Forums / Marine Systems and Husbandry – by Anthony Calfo / Archived Forums / remote dsb / Latest Posts

RE: remote dsb

Anthony Calfo — Wed, 12 Mar 2008 19:58:08 GMT

erock... please refresh/inform us about the tanks situation and history:

bioload, tank age, water change schedule, nitrates before RDSB, etc

RE: remote dsb

Anthony Calfo — Wed, 12 Mar 2008 19:55:54 GMT

the mechanically (and chemically in this case) prefiltered water is quite ideal for a RDSB. No worries

RE: remote dsb

risin — Wed, 12 Mar 2008 14:49:27 GMT

First off, I have read this entire thread and I read the first 10 pages on the RC thread before I lost connection to their forums. It's a great read and I plan to finish but I have a couple questions that I did not come across answers to so... hopefully this isn't a repeat question.

It would be really convenient for me to run the RDSB off of a specific pump in my sump. The only problem is that the water from the pump runs though a filter sock, protien skimmer, Purigen (resin/carbon substitute), and a UV sterilizer (UV lit 14 hours a day) before it would make it to the RDSB. Would that be an issue?

RE: remote dsb

erock — Tue, 04 Mar 2008 11:46:58 GMT

Update: 4 weeks in, no change in NO3.

RE: remote dsb

Anthony Calfo — Mon, 25 Feb 2008 09:22:27 GMT

your question is loaded/generic, my friend. Yes.. there are possibilities. But rare. Its really hard to screw up an unlit bucket of sand. As long as there is a steady stream of water flowing across it to prevent solid matter from accumulating (or better... mechanically prefiltered water), then you will not likely experience any problems indefinitely. Nothing but good nitrate reduction to be had and some dissolution of sand (if using aragonite) for a lil mineral contribution to the system.

RE: remote dsb

erock — Sat, 23 Feb 2008 11:11:49 GMT

Anthony, are there any reasons that a properly setup RDSB wouldn't work?

RE: remote dsb

Apos — Thu, 21 Feb 2008 21:45:04 GMT

I was able to fit the powerhead in my middle sump chamber, the one with a constant height and my protein skimmer in it. Not sure how I'd get an overflow unless the output clogged:if the pump fails, the remaining water difference in the bucket should just drain into the sump, with plenty of room to spare. If the output clogs... well... not sure what else I could do on that, other than having another output higher up as a backup (but then the lid wouldn't fit on)

I actually documented the whole thing here, with pics, in case anyone is interested:
http://www.saltwaterfish.com/vb/showthread.php?t=305309

RE: remote dsb

Anthony Calfo — Wed, 20 Feb 2008 20:06:06 GMT

gurgling is from air or more commonly from being overdriven (too much water flow for path/holes).

"powerhead and overflow tubes in and out of the final chamber of my sump"

can you provide some kind of sketch or drawing. I am very concerned about the above statement. I see a flooded floor and possibly loss of livestock in your future, my friend.

RE: remote dsb

Apos — Wed, 13 Feb 2008 21:25:30 GMT

Everything is set up and running. I have a DIY thread about it with pictures and step by step description of how I put it together over on SWF.com (not sure if I can link to other boards, so I won't).

Now I wait four weeks or so and see if it helps any.

RE: remote dsb

IPT — Wed, 13 Feb 2008 14:59:17 GMT

I think using the airline is just a way to allow the pipe to get air without interupting the water flow which causes the purge/gurgle. I have used it on standpipes too. Just slip it into the pipe a little at a time. When it is at the right place it'll draw the air in and should quiet it some.

RE: remote dsb

Apos — Sun, 10 Feb 2008 20:41:21 GMT

Everything is set up, and the bucket is running out of and into another bucket, ready to hook up to my system. Onyl problem now is gurgling: I have the input higher than the output, and the output is 3/4inch pipe whereas the input is 1/2inch. But the output is gurgling and glugging something awful. I've read that people "put airline" in the output and this somehow stopped the gurgling, but I don't get exactly what was done.

RE: remote dsb

eeorrandy — Thu, 07 Feb 2008 14:36:07 GMT

I've always prefilled the rdsb with fresh saltwater prior to turning the pump on, but mainly to keep the ATO from kicking on.. Also I use a filter sock after the rdsb for just a day or two to catch any particulates going through, the dust settles pretty quickly though.. no worries.

