio of 2:1 (Royal Blue to Neutral White) Since our calculation above got us 18 LEDs at a ratio of 2:1 we need 12 Royal Blue and 6 Neutral White CREE XT-E LEDs (or just 6 of our custom 3UP stars using the 2:1 ratio or RB to NW) Thats all! This gives you the base colors you will need that will give you a great overall color and excellent growth. FULL SPECTRUM: If you wanted to do a high end Full Spectrum build you can also add the following to the base colors: We recommend a 6:3:3:1 ratio of Royal Blue to Neutral White to Hyper Violet to Ocean Coral White In our example we already have the 12 Royal Blue and 6 Neutral White CREE XT-E LEDs, all we need to add is 6 Hyper Violet and 3 Ocean Coral White to get to our recommend ratio. A good layout for this setup is three of the following: LEGEND: 2x Royal Blue 1x Neutral White 3UP Star Hyper Violet Ocean Coral White Powering the LEDs Powering LEDs is very straight forward. Have a look at this article on how to power the LEDs above: http://ledgroupbuy.zendesk.com/entries/25177163-What-do-I-need-to-power-the-LEDs- Please sign in to leave a comment.