Is Detritus (Necesarily) a Bad Thing .... ?

[ca1ore]

In my first decade of reefing I thought I was a very bad thing and dedicated myself obsessively to its immediate and complete elimination .... lots of 'active' removal through mechanical filters, homemade socks, etc. In my second decade of reefing I decided to get rid of all the mechanical filters, and while I still felt detritus to be an unwelcome guest, I tended to take a more 'occasional' approach to removal with the use of settling chambers. In my third decade of reefing I have come to the conclusion that perhaps detritus isn't actually a problem (other than aesthetics) and now don't bother to remove it at all ..... and I've never had a more successful tank than the one I have now.

I certainly don't expect most folks to agree, as it runs counter to popular wisdom, but there is something appealing to me in taking a contrarian approach. Indeed the more something comes to consensus, the more I begin to suspect the truth may well lie elsewhere. Water quality parameters on my tank are all excellent. I feed my fish heavily, but also employ significant nutrient export mechanisms (pretty much all of them) except mechanical. I've never had a more productive population of copepods, amphipods, isopods (the small ones) and mysid shrimp - all of which live, as near as I can tell, in and about the settled detritus.

Just my opinion, of course, lacking (as in most cases pertaining to reef tanks) in any scientific rigor. Divergent opinions welcomed ......

[chris_88]

Imo some of the better looking tanks are the ones that get a bit dirty

[ReefKeep66]

The ocean isn't the cleanest place either

[rssjsb]

I think detritus is a natural part of the reef environment and supports diversity by feeding a lot of bottom-of-the-food-chain critters. So it makes sense to me that you're seeing good results in your tank by leaving it alone.

[gone fishin]

The old saying holds true. Everything in moderation.

[Timfish]

I pretty much stopped using mechanical filtration on any kind of regular basis about the same time I stopped using skimmers back around '96 or '97. Interestingly this research has suggested fish poop is an important part of the carbonate cycle: http://www.pnas.org/content/108/10/3865

Here's the first system I set up 17 years ago devoid of skimmer and mechanical filtration and it's still going strong. Notably I've had turkey wing clams successfully reproduce in it. (Ok it was just one baby clam but I'm still going to crow.) http://youtu.be/5AnmQXmE8d0

[Dmorty217]

I'm with you on this one Simon, it's beneficial to corals and other filter feeders and it seems that I have all sorts of life forms thriving in my sump where the detritus settles so I for one just leave it

[rffanat1c]

So where did all of this clean it up and export stuff come from? How do you manage algae?

[jason2459]

I'm all for being lazy. But do take the PaulB approach and periodically create a typhoon. I even picked up a diatom filter to do it with.

[ca1ore]

Originally Posted by rffanat1c

So where did all of this clean it up and export stuff come from? How do you manage algae?

I'm actually not saying that my current approach is THE right approach, only that it may be. Export mechanisms are still critical, because high nitrate and phosphate levels are not conducive to a successful tank. I would always run a big skimmer on my tank, even though there are folks running successful tanks without one. In addition to the skimmer, I run an algal turf scrubber (which seems to have no trouble growing algae), a lighted chaeto refugium, various chemical filter media (that do, unavoidably, act as a mechanical filter - can't have it all I guess) and a RDSB. All are enough to keep nitrates and phosphates at very low levels. I simply have no problems with algae in my display. Although nutrients are low, it certainly would grow there were it given a chance to; but my five tangs and assorted crabs and snails don't give the algae said chance.

I just no longer believe that mechanical filtration plays any positive role at all;,it simply acts to diminish the natural productivity of the tank ...... IMO, of course

[sabo]

I tend to agree that it isn't the bogeyman its led to be. Also think its great for all the small life like mysid and amphipods.

[rwb500]

mechanical filtration does not actually remove detritus. it just sits in the filter sock, foam pad, etc and decomposes from there. so by removing mechanical filtration you are actually increasing the amount of detritus that is removed from your system before it decomposes.

I dont think you will find many people who say that mechanical filtration is necessary in a reef tank.

[ydshim]

I agree with your opinon.

I think that In acuarium, micro & macro-plankton can be living firstly, and then fish & corals.
I think detritus is essential factors in this planktonic environment.
However, excessive detritus can be a problem.
And it seems it would be difficult to properly manage.

[mandarin_goby]

I have detritus in the sump. I never clean it because I don't want to lose pods. My corals look better than ever, my mangroves are growing and I have happy fish, so I'm happy with that.

