Technical Discussion - Refugium

[Rcpilot]

I have a CPR HOB refugium on my 30g tank. It's been up and running for about 2yrs. I have a DSB in the bottom of the fuge and a big chunk of cheato that I trim out occasionally.

But the whole refugium is starting to look a little ------ ummmm - dirty. I see a layer of dust or muck on the sand bed thats been slowly accumulating for 2yrs. I really don't want to disturb the DSB out of fear I may trigger a sudden cycle or worse, a dump of hydrogen sulfides into the water.

I have occasionally used a gravel vac to very lightly suck the top layer of muck and goop off the DSB. But I DO NOT plunge the gravel vac into the DSB - again .. there is a fear of releasing harmful gasses into the water.
Rule #1 of a DSB:
Don't stir it!!

I am considering taking my refugium off line and draining it. I would remove all the water and sand from the refugium. Refill it with a new bag of live sand from the LFS and then drop a hunk of cheato back in. Fire it up and let it run through it's cycle.

I DO have a nice DSB in the display tank and plenty of live rock. I am "hoping" that filtration would help absorb any ammonia or nitrate spike from the new refugium sand.

I've read articles that claim you should replace a DSB about every 2yrs. Some people claim the DSB is simply collecting detritus and slowly becoming a big garbage can. At what point do you change the sand bed?

Thoughts?

 

[dcantucson]

I replaced my DSB in June of this year after 1 1/2 years of it collecting garbage. I found it very frustrating in every aspect. I went with the Red Sea Base substrate in both my tanks and i am happy with it so far. The jury is out with it but I think it's going to be much better than the sand. I can vacuum it as needed without stirring up a bunch of crap yet it is compact enough that all the crap doesn't fall into it creating a gasses trap.

 

[Ted]

if you have a dsb in your dt then why dont you run the hob fuge with just some lr rubble? I only put rubble in mine and dont have a dsb in main tank. I did the rubble for pods but they all seem to be in the cheato anyway. I had my first trate 0 reading this weekend. Just a thought.

 

[Ithaca9]

This actually brings up an idea that I have. What about fitting the fuge with two containers for your DSB? Both can hold sand, then take one out every 6 months to a year, dump it, clean it, and refill it with fresh sand? After the next 6 months to a year, do the same with the other one. There's always a supply of established DSB, it's easy to remove and clean, and the live rock can sit right on top of the containers. I was planning on building two identical rectangular containers, 6 inches high, that will fit as snugly as possible side-by-side to fill up the refugium area, place egg crate over top of them, and put the live rock and cheato on top of that. Don't mean to hijack the post but what are people's thoughts?

 

[dcantucson]

As far as that goes one could just have a short divider in their refugium with a DSB in each one or each side. Then once every 6 months suck out the sand in one and replace it with new live sand leaving one side untouched. No need to have 2 separate containers or separate refugiums.

 

[project5k]

either way, the containers or the divider, it should help reduce the chances of a cycle.

as for cleaning it, personally i would just keep with the surface vac'n, and let it go, and i agree about the NO STIR rule on the dsb, Altho, i have to wonder, if you were using one of thoes rigid clear "aquarium vacuume" things, if, by stirring the DSB wouldnt any released gasses get sucked up, rather than turned loose into the system? I dunno, it was just a thought.

 

[Rcpilot]

I don't really have an answer to the question:

"If you have a DSB in the display, why don't you just remove the DSB in the refugium and fill it with live rock?"

I guess it never occurred to me. Seams reasonable enough though. You get a +10 for that one. :Cheers:

I DO like the idea of splitting the refugium into 2 compartments and changing the DSB in each compartment every 6 - 12 months. That seams like a much more viable option to me than removing ALL the sand at once and then filling it up with new "live" sand and waiting for the inevitable cycle.

How do you think my tank will do when I remove the refugium to perform this maintenance? Either way I have to disconnect the refugium and dump the sand out of it. Clean it. Then install a plexiglass divider to create the 2 different compartments. The refugium is going to be out of service for at least a couple days. Could be a week. That means no skimmer, no cheato and reduced flow in the tank. I guess I could double up on the water changes. I usually change about 5g or 6g on Sunday. I could remove the refugium on Sunday, change 5g of water and begin the work on the refugium. Install the "new" refugium after a couple days of letting the silicone cure.

 

[yote]

As long as your tanks been running,I highly doubt there would be a problem Rc.
The sand and rock in the display should be able to handle the tank for no longer than you'll have the fuge off.

 

[project5k]

yea, i'm in the same boat, when i finally get off my a$$ and put my tank on the new stand i built, i'm gonna be re-working my fuge as well, but i'm also gonna be completely draining my tank as well, so i'm sure that i'm gonna cause another cycle... i've just accepted it at this point, i just hope that its not too bad...

in your situation i would think that you would probably be ok for a couple days, just watch everyone for signs of stress, and you might think about picking up a small powerhead just to help out with the flow while the systems torn apart. then later on when you go back together, you can stoe that extra under the cabinet and save it just incase you ever need to augment your flow later on down the road, like say if a pump dies or something... know what i mean?

 

[Rcpilot]

I've got 3 powerheads in the tank already. Flow and water movement shouldn't be a problem. The more I think about it, the refugium seams almost redundant at this point. I don't really need it with the DSB in the tank and all the live rock. I've still got 720gph in the tank without the refugium hooked up.

Thanks for all the good advice. I freak out and worry too much. It's nice to have friends that can talk reason and sense into me. :mrgreen:

:Cheers:

 

[d2mini]

I'm wondering if a fuge is even of any real benefit?!
I have one now. Couldn't really tell ya if I'm any better off than I was before I had one. :dunno:

 

[yote]

JMO,BUT.
I think a fuge is one of those "I want" items.
Yeah they do give the pods a safe place to breed.
Yeah it will pull some excess nutrients out of the water.
But pods will breed in the live rock,back in places the fish cant get to.And if your doing your maintance like you should,then you shouldnt have that many excess nutrients in the water to begin with.

 

[d2mini]

Ya, that's what I've been thinking, Yote. I think I'm going to leave the fuge out of my next sump. If anything, I might have the "fuge" section in there but just to have a place for more live rock. Or I'll just put live rock around the skimmer or return pump which will have more room without a fuge.

 

[dcantucson]

I agree yote & dennis. That's why I don't have one in my sump. In it's place I have big live rock rubble.

 

[Ted]

well I like my hob fuge. Since I dont have a sump it gives me a little more water in the system and it does seem to be helping with my readings. Before the fuge I couldnt get trates lower then 20 now i am a 0. Of course my system is a lot newer then yalls so maybe down the road I might not need the nutrient export but its still nice to have the additional water volume.