Detritus in a reef tank

[biom]

I have 3 years old, 77 gal bare bottom mixed reef and I'm siphoning out build up detritus every week, last week i decide to measure how much detritus I can collect for two weeks. I'm feeding with 10 grams frozen food daily, and carbon dosing 10 ml daily, two part ca/alk dosing, oversized skimmer skimming wet. My live rocks are on pvc stand to prevent detritus to be deposited and small tunze pump creating flow under the rocks. In this manner all the detritus is collected in small area in one of the corners of the tank.

So I was surprised how much detritus is build up for two weeks! It was more than 120 ml. And I decide to dry it and weight it - 48 grams dry weight! That surprise me and I decide to measure how much food i'm introducing in my thank, so I've dried 10 grams frozen food - and it was only 0.63 grams after drying, so for 14 days i've added only 8.8 grams dry food, but the detritus build up for this period was 48 grams! I assumed that there is calcium carbonate in detritus so I've added citric acid to dissolve it. It was funny of course because adding acid to a cup of crap containing calcium carbonate is always funny and smelly after plenty of citric acid, and measuring pH, reaction stopped and I've rinsed all the remaining stuff with plenty of RO/DI water to flash out calcium citrate. Dried again and it was only 23 grams, i.e. almost 50% of the detritus is calcium carbonate, but still 23 grams is organic, and I've added only 8.8 grams food, and not to forget - my skimmer was running wet all the time.

The only reason for me is that live rocks are leaching some organics that is build up during this 3 years, because my system is bare bottom with this type of circulation and detritus siphoning from about 6-7 months.
This results convince me that siphoning out detritus is very important for healthy system, because there is no way 23 grams dry weigh of detritus to be removed by a skimmer for 14 days or to be degraded by bacteria to NO3, CO2 etc.

This results are pretty interesting to me and i'm planning to do this regularly to see if there will be trend in detritus amount with time. And I will post it here, if you are interested of course.

_____
Stoyan Mihov

 

[Randy Holmes-Farley]

Interesting experiment. Thanks for posting it.

You might compare the results to this data for skimmate, which looks similar to your results:

http://www.advancedaquarist.com/2010/2/aafeature

FWIW, I'll bet there's significant silica in your detritus from diatoms. Probably a lot of live bacteria and diatoms as well.

 

[biom]

Thank you Randy, for bringing my attention to this article, very interesting, I'm glad to find that there are very close results about calcium carbonate concentration, but i doubt if organic silica in my case could be 11% or circa 5 grams - that is quite big amount of silica collected for 14 days, my RO?DI unit shows 000 TDS, there were no water changes during this period, and I dont think my Pucani and Fiji live rocks could leach 5 grams of silica in 14 days. But even if we assumed that only 34% of detritus is organic that means 16.3 grams in my case still two folds more than food i've added during this two weeks.
Next time I'll take into account skimmate too.

 

[Cleo642]

You are measuring poo? Lol, I am sorry, I just had to say it.

 

[Cory]

Thanks a lot, nice info!!

 

[biom]

You are measuring poo? Lol, I am sorry, I just had to say it.

I'm an ecologist and I'm measuring humans "poo" spread over the planet, so I feel pretty comfortable with just fish natural poo .

Thanks a lot, nice info!!

Thanks, Cory. I'll try to take simple "picture"of the nutrient balance in a artificial closed system like reef tank, what's in, what's out.

 

[JohnnyTabasco]

GREAT thread. Have you figured out any thing new since?
I'm trying to not remove Detritus from my system at all. Haven't seen any negative results yet.
Maybe it's a misconception that it's a bad thing?

 

[maroun.c]

I didn't go into measuring the amount of detritus my setup is producing/accumulating... but a while back my external skimmer pump broke and I had to place an internal skimmer as a temp solution while waiting for spare parts. the 1st partition of my sump has around KG of LR with around 20K litres per hour effective flow. I had seen some Detritus accumulation under the rocks so before taking them out I dropped the water level in the sump to isolate that partition and then took the LR out. I rinsed that partition and syphoned it to the bottom 3 times and it would colour up black again on refill with a crazy sulphide smell. then I scooped all the sludge and accumulating detritus and rinsed twice again to get clear water and refilled and placed skimmer. I still can't imagine how this much detritus accumulated in sucha moving partition.

 

[CastAway]

Following....

 

[jason2459]

GREAT thread. Have you figured out any thing new since?
I'm trying to not remove Detritus from my system at all. Haven't seen any negative results yet.
Maybe it's a misconception that it's a bad thing?

I find detritus to be beneficial to biodiversity. I don't worry about.

I do periodically create a typhoon in my tank with a diatom filter like once a year which I took from PaulB.

Otherwise I find all sorts of life making detritus food and home.
https://www.reef2reef.com/threads/our-tanks-biology-up-close.239838/

 

[JohnnyTabasco]

A diatom filter.... what's that?