[Reef Frog]

An interesting topic. Here's an observation based opinion.

Detrius is of course inevitable. I believe it's the foundation of the micro fauna we have in our tanks. I believe it has an important role in sustaining the food web copepods and other life depends on, so it's important for certain fish. It is most likely a valuable medium for certain bacteria which is food for many filter feeders. When I "blow the rocks"' and kick up a storm, I can see a positive feeding response from most corals and believe it's important for filter feeders like coco worms & feather dusters (in fact it may be the key to keeping them long term). Cucumbers, some snails and other inverts depend on it too. So it definately contributes to a diverse and "interesting" aquarium.

However it's my opinion that sometimes you can have too much, especially in a younger, over fed systems that haven't reached an import-export equilibrium yet. When dealing with an outbreak of a pest algae, I believe it helps to starve out the algae by ruthlessly removing detrius from the rock face, where the algae is growing while you are implementing an export mechanism like GFO, ATS, carbon dosing etc. It seems to me that having large amounts of detrius sitting right in the "root zone" of rock bound algae has to play an out sized role in its proliferation, like fertilizer in the root zone of a garden plant. When dealing with GHA & Bryopsis during the first year or two of keeping a salt water tank, I found that keeping it under control was an important tool in solving the problem.

I have read that over time, detrius can "mineralize". Supposedly this is where bacterial action processes and liberates all the organic material, leaving behind inert inorganic junk that no longer can leach nutrients back into the water. I can't remember where I read this or if it's accurate. Maybe somebody knows the answer.

I think it's beneficial to have some detrius present in an mature aquarium which has effective export technology in place, algae eating animals perhaps, a stable & appropriate bio-load and mature live rock with large quantities of anaerobic bacteria that can process nitrates into nitrogen gas. But if for new aquarists battling algae, I think detrius control is an important tool, but certainly not THE most important tool. I can understand why some new reef keepers sweat detrius build up and the old hands don't worry about it much unless it becomes an eyesore.

[Coelli]

For the most part my DT (up for 2.5 months, but was an upgrade so the rock went from tank to tank) has little detritus due to layout and flow; but the small fuge in my sump, ~8g, collects detritus mostly from invert waste. The fuge isn't really meant for nutrient export, it's for additional pod production. Yesterday I cleaned out most of the 1/16" layer of detritus out. The mass of gracilaria was briefly removed. Today I can see that lots of pods and baby pods made it up to the DT in the process (yay!) as I have a bloom in the DT. The dratted hydroids are having a field day.

My question is, how deep should I let this layer get before reducing it? I have 0 nitrates and phosphates and no nuisance algae; I don't mind a little detectable nitrates and phosphate but was worried the detritus would become a problem, but figured it's beneficial for the pods. Any thoughts?

[Reef Frog]

If your nutrient levels are where you want them, have no pest algae issues, everything is healthy and you're happy with the appearance of the display tank, I wouldn't remove it, or just remove enough to keep the quantity somewhat stable. Nothing is broken so no need to fix anything IMO!

[Mishri]

Originally Posted by Timfish

I pretty much stopped using mechanical filtration on any kind of regular basis about the same time I stopped using skimmers back around '96 or '97. Interestingly this research has suggested fish poop is an important part of the carbonate cycle: http://www.pnas.org/content/108/10/3865

Here's the first system I set up 17 years ago devoid of skimmer and mechanical filtration and it's still going strong. Notably I've had turkey wing clams successfully reproduce in it. (Ok it was just one baby clam but I'm still going to crow.) http://youtu.be/5AnmQXmE8d0

Yep, I've ran a power-head only tank before... softies and fish, worked just fine. I also never tested the tank water so I have no idea if i had high nitrates/phosphates, which would be bad for sps.. Only thing I currently run on my tanks is skimmers.

[jason2459]

So, is this the start of the comeback for crushed coral, wet/dry trickle filters, and bio-ball canister filters?

[asylumdown]

In my opinion, detritus is only a problem if you design a tank in such a way as to make it a problem.

case in point - if you have a bare-bottom tank with minimal live rock, tons of flow, and heavy duty mechanical filtration, you've designed a system where detritus is technically a 'problem'. Dealing with it using technology, husbandry, and manual intervention is a central element of the maintenance of that tank, and it's accumulation both risks destabilizing that system, and can be seen as a failure in the system's design somewhere.