Randy

RE: remote dsb

Apos — Wed, 06 Feb 2008 22:50:31 GMT

I've got most of my materials together. I'm going to screen my sand just in case someone dropped a screw into it, but I'm not sure about washing it. I have fine silica sand, the Quickcrete brand (for sandboxes, says washed, screened, dried, etc.), and some (pricey!) aragonite to give the system a bit of buffering oomph.

I know that rinsing will rid the sand of some of its best fine particles/surfaces. But what I don't want is a cloud of fine particulate dust being pumped into my tank, or any too concentrated industrial contaminant. What's the best way to rinse this stuff off before hooking it up? And should I fill the sand bucket with fresh salt water to begin with before hooking it up to the pump (sort of the way you fill a filter pump up instead of starting it dry)?

RE: remote dsb

erock — Tue, 05 Feb 2008 07:51:52 GMT

The RDSB only took me like and hour and a half, it was the moving around stuff, building up a stand, waiting for my drill battery to charge and of course the multiple trips to the hardware store for parts.

RE: remote dsb

Apos — Mon, 04 Feb 2008 20:01:32 GMT

One thing I'd not considered yet: I'm going to need to put the powerhead and overflow tubes in and out of the final chamber of my sump (the one with the return pump in it). If, as most people seem to have done and I was planning on doing, I make the drain pipe bigger than the input (and slightly lower on the bucket) to avoid any chance of an overflow, I might get bubbles going into my return section, no? I don't have room for any more baffles: not even a rudimentary bubble trap, unless there is some alternative (some kind of nested pvc setup around the drain?). Is there any way to pump the overflow output pipe to avoid dropping bubbles into my sump, and then pumped right out into my DT?

RE: remote dsb

Anthony Calfo — Mon, 04 Feb 2008 14:56:24 GMT

erock... no worries about the extra water above the sand. No harm indeed. Just a slight expense to sand that could be denitrifying.

I'm curious to know why it took you 7 hours to install, though?

Apos... good tip bro. The taller bucket for many may allow some installs to have the bucket sit next to the tank without propping it up to overflow into the sump.

kind regads to all,

Anth-

RE: remote dsb

Apos — Sat, 02 Feb 2008 22:56:11 GMT

5 gal buckets tend to be a pretty standard height, but its worth noting that 6 gallon buckets are available, and generally still fit under a 55gal stand or bigger. I'm going to be setting up a RDSB this week, and I'm using a 6gal bucket from Dick's sporting goods. Some fish stores sell them as water change buckets, and they are of course available online (but who wants to ship a bucket?) Major stores like Lowes and Home Deport, unfortunately, spend too much time pimpin' their branded buckets to offer any kind of selection.

Anyway, I needed a 6 gal to more easily overflow into my tall sump, and hopefully it should give me another inch or two worth of sand as well. I wish they sold buckets with ribbing in more convenient places for adding bulkheads though...

RE: remote dsb

erock — Sat, 02 Feb 2008 19:49:36 GMT

Ahhh, well that was about 7 hours of pure enjoyment, but it's up and running. How critical is the amount of water above the sand? I'm at about 4-5" right now.

Pray for now power outages or i'm going to have a real mess. With the addition of the RDSB, i've exceeded the limit my sump can hold from everything draining back into it. Time to put on the thinking cap.

RE: remote dsb

erock — Fri, 01 Feb 2008 18:52:09 GMT

I picked up 250 lbs. of playsand today (small grain, probably silica) but that needs to thaw out, there solid bricks of sand at the moment. Hoping to get this up and running by next weekend.

RE: remote dsb

Anthony Calfo — Thu, 31 Jan 2008 21:12:48 GMT

no problems with an oversized vessel at all... the more the better (for buffering if nothing else). The denitrifying faculty will only grow ti the load put upon it. So an oversized one will be fine but an undersized one will be limiting.

RE: remote dsb

erock — Thu, 31 Jan 2008 10:40:27 GMT

Thanks Anthony. This is the vessel I plan on using, and if this works well on this tank, I would use the same vessel on the 300 with plenty of room to spare. Any problem with having an oversized container like this? (Mainly empty space above RDSB)

Where you see the waterline is at about the 25gal. mark in the vessel.

RE: remote dsb

Anthony Calfo — Thu, 31 Jan 2008 09:39:36 GMT

cheers, erock

rolling with the ballpark estimates here... I'd recommend a bare minimum of 100lbs of sand for an RDSB on this system with a typical (lighter) bioload.

