I am new to this forum and I have been reading quite a few of the threads from other members and I have decided to move forward with a DIY ATS build. I am hoping to get some advise from those of you that have been doing this for a while now. First some background: I currently have a 120g built into the wall of my living room. My fish room is the adjacent room behind the same wall that holds the tank. I have a custom built sump from synergy which is ~50g. Pretty standard sump stuff, 2 filter socks, Reef Octopus Skimmer, external Iwaki return pump. I have another external pump, a pan world, that I was using to drive an activated carbon reactor and a GFO reactor. The entire system is controlled with an Apex. In the tank I have various LPS corals, a RTBA, a fox face, coral beauty, 6 line wrasse, 4 blue green chromis, a yellow eye kole tang, a cleaner shrimp, and several snails. I have ~100 lbs of live rock and the bottom is covered with ~2" of sand. I have had this tank up and running for 2 years now. In the first year or so I had a nice growth of beautiful coralline algae that covered most of the live rock. As the 2nd year progressed I started seeing less and less coralline algae and more and more green algae. The green mat of algae now covers most of the rocks but i can still see a bit of purple in a few spots. I typically do a 30% water change once a month. Phospate reads about .03 with a Hanna checker, I need to check nitrates again but if i recall in December when I checked it last it was about 10ppm. My water source is a BRS 5 stage RODI unit. I feed once per day with a about a cube maybe less some days because I have been trying to limit the amount. I dose BRS 2 part as well. I have been reading a bit about the great "sand or no sand debate" and I am wondering at this point if the sand is becoming a nutrient sink. At any rate I am planning to do a DIY build of an ATS here soon. I am trying to figure out what size screen I need and how many LEDS I should use. There is so much information out there and so many opinions it gets a bit overwhelming. That is what led me to your forum. You all seem to be very successful with ATSs and I think sticking with this forum will give me the best chance of success.