Today on BRStv, we are launching a brand new series: BRStv Investigates. In this series we will explore popular reefing theories, products, methods, and what the manuals are missing, with a focus on putting them to the test! We're looking forward to covering topics like: How long do T5 or halide bulbs last? Do bulbs shift spectrum and if so, does the yellow or red spectrum actually grow more algae? Do grounding probes work? Do certain corals thrive in high nutrient environments? Does high nutrient environment mean amino acids, proteins and carbohydrates or just high nitrates and phosphates? Can chaetomorpha or zeolites absorb ammonia directly? Is ORP really a good measurement of tank water quality? Do LED lights really last ten years? Are Dual junction PH probes more accurate? Do popular tank cycling products like Biospira work? This week we are talking metal halides: "Does a single 250 watt double ended bulb perform as well as a 400 watt single ended bulb?" Many reefers claim they are basically the same as a 400 watt single ended which seems almost impossible when the 250 double ended consumes roughly 40 percent less power. It’s hard to imagine how that could really be the case but that’s what we are going to test today. Does a single 250 watt double ended bulb perform as well as a 400 watt single ended bulb? Reflectors play a huge roll in this and there really isn't a perfect option that’s designed optimally for both bulbs so we are just going to do our best. Our two basic options for what we had on hand was the Hamilton Cayman sun which comes in a pretty similar form factor for the double ended and single ended version and the Giesemann Infinity and Spectra fixtures. To measure PAR we are going to use the Licor PAR meter equipped with probes designed to be used underwater. We ran a quick initial test under air, fresh water and seawater and found that the water not only impacted the strength or intensity at our measuring points but also how the light is refracted or distributed. Since we are all using the lights on tanks filled with water we elected to measure them in that environment. We saw almost no difference between saltwater and fresh water so we are testing in freshwater that is easier, doesn't have as many elements which can impact results like precipitation, and friendlier to the expensive equipment we are using. So follow along as we answer today's question, provide some helpful insight, and help make reefing just bit more fun and easy for you and your tank. *Legal Stuff* The purpose and content of this video is to provide general information regarding the products and their applications as presented in the video. Aquatic sales solutions, inc. And its officers, directors, employees and agents disclaim all express or implied warranties, in any way, related to the products and their application as presented in this video, make no representation or warranty regarding the products and the application as presented in this video and shall not be liable for any direct or indirect losses or damages of any type, including but not limited to punitive damages, or from personal injury or death resulting from or in any manner related to the video, and the products in and contents of the video. The viewer expressly agrees that aquatic sales solutions, inc. And its officers, directors, employees and agents shall not be liable for any damages or losses related to the products in and content of the video and hereby agrees to hold the foregoing harmless from any such losses or damages.