To hedge bets and considering your heavy bioload though, I'd suggest doubling that. It amounts to a volumetric 20-30 gallon vessel. You can find small food (pickle, olive, etc) barrels plastic and sturdy from the local food market (find your hometown district that sells wholesale foods tot he restaurants and there you will find such barrels cheap or free from the weekly imports). Else just make sure you have a sturdy plastic container (see those used throughout the threads on RDSB).

Without knowing how much nitrate you have... its tough to say. But I'd suggest that you do a large (50% minimum) water change on your system about a week after you get the RDSB online. After a couple of months (again... depending on how high you were to start and how big of a water change to you did to reduce the initial levels) Id expect you would see a BIG reduction and continued maintenance of lower nitrates from the RDSB (without needing large water changes... though hoping you are good about doing them in general: Dilution is the Solution to Pollution )

RE: remote dsb

erock — Wed, 30 Jan 2008 19:32:36 GMT

Greetings Mr. Anthony, I would like to set up a RDSB and I think i've got it figured out as far as a vessel and amount of sand, but could use your reassurance that my figures are correct before I get started.

Total system volume is approx. 240gal. System consists of a 140gal. cube, 60gal. cube and 40gal. sump approx. 3/4 full. Filtration consists of LR (not sure how many pounds anymore) and a small (10gal. refugium with chaetomorpha). SSB's are in both tanks as well as the refugium. Also, a NW200 skimmer.

I would say this system is heavily stocked by most standards. I could give you a total fish list, but that would require you to visit your favorite beverage-mart and pick up some of your favorite reading beverages. Trust me, it's heavily stocked, but all fish are healthy and happy. (300 gal. tank isn't too far off) Nitrates in this system are pegging out the Salifert NO3 kit and 100+ NO3.

I have a 65gal. vertical stock tank which I got from menards. Overall height is 41" and footprint is 24" round. I was figuring I would need approx. 25-30gal. volume of sand with just 2"-3" of water on top of that. Does this sound like a good amount? That would give me a sand depth of 15"-18".

Also, know where I can order curved bulkheads?

Thanks for your time!

RE: remote dsb

ReefArtist — Wed, 23 Jan 2008 03:09:32 GMT

I have to agree - this is very interesting. The finer details of how our systems work (or don't in some cases) is what I've been missing. I've always been told not to use the play sand or such - but now I know I can but also it's limitations. This is wonderful information!

RE: remote dsb

Anthony Calfo — Mon, 21 Jan 2008 10:19:19 GMT

wow...interesting, my friend. And I'm wondering if you need to wash it at all. If its anything like the oolitic aragonite US aquarists use... its a mistake to wash it (fine particles dissolve faster and are more early side buffer support).

The trick is to just soak the sand first (fresh or salt water) before using it. A few days is usually all thats needed in a bucket. I fill smaller (easy to lift) bags and set them in buckets to soak for adding to established tanks. No clouding of the water then at all.

RE: remote dsb

Tone — Sun, 20 Jan 2008 18:44:39 GMT

Anthony Calfo (1/15/2008)

Marcus... thank you for your kind words about my book, my friend. I have been AMAZED at the support and number of purchases from Australia! I have watched your hobby market grow by leaps and bounds in the last decade. Kudos to the Aussies!

Re: silica sand... no worries at all. It is of very little consequence to use silica (very little hard indeed). There are only RARE exceptions of species that cannot thrive on sharp versus oolitic grains and those exceptions are far fewer than the dreadfully common and far worse keeping of freeliving corals on hard substrates as too many folks do with Trachyphyllia, Catalaphyllia, etc.

If your RDSB is true (remote, not in the display) silica sand will be no problem to use my friend.

Anthony, there's a few of us here in Oz who use calcium cattle feed supplement ... in fine granular form. It has perfect grain size and is seems to be great for buffering, not to mention its brilliant whiteness. I did my entire mega-tank set-up incl both RDSB and DSB with this product and it has proven to be a winner ... it just needs a good wash to get the dust out of it.

Tone

RE: remote dsb

Anthony Calfo — Fri, 18 Jan 2008 09:25:47 GMT

Thank you, my friend... I'm very glad you like the book. It was a bit of a rough road illustrating it and changing the format (an extra two years work in design, collecting photos, rewriting/editing, etc)... but I must say that my normal self-critical self is content with this edition (though I have already started collecting new/more pics to improve the next reprint :p)

Regarding the silica sand... nope: no worriers. The is no more significant "leaching" of silica from the sand than there is from the panes of your aquarium. It is simply an issue of shape:

Oolitic aragonite is spherical by (namesake) definition. As such, it is very fluid as a bed. Diatoms and other algae that grow on it are often quickly tilled into the moving sand. But Silica is "sharp" (angular) in shape and as such locks/packs and does not move much at all. As such... algae can establish more easily on it.

