How did you decide to DSB or not?

[blorkiemom]

Sorry for inventing a verb.

I'm asking this because I'm putting together my first SW tank and I'm just flummoxed over the DSB thing. Every other choice I've had to make as I plan the system has seemed clear to me after some research, but not this one. I've read and read on the subject, and as far as I can tell it all comes down to anecdotal evidence: some people have had crashes that result in terrible losses, others have had DSBs running for years and years with no problems. There don't seem to be any "facts" about why a crash does or doesn't happen, only theories.

Anyway, I've got to decide in the next couple of days. I can't get Southdown, so it's an investment as well as a system parameter.

I don't mean to start another "DSBs are good"/"DSBs are evil" discussion; Lord knows there are many of them already. (Many of which are smart and informative, at least for me.) I guess I'm asking:

How did you, personally, make the decision to go with a DSB or not, and are you happy with your choice so far? If you could throw in how long the tank has been up, that would be great.

Thanks to anyone who takes the time to share. I think it will help not just me but other newbies who migrate over to this forum for additional perspectives.

 

[jaiden]

"answer" from a newbie

Just food for thought, as I'm a newbie and have no experience (though I have read a lot lately)...

From what I've read, DSB problems have to do with

1) wrong depth -- too deep = wrong bacteria

2) disturbing the DSB. Anything which mixes up the sand can either release toxins or just cause the DSB to stop working. Sand sifting fish are a big culprit

3) Not using LIVE sand. Since the bacteria we're looking for need a very LOW oxygen environment (and the ones we're hoping to avoid need NO oxygen) we have to make sure there is a tiny bit of oxygen in the sand. The best way to do this is with a healthy crop of these super tiny sand critters. Starting with plain sand seems to be OK, but it's important that lots of these buggers get in there before the nitrate removal is really needed. Also, these can be eaten by fish and other things, so it's important to monitor the population.

So, I think my solution will be:

2" or so of sand in the tank. This will allow me to have sand sifting fish, but no DSB.

In 6 mo or so, when I can afford a sump setup, I'll partition for a decent sized fuge where I'll have a DSB and maybe macro algae, but no sand sifting creatures.

Just my 2 cents.

 

[HoopsGuru]

How did you, personally, make the decision to go with a DSB or not

I weighed the pros and cons of the various methods and chose one. For me, a plenum was out of the question because the information I reviewed established to me that it was a DSB with the hassle of extra effort to set it up (but no extra benefits). For BB, I chose against it because it requires aggressive skimming and strict siphoning to keep nutrients out of the system. The DSB matched most what I wanted. This could be because I am a firm believer that we can achieve natural filtration in aquariums, even if it doesn't exactly duplicate nature. It was an unknown avenue that was intriguing enough for me to try.

are you happy with your choice so far

Very. Minimal maintenance with acceptable returns (no detectable nitrates, incredible bio-diversity, etc.).

If you could throw in how long the tank has been up

3 years....skimmerless. I keep a 10g tank in the basement with sand and rock into it with no predators. I make it a point to periodically add some of the livesand into the display as well as swapping out pieces of liverock. I believe it helps to maintain strong populations of the necessary infauna. Judging by the fact that I have very little detritus ever even making it to the sandbed, I am satisfied with this approach.

While not trying to enter a debate, I want to put out my own opinions on a few statements.

1) wrong depth -- too deep = wrong bacteria

Just unsure of what is meant and was wondering if a more elaborate answer could be provided.

2) disturbing the DSB. Anything which mixes up the sand can either release toxins or just cause the DSB to stop working. Sand sifting fish are a big culprit

Agreed, sandsifting fish have no business being in a DSB system. They consume the sandbed infauna that keep the cycles moving and turnover the substrate.

2" or so of sand in the tank. This will allow me to have sand sifting fish, but no DSB.

This creates it's own problem. The sandbed will be pretty void of infauna due to the starfish, and thus vacuuming of the sandbed will be required to remove detritus that settles down into the sandbed. Vacuuming of the sandbed will obviously remove sand, and thus periodic additions will be required. In essence, it is like every other system in that it has advantages and disadvantages, but can be equally successful.

 

[jaiden]

more DSB comments

While not trying to enter a debate, I want to put out my own opinions on a few statements.

No worries... I'm not looking to "debate" as I'm still working on setting up my first SW tank! Just repeating some of what I've heard. there was a very long article posted a couple days ago which was apparently VERY well researched, so most of what I know is from that...

1) wrong depth -- too deep = wrong bacteria

Just unsure of what is meant and was wondering if a more elaborate answer could be provided.

From what I understand, a sand bed develops layers of bacteria based on oxygenation. The shallowest layer does nitrification, and has a high oxygen level. Below that in what we call a DSB is where the nitrate to N2 bubbles happens. As you have no nitrate, you must notice these bubbles in a healthy sand bed. If the DSB is too deep, there is another layer underneath that is devoid of oxygen and is therefore full of anerobic bacteria (one of which from what I can tell is the dreaded "cyano-" . A healthy crop of infauna seems to mitigate this, but those that have had DSB crashes seem to report a disturbance in the deeper layers. Lots of infauna probably allow more microcirculation in these lower layers (as does a plenum) which prevents the total lack of O2 which causes bad bacteria growth. I think those with healthy DSB's have this, but may also have picked a depth that helps too.

Agreed, sandsifting fish have no business being in a DSB system. They consume the sandbed infauna that keep the cycles moving and turnover the substrate.

right. the original poster didn't mention a particular desire for these kinds of fish, but they are on MY list. Consequently, I don't want anything too deep. I think keeping my bed under 3" or so should mean that even without a huge population of infauna, I should be safe from cyano, and still get some benefits of nitrification and maybe a little n2 export. Regardless, for me it doesn't matter (from what I can tell so far) if I have nitrates, as I won't be running any corals with this setup. As I've mentioned, I'd like to add a sump/fuge with a proper DSB, but this is at least a few months out.

This creates it's own problem. The sandbed will be pretty void of infauna due to the starfish, and thus vacuuming of the sandbed will be required to remove detritus that settles down into the sandbed. Vacuuming of the sandbed will obviously remove sand, and thus periodic additions will be required. In essence, it is like every other system in that it has advantages and disadvantages, but can be equally successful.

True, I'll probably have to replenish more often than I'd like. I'm hoping that with good circulation, the LR will take care of most of it. I want to avoid vacuuming if possible.

 

[blorkiemom]

Thanks for responding. Since I didn't get too many bites on this, I sucked it up and went to the LFS to get 180 lbs of sand. After measuring it out, scoop by scoop, the clerk informs me they only have 90 lbs in stock. Just enough for a 2" bed. I'm trying to decide if this is a sign from Neptune to go SSB . . .

Anyway, I guess I'll just go for it and pick up 90 more lbs. If I start to have problems in 3 years, well, I'll have three years' worth of experience to help me deal.

Can't someone just tell me what to do? It's so hard to make an unclear choice. --which is why I'll never be President, I guess.