Ok, so this may be a repeat but I've read through the past "what is that" posts and hope I can provide enough info up front for a diagnosis. These pics are from my 55 fowlr tank that I am in the process of completely re-plumbing and overhauling. The maroon and green growth is on the few existing pieces of LR, and is appearing on the new pieces. It is very close growing, does not seem to be getting long or hairlike and is not capturing or generating airbubbles. I don't have the luxury of cycling everything empty then stocking slowly. It was given to us running (barely) and stocked (the critters that hadn't died yet, at least) I broke it down, transported it and set it back up in about 2 hours, saved most of the water, and then started trying to update the system. I updated the light from a single old t8 daylight bulb to a new fixture with an electronic T5HO ballast driving one 410 actinic t8 and one 50/50 daylight t8 bulb. I run them on a 12 on/12 off timer. The 'fuge is lit by a pair of 23w CFL 6500k bulbs about 4 inches above the center of the fuge, on the same timer (for now). The system had a fluval 305 canister filter, and I left that running as is while I added a 20 gallon sump with about half the volume set up as a 'fuge. I filled it with about 7 or8 pounds of LR crumble and pieces, and some chaeto and Fern Caulerpa. Since I got the sump up and running I have cleaned the canister and completely removed the filters, letting it free flow through two trays of granulated carbon and the original tray of ceramic media. It had two packets of fluval nitrate remover in it originally, but I took them out assuming they were saturated. (currently soaking in fresh water in case they might be refresh-able) . The Macro is fairly recent, but I'm concerned that the chaeto ball is getting covered with what looks like maroon hair algae and has not grown visibly in a couple of weeks. And no,unfortunately I don't know what the nitrate and phosphate numbers are. The maroon algae is also showing up on a piece of LR that I moved from the DT down into the pump, even though I'm not seeing it in the DT yet. I had to add some makeup salt water from well water when I moved the system a month ago but since then have been using RODI from the LFS both about 15g premixed and buffered sw when I added the sump, and as top off freshwater since. The Diatom bloom I saw right after adding the well water tapered down to a minimum, and I'm now seeing the green and purple growth up in the DT and the limited Maroon hair in the 'fuge. So; what do you think? What is a good next step? What are danger signs to look out for? All input welcomed.