In an unlit RDSB... it is a moot point. No worries about silica sand at all.

RE: remote dsb

ReefArtist — Fri, 18 Jan 2008 02:48:29 GMT

Anthony Calfo

Thank you very much for taking the time to respond to our questions. Clarifications are always good when our livestock are at risk. With my new changes (splitting the 75g and making water flow OVER this area) I’m hoping for “0” nitrates for the life of this system.

I do have a question about silica sand: I thought the reason it wasn’t wise to use in our reef tanks was because of the “silica” as it promotes algae growth, am I wrong in this thinking? I would think the only reason it might be supported in its use would be the small amount used for RDSB. With water flowing over this area it would not contribute to higher silica levels. I could be way off base in my theory, so please correct me.

I also must add – your new book “Book of Coral Propagation” volume 1 edition 2 is absolutely wonderful. It is most definitely my number one book, not only for coral propagation but as a reference for general reefing – I can’t say enough. Thank you for the nice signature – that was a very nice touch .

Thank you,

Carol

PS – I must include (I forgot in my first post) my build thread is on RC within the larger tank section. Here's the link:

http://reefcentral.com/forums/showthread.php?s=&threadid=1145853

RE: remote dsb

Anthony Calfo — Tue, 15 Jan 2008 14:13:47 GMT

cmoresps - I may be presuming too much, but I think this article may summarize your questions about DSB when/where from my perspective:

http://forum.marinedepot.com/Topic59558-13-1.aspx

to all... you will find the above and much more under "articles" and "discussions" (especially the latter post in this thread):

http://forum.marinedepot.com/Topic19836-13-1.aspx

Carol... so sorry not to visit your thread yet but personal time has been at a rare premium for me. My forum visits have dropped dramatically due to increased work/family time needed. Re: your RDSB... the size is adequate indeed, but flow through is bad. Flow over is good Did you mean the latter?

Marcus... thank you for your kind words about my book, my friend. I have been AMAZED at the support and number of purchases from Australia! I have watched your hobby market grow by leaps and bounds in the last decade. Kudos to the Aussies!

Re: silica sand... no worries at all. It is of very little consequence to use silica (very little hard indeed). There are only RARE exceptions of species that cannot thrive on sharp versus oolitic grains and those exceptions are far fewer than the dreadfully common and far worse keeping of freeliving corals on hard substrates as too many folks do with Trachyphyllia, Catalaphyllia, etc.

If your RDSB is true (remote, not in the display) silica sand will be no problem to use my friend.

RE: remote dsb

Mxett — Sun, 13 Jan 2008 16:09:29 GMT

Hi Anthony.

I am currently upgrading my system to a 4 x 4 x 2 and I plan to incorporate a rdsb in a 65 litre crate. I have heard some people say that I should not use silica sand because it is essentially sharp shards of glass and will damage the gastrointestinal tracts of any invertebrate that ingests it.

For cost reasons, and to get the fine size I need, silica seems like a good option, especially since fine aragonite sand would be difficult to find and very expensive.

I would appreciate your thoughts.

Regards

Marcus.

PS your new book is making waves over here in Australia.Well done!

RE: remote dsb

ReefArtist — Fri, 28 Dec 2007 06:00:30 GMT

I also wanted to add to this post (couldn't edit ) I also have a 30g Sea Horse tank and a 30 - 40g Infinity (Flows over edge) tank attached to this system. I have a 29g QT that is not part of the water system except for RO/DI fresh saltwater for water changes and waste water connection.

Thank you!

