Refugium sand bed

[tricky]

Anthony,
I have a 30G fuge supporting a 180G system, it is well stocked chaetomorpha (grows like a weed), some LR and a DSB of 2" to 6" in. I have been very happy with its performance. The system has been up for around 6 months. Initially ther was a large population of the little white stars, lots of pods, orange bristleworms. I have not seen as many stars and pods lately, mostly the worms and the white calcerous tubeworms. I have noticed the sand in the fuge is real black just under the surface, even the bottom of the pieces of LR. I can vary the amount of water I divert from the display tank from a header at one end to an overflow pipe at the other.

The system has no particular problems right now, except for a bit of cyno. I have vacuumed it from the sand a few times, but I am now getting some on the LR. I suspect some overfeeding going on, and I tweaked the Euroreef to skim a little harder.

What is your recommendation on the amount of sand in the fuge? Should I dump it and reduce the amount? Any tips on the cyno?

Rick

P.S., it was great meeting you at MACNA, was hoping to see more of you!

 

[Anthony Calfo]

cheers, my friend

overall it sounds like you are on a good track with this fuge/system (awareness of possible overfeeding, flow issues, excellent skimmer on hand, good choice of macro for nutrient export, etc.)

in a nutshell... it sounds to me perhaps that you have the very common problem of inadequate water flow in this refugium. Are you noticing the cyano or like nuisance species mostly or only in the refugium but not in the display? I suspect so... and if this is like most refugiums, your flow is closer to 10X turnover rather than 20X+

The notion that refugiums = slow flow really chides me and is a misapplication IMO. Sure... lagoonal areas and quiet niches on/near a reef that we may be trying to simulate with such refugia/biotopes are indeed far less dynamic than the reef proper/crest, etc. But they still have a staggering amount of water flow in these areas... a "turnover" in a given range/zone on a scale of magnitude that is quite extraordinary.

As aquarists... we have interpreted the "lower flow" aspect of this dynamic inaccurately... grossly underestimated again IMO.

Increase the water flow in your refugium to around 20X for starters. This will keep solids in suspension longer for export mechanisms (filter-feeders, skimmers, mechanical filters... whatever) to process the matter better. This in turn will improve sand bed health/lifespan.

You also may not have to remove the bed... perhaps just turn it offline for a day or two (with aeration/circulation). During that time... stir/siphon the sand well to liberate some heavy solids and do a 100% water change (or two) during that time. When the tank is nicely clear 48hrs or so later... then turn it back online.

I'd also recommend that you have a minimum of 3" in the lowest spots for better denitrification.

Best regards! And hoping to see you soon

Anthony

 

[tricky]

Anthony,
Thanks for the input. You are correct, I had interpreted the "lower flow aspect of this dynamic inaccurately". Logic seems that the critters don't like light, don't like to be blown around, etc. I can definitely step up the flow easily, sounds like a solution to the issue in the fuge.

Actually, I have not noticed the cyno in the fuge, but it is hard to see with the placement in the sump. The cyno I spoke of is in the display tank. I am running about 15x turnover in the system, running 2 Iwaki 30s-- one in a closed loop with a sea swirl and a squid, the sump return through a manifold with 4 1" openings. Below I have a gate valve that will allow me to divert some overflow water into the fuge, and had it shut down significantly.

Thanks,
Rick

 

[Anthony Calfo]

ah, I see.. well - at 15X you are in a very fine ballpark, generally speaking. For most garden reef aquaria, 10-20X is a proper start. Some tanks will require more flow... much more for some like sps systems in fact.

But with controlled feeding, continued good skimming and some very fine water flow devices as you have, your cyano solution may simply be a matter of tweaking the effluents that you have for a better distribution/creation of random turbulent flow. A few dead spots is all that it takes for pockets of detritus to settle and accumulate in excess and fuel nuisance growths in time. This problem is amplified when we stack rocks up against any side walls (reef displays are easier to maintain in this regard when the rockscape does not touch the side walls and enjoys strong water flow all around the reef instead of having pockets for solids to filter down into).

Play around with the outlets. And if you have an extra power head or two, add even temporarily to see if it makes an impact - you should expect results from an increases in water flow in about 2 weeks.

rock on

Anthony