If you've designed a system with a sand bed, less mechanical filtration, more rock, heavier feedings, etc., detritus is less central the the over-all functioning of that tank. In that system a much larger cohort of detrital processing organisms will develop, meaning that you're probably not going to see much of what is getting produced until it's well and truly approaching the 'refractory' stage where there's little left in it anything can use. In that tank, keeping an eye on nitrate and phosphate and controlling them using some other method is going to be important, but the detritus itself sort of becomes an irrelevant side-effect.

Good flow will always be important to every tank, but by accident of design my sump's first chamber is essentially a giant settling chamber and in nearly 3 years of not vacuuming once, maybe 1/3 of it has been covered in 1/16 of an inch of 'detritus'. I periodically use filter socks and have a strong skimmer, but I also have a flourishing community of micro-fauna that waxes and wanes according to how often I remember to re-fill the auto-feeder. My sand looks better if I vacuum it every few months, but... what you can still see of my rocks are clean (almost nothing comes off them when I turkey baste), there's almost no algae in the display, and it's packed to the gills with SPS. The rate at which mulm seems to permanently accumulate is very, very, very slow in my system, even though the rate of 'detritus' (however one defines that) production must be very, very, very high.

[reefgeezer]

IMO, lack of detritus should not be the measure of a well designed/maintained system. Flourishing corals and fish over the long term should be the standard.

I bought into the detritus free thing for quite a while. I had no detritus or algae, but the corals were just crappy... little growth, no color, no polyp extension. Better now when detritus is trapped where it can be "used" and nutrients are allowed to rise a little.

[Reef Frog]

^ Yes. Detrius isn't a problem until it's a problem. A little goes a long way. Like so many things in this hobby, it's often best to avoid extremes. A sterile tank can have problems and a tank over flowing with crud is ugly and may feed a nutrient spike that causes an algae Armageddon. The sweet spot is somewhere in the middle. And nobody I've ever met enjoys cleaning filter floss & socks and cleaning the sump.

Good thread. Nice to see all the different experiences and perspectives.

[ca1ore]

Some fascinating points raised! Fully agree if nutrients are out of control, and pest algae proliferating, that measures must be taken and that detritus removal in the short term may be called for. Some nutrient export mechanisms don't need to mature (skimmer, GAC, GFO and water changes) but others do (DSB, Chaeto, ATS), so it may be necessary to do things in the early stages of a tank that become unecessary as it ages. It is also true that even though I use no purposed mechanical filtration, some detritus gets removed via incidental periodic cleaning of reactors.

I would also suggest that there clearly an aesthetic aspect to detritus. I certainly don't want it settling onto my rocks. I want it, but I want it where I want it. Fortunately most well designed aquascapes and adequate in tank flow eliminates this for the most part. Personally I've never subscribed to the bare bottom tank, so no need for me to be overly fussed about some on the bottom.

It's funny, I always remember the freshwater tanks kept by a college professor I knew who had never siphoned his tanks in the decades he'd had them. One contained 6" of mulm on the bottom and I never saw healthier looking fish or plants.

[mussel and hate]

Detritus can be beneficial. In excessive quantities in low flow areas it can be a problem. I've observed deep beds of anaerobic detritus in my BB after perhaps 8 months to one year without a good deep cleaning/vacuum. I've learned I need to do a periodic maintenance where I move every rock and vacuum beneath. The black sulfurous evil thus exported is definitely not benign.

[CuzzA]

I think for the newcomers and less experienced hobbyist it's good advice to keep the level of detritus at a minimum.

For one they simply don't have a grasp on the entire balanced biological processes that are going on in marine tanks. And they are suckers when their fish come begging for food every time they get close to their tank.

Secondly, some of the terms we use can be intimidating. For example, when I first started doing my homework the term reactor sounded like some fancy, crazy contraption.. The only other reactor I ever heard of was Nuclear. Ha, now I could slap one together with some spare pvc I have laying around. Remote deep sand bed... What does it have a clicker? Algae turf scrubber... Is this something that scrubs turf algae? Lol.

Finally, we know how much money this hobby takes to do it successfully, so when the newcomer just laid out $2,000 for the bare essentials the idea of dropping more money into other forms of filtration is often skipped.

So, I think for the seasoned reefer who's learned from his mistakes and has implemented multiple more advanced biological filtration systems that can process nutrients they can benefit from the extra detritus, whereas the new hobbyist has now just managed to grow a tank full of algae with the $2,000 spent. And the first advice they get is remove the detritus from the tank. Which usually is a good place to start.