Carol

RE: remote dsb

ReefArtist — Fri, 28 Dec 2007 04:08:49 GMT

Hello,

I have a question about my current build – here’s my current setup and a link to my build thread:

http://reefcentral.com/forums/showthread.php?s=&threadid=1145853

280g display (built in wall – 1/2 in 1/2 out) 72”L x 36”D x 25”H (2 – 3” sand bed)

(2) 6200 Tunze Pumps

(2) Barracuda Pumps (Return)

20g Frag tank (SPS Only – no sand)

10g Gorgonian (Non-Photo – no sand) tank (After reading your new book - I decided this would be the best setup for these beautiful coral)

90g Sump with 4 baffles – no sand (Live rock in the middle)

40g Grasses/Refugium tank – (5” - “0” grade sand)

75g Not sure – I have 10” – “0” grade sand at the present time)

Reeflo Protein Skimmer

Ozone with a Ozone Reactor going into Carbon Reactor

My question is the 75g tank I have. I was originally going to make it strictly a refugium but the more I read about RDSB’s the more I was convinced that is what I needed. After reading the size requirements I believe the 75g is way overkill for a RDSB for the size of tank I have. Now my thinking has lead me to splitting the tank with a baffle (lack of a better word) and have the water flow through the RDSB (1/2 of the 75g – filling it with “0” grade sand to 3-4” of the top of my water mark), the water then would flow to the other side of the tank which would be a refugium. How does this sound - or would it be better to have the refugium first? It seems from everything I’ve read, a 35g container would be enough to handle any nitrate problems I would develop (I have high nitrates now in my old 65g). Not positive and before I make any changes would love some feedback from the expert.

If it’s not too much trouble (I know you’re a busy man – with your new book and magazine), I’d also love for you to say hello to everyone on my build thread – they have been great and we all would love for you to drop us a note.

Thank you – you are wonderful for our hobby!

Carol

RE: remote dsb

cmoresps — Sat, 15 Dec 2007 19:30:02 GMT

Anthony,

two last things worth noting: I use two sequence hammerheads so this system has tremendous flow and turns over a gazillion times per hour, also, instead o using 100% arragonite sand in the rDSB buckets home depot carries pavestone playsand a very fine silica sand which I intend to use in the lower 2/3s of the rDSBs.

Thanks again

RE: remote dsb

cmoresps — Sat, 15 Dec 2007 19:18:11 GMT

Thanks Anthony,

I am actually trying to run a sps farm so to speak. I have many years experience with sps, so I am quite familiar with the ins and outs of bugs, importing, ect, but in the past I ran everything on a dsb. Long story short, I ran into a crash (root cause was a bad pump, long story). So when I decided to set back up I thought I would go with a dsb but you cant buy sugar grain aragonite cheap anymore, so I went with what I could get which said oolitic on the bag, little did I know it wasnt deep enough (yep that was a big mistake!).

System is a 160 with a dsb (thats the dsb thats bad), 5 tangs, plenty of rock although when I re did the sand bed I used pvc frames to minimize liverock sand contact, allowing for a more open bed. This is hooked in with a 200 gal sump, pulling on the sump is a 50 gal flat rubbermade with dsb (sand 6 inches set up a month) has nassarius but after reading I am switching to cerith, and I use cheato. Also connected to the sump are 2 300 gal prop tanks, each with 3 fish (tangs and wrasses) and plenty of rock, bare bottom though (I have nassarius and other snails present, I set up a small container for sand as I read nassarius like to sleep under sand although that maybe bad info). I have plenty of skimmers, run ozone, kalk stirer, all the good stuff.

Coral wise I have about 100 colonies and countless frags growing, a few zos and maybe 5 lps colonies. This system is hardcore sps and I just wanted to set it up as bulletproof as possible and yet maximize growth and health (hence why I ordered your book!) One thing I noticed in my experience is that for whatever reason (perhaps its organic phosphate), sps seems to grow faster in systems with satellite dsbs/refugiums vs systems with large dsbs [maybe I have been smoking too much of something but I have seen this in many different tanks). This is also why I am very interested in setting up a few rDSB buckets or a rDSB trashcan and yanking the main DSB, the system would still have the refugium DSB.

Any advice is much appreciated!

RE: remote dsb

Anthony Calfo — Sat, 15 Dec 2007 16:52:24 GMT

As much as a love using RDSBs for my systems... they are not for everyone. IN the most recent DSB article here on MD (in the article section under the Fav links sticky) I give the crash course:

short story: your aquarium needs to have a focus for best success. If that focus is predominantly sps corals, then a DSB is likely not for you.

