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 Posted 1/16/2006 1:05:52 PM |
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| for a 90g tank... a 3 gall pail of sand with say 40lbs of sugar-fine sand might work nicely IMO. Drill it and fill it as per the thread details mentioned in the link above. kindly, Anth-
. Anthony Calfo
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| Posted 1/16/2006 3:02:37 PM |
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| I'm closing in on my 90g upgrade. I think I'm just going to go with silica sand for my RDSB. I can't find a cheap source of aragonite based sand, so this is the best way to go. When I was at HD yesterday I did find two types of silica sand. One was the regular Quikrete play sand, and the other was just "all purpose sand." Anyway, the all purpose stuff was silica as well, but it was MUCH more fine than the Quikrete play sand. I'm thinking the really fine stuff is probably my best bet. I've searched and searched and read a million and one opinions on the use of silica sand in a reef tank, but it appears that it will be OK for this purpose. It would have the advantage of not possibly clumping like aragonite can, wouldn't it?
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| Posted 1/16/2006 5:13:56 PM |
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agreed... quiet good for this purpose, and finer the better IMO 
.Anthony Calfo
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| Posted 1/16/2006 11:43:41 PM |
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Anthony,
If I may interject; you may have covered this in the thread linked (I will read it when I have more time) but when running a RDSB it is best to plumb a “T” before going into the container. (This is for RDSB’s that return to the main tank) With a “T” and a couple of ball valves you can shut off access to the DSB should a problem arise. The water will then bypass the refugium and return directly to the main tank.
If the RDSB has become over saturated with nutrients (nutrient sink) you will easily be able to save some pods and worms and discard the sand replacing it with new. The last thing you wish to attempt is to remove a DSB that is still inline with the main tank. Fortunately it usually takes many years for a proper DSB to become over saturated. Prior planning keeps maintenance to a minimum. Ed
I think I'm forming gills...
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| Posted 1/17/2006 9:17:39 AM |
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good point Ed. Having bypasses for this or any filtration component is a very good idea. Some folks will hard plumb their skimmer or Calcium reactor then be confounded some months later when they realize they have to remove it to clean it  Worse still for folks that forget to add slip unions and ball valves to flank water pumps!But the RDSB or any other should never become saturated as defined/decried by the critics. With proper waterflow and (solids) nutrient export at large, there just isn't enough matter to sink and begin to accumulate. And the fine sand (<1mm) in particular does not allow the penetration but rather deflects large solids for them to carry on with currents and stay (properly) in suspension long(er) enough for filter feeders to utilize them or skimmers/filters to simply export or trap them. The reality, again, though is that most folks lack adequate water flow, lack adequate skimmer maintenance, and/or overfeed/overstock. As such... their DSBs really do become burdened over time.
. Anthony Calfo
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| Posted 1/17/2006 6:54:19 PM |
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| Hi Anthony, I read the twelve pages and I think I am convinced that I want to try this. I have been growning chaeto in a diy hob fuge. My questions are what is chaeto using besides nitrates to grow, what impact does its growth have on the corals, is it directly competing for any essential minerals. I can see that a rdsb would be much more efficient at removing nitrate. I have been relatively happy with my chaeto as far as removing nitrate but I have always disliked that it sort of acts like a giant filter pad, trapping particles. Would a 7.5- 8 inch dsb be deep enough. I have calculated that I can get about 45-50 lbs in there. thanks jerry
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| Posted 1/17/2006 8:43:21 PM |
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| if your principal goal is nitrate reduction, then indeed I'd recommend a rdsb over a Chaeto refugium. The former being far more reliable and stable. But the Chaeto does offer other benefits such as its great service as a matrix for growing microcrustaceans to feed corals and fishes. As for paths the nutrients take... its a bit complex but may fairly be stated as dsb=reduction, chaeto=absorption. The former includes processes that alter organic matter that it (theoretically at least  ) can be exported from the system as nitrogen gas, for example. But the latter (absorption) necessarily keeps the nutrients in the system banked as biomass if/until you harvest them... or worse, released with algae decay or die-off.
. Anthony Calfo
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| Posted 1/26/2006 3:04:58 PM |
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| I've got limited space behind my tank but would really like to implement something like this. I was thinking about making a coil denitrator originally. Is there an optimum ratio for depth, width and height or is it jsut the volume of sand? Could I for example run two RSMB's in series made out of 6" diameter and 20" tall piping (equates to 3 gallons)? Gavin
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| Posted 1/26/2006 3:11:20 PM |
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| cheers, Gavin you raise a good point my friend. While I personally have done no formal trials of comparison, I have used a wide range of (shape) RDSBs (again, personally favoring taller barrels or buckets versus long tanks or DSB beds for space savings if nothing else). But I do curently emply four tall tubes of sand in my SW pond (they are employed as bumpers actually in the corners). The tubes are about 6" diameter and 36" tall. I believe they are indeed helping control nitrates as the bioload in that system is the same as the tank the fishes last came from (same fishes) and yet the pond gets less water changes comparatively. Yet the nitrates are under 60ppm (under 40ppm usually) in the pond with RDSB bumbers while the same fishes suffered unreadable (off the chart on test kit) in the previous tank (which had no RDSB). The fishes have grown and they are getting fed more in the pond too. The pond also has about 2" of oolitic sand on the bottom as well, but it shifts about quite a bit from fish activity. Rather aerobic FWIW in the pond.
. Anthony Calfo
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| Posted 1/26/2006 3:16:36 PM |
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| So how about this for a plan. Two RDSB's consisting of 6" diameter pipe and 20" tall - each containing 15" (or so) of sand. Water pumped from the tank into one then daisy chained into the second and back to the tank. Finally... Would there be any reason not to have these as sealed units so that the whole system could be run under slight pressure? Gavin
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