Sharkky":58hu63t1 said:
Seriously and on-topic, I haven't been following all the hoopla regarding DSBs lately; boil it down--what is the newest thinking? Should DSBs be stirred occasionally? Won't that disrupt all the aerobic and anerobic denitrification layers and thus counteract one of the main benefits of the DSB? Or am I totally confused (wouldn't be the first time!)
I seem to be the proponent of stirring! But only if you have been doing it from the get go.
The idea, simplified, and the data seem pretty clear, is that a DSB is a sponge for phosphates, and that at some point the sponge fills up. When this happens the phosphates go back into the water and you have problems - algea blooms, and possible coral death (corals don't like phosphates). The bare bottom idea is to have a tank with LOTS of flow, so food and detritus never have a chance to settle to the bottom and rot, and so the skimmer, running wet, can remove them before they become a problem.
No one seems to be arguing aginst the idea that a 'dr' style DSB, where you never touch it, you skim little, that sand is deep, and the sand exports everything is a bad idea that doesn't really work in the long term.
My idea, and this is all my Opinion , supported somewhat in pm's with Galleon, is to remove as much as the detritus, through good flow and skimming and macros, as possible before it hits the sand bed and begins to rot. Some of it will still hit the sand bed. Through periodic 'stirring' - I have a 4 inch bed and I mostly 'stir' the top two inches - the detritus and phosphates get put back into the water where you filter it out a la skimming, filter
socks and canisterfilters. If you do it regularly, form the beginning, the danger of posioning the tank by disturbing the sand is low, and the sand doesn't get a chance to fill up and and crash the tank at a later time. The DSB will eventually fill up, but by 'stirring' and exporting, its useful time should be exteneded by oodles (some dr style DSBs seem to crash between 3 and 5 years from set up). This is all MY opinion, but I haven't seen any data to show I am wrong - still looking - but I could be wrong. I havent had any problems yet though.
If I were setting up a tank today, I would only use and inch or two of sand and I would only use it because I like the look of it. An inch or two would be easier to clean, and wouldn't be able to fill up as much simply because it is smaller.
And how does that apply to DSBs in refugiums?
It applies the same way, but if the sand is in the fuge, it shold be easier to remove, or change if necessary.
[/quote] I have a DSB of larger-chunk aragonite in the main tank and a good bed of sugar-sand in the 'fuge, and both seem to be working really well. When one of the clowns stirs up something in the main tank, though, there is a big swirl of detritus, so I've thought about 'storming' the main tank, but I'm fearful of all that organics being churned up into the system.[/quote]
I would be worried about 'storming' a sandbed that had been sitting for a long time for just the reasons you point out - its full of ickies. A gravel vaccum would be a better choice because less 'posion' would be introduced into the water. At the same time I would run a filter sock on the overflow and a micron cartridge, and crank up the skimmer to export the detritus from the bed.
Oh yeah, when I 'storm' I do it several times a day (takes 5 min) over the course of several days.
Gotta get on a plane, so I hope all that makes sense. I'll check when I get home later!
:mrgreen:
I'm gonna give it a shot...I'll let ya know how it goes.
