I am setting up 29 gallon and am racking my brain trying to figure out which size light I need. It’s going to be a low tech tank, no CO2, with a dirt substrate capped with 3 inches of BDBS. I have decided on the hygger 957 LED’s because of the cost and ability to dim the lights as well as the ability to set my own lighting schedule. The 24 inch(36 W) will leave 3 inches on each side but I am able to raise the light up if that would help with the spread of the light. I guess my question is, do I really need to have the light run the entire length of the aquarium?