Please tell us more specifically about your fish and coral bioload (numbers and species/sizes) to better help you.

kindly, Anth-

RE: remote dsb

cmoresps — Wed, 12 Dec 2007 20:59:52 GMT

Anthony, first and foremost thanks for all of your research and your willingness to help those in need with answers

Just a quick question, WWACD? lol

Seriously here is my dilemma. I have read all of the killer threads on DSBs and DSB buckets. I have a large sps system (1000 gal system). My DSB in my display developed anaerobiosis from lack of depth compared to grain size (the bags of sand said oolitic but they were not sugar and that was my bad). Certain sps pieces decolored from stress (no bugs), despite trate, trite, ammonia, phosphate readings of 0. Cyano started to break out in the tank with the DSB, so I suctioned out a small portion of bad sand (I test suctioned to see where the heaviest black portions were), replaced and put another 1-2 inches of sugar size on top. I set up a remote refugium with chaeto, and started running ozone. Things are definately better, but I am still seeing black layers of sand expanding in the DSB through the glass. I ran across the thread on DSB buckets and am truely fascinated.

I am now thinking it would be in my best interested to fix this once and for all by setting up 2 29 gal rDSBs, (1/2play sand 1/2 sugar sand on top) leave the refugium in play (it’s a month old), but take the display offline, remove the DSB and go with a dusting in the display. My only concern in removing the big dsb is a rise in trates but I have a 200mg ozonizer with a controller, with a light load of fish. From what I am reading in the threads, the refugium definately has benefits, but the rdsbs would provide additional stability. In the end would you recommend removing the DSB now at the same time I set up the rDSBs or should I wait a few weeks after the rDSBs are up? If you recommend waiting a few weeks on removing the DSB, should I cut back on ozone and skimming to help “charge up” so to speak the rDSBs? I am sure the answer lies in your new book, which I have ordered, but am anxious to know what you think.

Thanks

RE: remote dsb

Anthony Calfo — Sat, 08 Dec 2007 14:06:50 GMT

thanks for the kind words my friend Indeed, the books (especially the Reef Invertebrates (2003)) have far more extensive refugium info than we can cover in a scant few posts.

Re: depth... much beyond 12" deep RDSBs on home-sized aquaria is more than needed. The half-life so to speak (rate of dissolution) in typical applications is around 18-24 months. And while denitrification can occur in beds less than 1" deep, its my opinion that it far easier if not better (more efficient) in beds over 3" deep (more if grain size is over 2mm). As such, an 11" bed will allow you to go solidly four years without having to add more sand, likely. Of course, it depends on bioload and other aspects of husbandry too... but I/we are presuming average and adequate params.

Upstream refugia have a slight advantage (water polishing, less plankton shear... although overrated as a concern, etc) nover downstream ones... and please do heat it to the same temp as the main display (76-82F)

For seeding... yes, it helps to introduce some wild live sand or live rock if you are trying to grow worms, pods, etc... but then again, they will likely come from the inline live rock of your display. And if you just want efficient NNR (natural nitrate reduction) without the baggage of a lit refugia, need for bioturbation, etc... then starting with dry sand only in an unlit RDSB is a very safe way to go and get simplified nitrate control.

RE: remote dsb

snorvich — Fri, 07 Dec 2007 18:29:24 GMT

And one final question. Should I warm up the water before sending it to the RDSB. Tank temperature is 79 F.

RE: remote dsb

snorvich — Fri, 07 Dec 2007 18:26:56 GMT

Well, I read the reef central thread, this thread, but more importantly I am reading your (Mr. Calfo's) two books. The books are incredible and highly recommended. Anyway, I have two largish (350 gallon) systems on the first floor and a fish room in the basement. Water comes down to a skimmer (Bubble King) chamber then is chilled or heated and sent to a phosphate reactor, then carbon then to the second section of my sump. Some water now goes to an ozone reactor then carbon then back and some water goes to a 42 gallon refugium with an aiptasia section, a chaeto section and a benethic section and then goes to a remote deep sand bed. This RDSB is a 14 gallon container with sugar fine sand then water goes back to the sump then up to the aquarium. Flow through the refugium and thus through the deep sand bed is about 300 gallons per hour. The RDSB has a top on it so it is essentially dark. My questions are: at what point do I run a risk as the argonite sand dissolves where I would have to add sand back (probably a couple of years, but what depth?) AND is there a point of diminishing returns on sand depth (currently about 11 inches but I could increase to 14-16 inches). When I do add additional sand, is there a preferred way to do so?

RE: remote dsb

bart — Fri, 23 Nov 2007 13:57:33 GMT

tried to edit but can't. I did not mean critters as much as I understand bacteria is going to grow. But to use brand new sand vs live sand...

Bart