consequences of a shallow sandbed?

[Carpentersreef]

In my system that's almost 2 years old now, I've recently had hair algae outbreaks and it looks like I'm running a friggin planaria (flatworm) farm! I've got a 180g main tank, 50g refugium, 20g sump and about 10g in my skimmer. I've noticed lately (last 6 weeks or so) that my corals have not been as happy as I'm used to seeing them, and I had an area about 24" x 24" that I had about 2 1/2" deep of CC in my main tank and between 1/4" - 3/4" in my refugium. Zero in my sump.
I've tested for everything I have tests for (Ca, Mg, Sr, PH, NO3, NH3, PO4), SG= 1.023 . Everything's within acceptable limits.
I decided last weekend to vacuum the refugium and this weekend to vacuum the main tank because I saw more and more areas of the sand that were turning grey/black at the surface. The stuff that I took out stunk something awful! I can only imagine what it was doing to the water quality, but I don't know what I should have been testing for that I could have identified it.

My guess is that it was Hydrogen sulfide not being processed properly with a DSB. (4" or more) I recently had some advice on this board that 4" was the magic depth for a properly operating sandbed.
After vacuuming all the CC, pretty much overnight all my corals have returned to their previous fully expanded state. Am I correct in thinking that my shallow bed sandbed was the main problem? I'm pretty sure it was, but what should I be testing for to make sure that the levels of "whatever" don't build up like that again? I may be moving in the spring of 2002, so I don't want to start a proper DSB, as it won't have time to properly mature. Should I vacuum the aquarium monthly, until I move?
This morning I changed my 24 x 24 x 2-1/2 sandbed to a 12 x 12 x 5". If there are any DSB experts out there, I would appreciate any comments.

Thanks,
Mitch

 

[davelin315]

I have been using the same substrate (+/- scoops to friends, scoops to start new aquariums, adding a little more depth her and there) since I started keeping corals around 10 years ago. It has never been deeper than maybe 2" (more likely 1"), and I have never vacuumed it. It has never caused me any problems, although I am interested in trying a DSB for a pond I'm building. In any case, I don't think vacuuming it is a good idea, because you'll suck up all your little creatures that live in there. Before the "live sand" hit the market, I had tons and tons of creatures crawling around in my substrate, even though it was very shallow. I have never experienced the problems you have described, despite my lack of a DSB. I don't know if your lack is the problem, but IMO it is not. Not to knock DSB merits, they seem to be excellent ideas, and I am looking forward to trying one in my pond, but it doesn't seem to be a big problem not having one to me (after all, for a long time, people advocated no substrate at all, so who knows if the DSB will last, or if the theories will be modified again, maybe we'll all start using fluidized bed filters some day!).

 

[Carpentersreef]

thanks,
I'm pretty sure that I will remove it now and start a proper dsb (correct grain particles, depth, ect) in the spring. Should I then be vacuuming detritus on a regular basis?

 

[SPC]

Carpenter, as Tom said, I would treat your substrate like an undergravel filter setup, and vacuum it on a regular basis.
Steve

 

[Coraltank]

MickAv8r,Shame on you for not reading the SeaScope Summer 2000 issue.Dr.Ron supplied the hydrogen sulfide info in that issue.Better late than never

.Just a little jibe,no harm intended.

 

[Anonymous]

LOL I think I did read that or read one of Shimek's sandbed articles somewhere that discussed how it could never be at harmful levels in a bed, the "new" information to me at least was that it immediately converted to hydrogen sulfate upon exposure to oxygen.

 

[Anonymous]

Well you had a buildup of detritus. Since you don't have a full normally operating DSB it's hard to say exactly what was going on, however since it is Crushed Coral and the system is 2 years old I would not be suprised if you basically started to suffer from Old Tank Syndrome which often occurs with tanks with UG Filters that aren't regularly cleaned. Your tank may have reacted similarly in that the sand became a nutrient sink but was never fully processed. There likely was not enough life in the sand to process the nutrients properly.

Side tidbit of info I picked up during one of Shimek's sandbed forums this weekend was that Hydrogen Sulfide only exists in anoxic zones in the bed, it immediately converts to Hydrogen Sulfate when exposed to any oxygen and hydrogen sulfate is NOT toxic. Any appreciable hydrogen sulfide would likely make you choke or even kill you and it just isn't produced in enough quantitiy to be a problem in the aquarium.

If I were you I would either remove that current bed and just use a very thin layer of CC or go ahead and start the DSB.

 

[davelin315]

Good thing I have a disclaimer...

 

[JennM]

I have a shallow live sand bed(s) now but in years gone by I had CC, and in the very beginning I had an undergravel. We vaccumed the CC regularly, and cleaned the undergravel periodically and never had "old tank syndrome".

Similarly, now, I vacuum my substrate regularly...every week in my seahorse tank, less so in my reef, and my params are great, livestock healthy and happy one year + later.

FWIW...I don't lose critters. My tanks's substrates are teeming with amphipods and spaghetti worms, and even tiny mysid shrimp in my sump. I've TRIED to vacuum up the mysids, to create a separate culture, and I couldn't catch them

I usually let my waste water stand and settle before I toss it, and I never find substrate "wildlife" in it.

I'm not knocking the DSB...I've never tried it. However, the shallow bed works for me.

The original poster could have had other issues, overfeeding, overaccumulation of detritus and insufficient detritivores, etc., in the bigger picture....

JMHO

Jenn