I removed my cryptic refugium this weekend...

[Chad]

When I set up my tank the most recent time (almost three years ago now), I decided to try a few different techniques and setup changes that I had not tried previously. One of those things was a five gallon cryptic refugium.

 

My cryptic refugium is basically an acrylic box that I previously used for kalk topup in my old sps reef and then as a Borneman surge device. I converted it to "cryptic" by carefully wrapping it in two layers of tin foil and reinforcing the tin foil with clear tape over the entire outer surface and duct tape on the corners for edge protection. Finally I added a few pieces of rock and a little live sand.All of the overflow from my DT went through the cryptic refugium before going into my sump tank.

 

I was doing some deep maintenance this weekend and thought to myself: "I havent even looked in that box in over a year, there is probably some really cool stuff growing in there, let's check it out..."

 

So, what did I find? A ton of those tiny pineapple shaped sponges, tiny fanworms, and THREE INCHES of detritus... Aha! That is where the slime algae I have seen recently is probably coming from.

 

Since I didn't see anywhere near the cool stuff (sponges, tunicates, etc.) that I was hoping to see and it seems that it was just a big detritus trap, I decided to remove the cryptic refugium. I probably won't include one on future tanks.

 

Has anyone tried a cryptic refugium with good results? They were all the rage 5 years or so ago, but I haven't heard much about them recently. I wonder if others have had experiences similar to mine and I am just behind the eight ball on this one.

 

 

[roni]

i think the key to any fuge is slow flow through them but not necessarily slow flow within if that makes sense.

 

i wonder what would have happened if you had a very small powerhead that was set on a timer to go off for 2-3 minutes at night every day?

 

would probably kick up some sand and nutrients that would then become filter feeder food and prevent buildup while still preserving the cryptic nature of the fuge.

[Chad]

That could be, I don't know for sure... the box had ~600gph through it, but I doubt flow in the box was turbulent as it was through an overflow tube into the box and out of the box through the safety drain on a standard toilet flush valve. Interesting thought regarding the small powerhead... it almost makes me want to set it back up! If I get the urge to set it back up again, I will implement that idea

 

I know exactly what you mean about slow through but not necessarily in... it is how I set up my main refugium. There is about 600 gph running through it, and a rio2100 adding a ton of flow in it... I have really great growth on my chaeto and tons of 'pods.

[Origami]

You need a drain down low on that tank, Chad, and use it as a sediment trap! The drain helps to clean it out from time to time.

[Chad]

It would work well for that, haha, just open the flapper on the flush valve IIRC, ~3.5 of the 5 gallons drain in around 8 seconds... Somewhere I have pictures of it in use as a surge device.

[Origami]

It would work well for that, haha, just open the flapper on the flush valve IIRC, ~3.5 of the 5 gallons drain in around 8 seconds... Somewhere I have pictures of it in use as a surge device.

There you go. Just plumb it into the toilet bowl and literally flush it clean.

[beatle]

I locate my refugium after the skimmer so the water is somewhat cleaned before it could possibly be trapped. I'm also using a very fine DSB so worst case, I can still siphon off detritus if it accumulates.

 

Why cryptic and not lit for macro?

[Chad]

I am a subscriber to the "refugium volume around half the tank's volume" theory. When I set up this system I initially added a 30 gallon lit macro refugium, then later the 75 gallon "sump" that was to be dedicated to seagrass. The cryptic refugium was a third addition of extra volume to the system (and something that I hadn't tried before). Since I already had a lit refugium, I figured I would play with it. Also, at the time there was no form of mechanical filtration running anywhere in my system, so installing it before or after the skimmer didn't really matter since it was never running.

 

My system also usee fine sand in the DSBs (two, actually) and I routinely stir a bit and siphon parts of each of them, although detritus doesn't really settle on the sand (there is a pretty high amount of flow over both sand beds... an MP40 in the 50 gallon sump tank and a rio2100 in the dedicated lit refugium). I do find a fair amount in the chaeto, though (I guess it is dense enough for detritus to settle within it).

 

Overall, I think the system is better without the cryptic refugium that was really a trap for sediments (as intended, but I hoped that there would be more life in the cryptic refugium utilizing the sediments)...

[GraffitiSpotCorals]

I run a 40 breeder with sponges and a deep sand bed on one tank. I think it does a good job, plus its easy to feed the sun corals in. Never had a problem with detritus because of the way I set up the flow in it. I haven't decided if I will use the same concept on the new tank or not, thinking about just using cheato since there is not much room for everything under the tank.