I guess I'm kind of weird when it comes to what I do with my refugiums. First, I'd better explain the tank setup.
My tank is a 5 year old tank (or maybe 6, I always forget which) that was moved 3 and a half weeks ago. It was filtered with bioballs, sponges, activated carbon, and protein skimming when I got it.
The overflow is a CPR dual 1 inch overflow, connected to a siphon pump. I don't really need the pump on there as long as I have the air tube sealed, but I haven't taken it off yet. I have a mag 24 with about 6 feet of head. There is a T that currently diverts flow back into the sump. That will connect to the remote deep sand bed.
In order to increase the growth of everything (including microalgaes) in the tank, I deliberately left the skimmer out and slightly overfed. Bioload is light for a 180, so it hasn't been difficult.
This weekend will be 4 weeks that it's been running at my place, so I am going to start setting up my refugiums and RDSB.
The remote deep sand bed will have 120 pounds of regular silica play sand in a 27g container, unless I change my mind again. The flow will come from a T on my return pump, diverting about 1000 - 1,200 GPH, and will return to the sump via a gravity drain. This is for nitrate reduction only, no aragonite buffering.
I currently have two 15 gallon long tanks to use for refugiums but I will probably switch to 20 longs because I want a 5:1 ratio between display and refugium.
When I finish the stand for the refugiums, they will be fed from the 2 line external overflow on the back of the 180g display tank. The refugiums will be set up as displays, as well, because I'm obsessed with invertebrates, apparently. Each of the two lines will go to a seperate refugium and each refuglium will have drilled overflows that flow back to the sump.
The first refugium will be a mangrove refugium, using red mangrove pods in my own special mud recipe with some small pieces of LR for bristle worms to crawl in. I'll also have "cleaner clams" in this tank, in addition to the ones I have in the display tank already. I may have snails in this tank, but I expect most of the cleanup to be done by worms. This refugium will have a 32 or 40 watt T8 lamp, depending on the sizes available.
The second refugium will be divided into two sections. The left side, about 70% of the total refugium space, will have 1.5 inches of sand with a variety of slow growing macros, like ulva, turtle grass, gracilaria, shaving brush, and so on. The other side (30%) will be 1/2 inch of sand covered with 3 inches of live rock rubble. I'll have chaeto over the rubble. I'll have snails in this tank, but no hermits. This refugium will have two clamp on shop lamps running 6500k halogen flood lamps.
The purpose in the different macros in the second refugium are to grow and propagate for the main tank. I broguht Mr Tang home from the tank at my office and he'll tear through the plants as I move them over.
If I get all of this done by the end of my vacation next week, I'll get somebody to take pictures of it and post them here.
PS, the carbon and sponges are coming out when the refugiums come in and I'm going to divide the bioballs up into four nylon bags to make cleaning easier. Detritus that makes it to the sumb past the clams, worms, and snails, will stick to the nylon bags while water flows through the bag and into the bacteria colonies living in the bioballs. It makes it easy as the dickens to do a cleaning rotation on the balls and, when I did this on my 75 gallon tank, I never once developed a nutrient sink in 3 years.
Low-range nitrate test is ~0.2ppm, phosphate is ~.03ppm using salifert test kits. I don't run any phosphate removers in the tank. I have found that I have to dose iron periodically to keep the chaeto from turning yellow, and it grows slow and steady, hopefully because it is nutrient limited.