 

[SaltEverywhere]

It's hard to imagine removing more biological material than you are adding without eventually watching fish shrink and your rocks and sand get less dense. Could the extra detritus be due to contributions from the photosynthesizing community using CO2 to produce mass?

 

[jason2459]

A diatom filter.... what's that?

A filter that uses diatomaceous earth (DE) powder to coat a filter bag which will then filter down to 1 micron.

This is the filter I have
http://www.diatomfilter.com/products/diatom_xl_filter.htm

I bought a really big bag of DE powder from a pool supply store a long time ago. It will last me an extremely long time. I filled up 2 5 gallon buckets for easier storage. If I remember right there was some left over still that I used up first.

 

[Randy Holmes-Farley]

A diatom filter.... what's that?

It is a packed sand-like materia (the dead diatom skeletons) that filters particulates as the water passes through it.

 

[atoll]

Thought I would resurrect this thread as I find the whole question of detritus in reef aquaria interesting. My own 100gallon is 18months old and apart from protein skimming I have no other form of mechanical filtration.
What I find interesting and ponder is just how detrimental the build up of detritus is to our reef animals releasing vast amounts of nutrients as we are constantly told. However, I have never seen any scientific evidence supporting these claims. I am not saying what we are told isn't true just to what extent does detritus release these nutrients which are claimed for all manner of nasty things.
We already know detritus is a valuable food source for many corals which is a good thing and I blast my sand regularly to release at least some of it into the water column. However what I would like to know is just how much PO4 etc dose detritus release and does it at some point become more or less inert with time. So I guess I am really asking is detritus the enemy we are constantly being told it is as I remain to be convinced it is?

 

[Nano sapiens]

So I guess I am really asking is detritus the enemy we are constantly being told it is as I remain to be convinced it is?

I also have a keen interest in how detritus effects our systems, but I have found very little in the way of scientific investigation regarding the effects of detritus in a closed reef system. The Reef Aquarium series by Delbeek/Sprung has some of the best information on the topic that I have read so far. But I have read some scientific papers regarding the fate of detritus in the wild (much of the marine snow ends up sinking into the abyssal depths and VERY slowly gets recycled via plate tectonics). This, of course, has little direct bearing on our artificial systems, but does show that much of the detritus is exported away from the reef itself.

*(my 2 cents): I think it helps to look at this question from the nano aquarium angle. Due to the (typically) small volume of water in relation to the live rock/bio mass, detritus build up happens much more quickly. Many years ago the prevailing thought (perhaps adopted from the DSB 'Don't touch the sand bed' philosophy), was to leave the sand bed/detritus undisturbed. In the nano systems, severe issues were typically encountered ~8 months to ~2 years after setup (time dependent on various factors). Complete system failures were rather common, unfortunately, and a lot of reef keepers would just start all over again (or quit completely). Looking at the large number of today's nano tank examples where a good portion of the detritus is removed regularly (not necessarily all detritus), they tend to be healthy and can last for a decade (or more) with proper care.

In much larger systems with no active detritus export, heavy detritus build up is typically much slower (measured in years, or even a decade or more). While organics in the detritus being released can be a factor if it hasn't been rendered nearly inert by the microfauna, I believe that the physical effect of large amounts of detritus in a sand bed/live rock is likely more detrimental as it can cause near stagnant conditions for the aerobic/anoxic/anaerobic bacteria (microfauna, if present in sufficient numbers, would undoubtedly help here, but in most medium sized systems that is not the case). As such, the various bacteria in our systems are deprived of oxygen (in the case of aerobic) and nutritive substances that would normally be delivered via advection, and so they are unable to function properly/efficiently. If the live rock is smoothered in detritus, the periphyton that would normally assist in keeping a system clean also perish. In such situations, steadily increasing NO3 and PO4 are what we commonly see since that's what we can easily measure.

Ralph.

 

[Cory]

All i can say is detrtus in our tanks is very different than detrtus in the sea.

Most "marine snow" iirc has been processed many times by living things already. Fish poo hasn't and neither has uneaten food, which id assume is the major component of aquarium detrtus. And if thats true, its a sink of po4/no3 accumulation.

 

[norskfisk]

A possible explanation to the OP observation that he harvested more biomass than he put into the aquarium could maybe be that the biomass he took out had a higher carbohydrate content than the one he put in. If his protein rich food acted as a high nitrogen fertilizer for carbohydrate rich algae or bacteria. So in effect one amino acid molecule in the input would become one amino acid molecule plus N carbohydrate molecules in the output. In that case the detritus he took out would not be food remains, but remains of algae and bacteria that were fertilized by the food remains.

 

[Paul B]

It is a packed sand-like materia (the dead diatom skeletons) that filters particulates as the water passes through it.

It actually looks more like powder and each "grain" of powder is full of holes about a micron in size. This is a micron------------> <-------------. I know, you can't see it. Neither can I, That is a micron.

 

[atoll]

All i can say is detrtus in our tanks is very different than detrtus in the sea.

Most "marine snow" iirc has been processed many times by living things already. Fish poo hasn't and neither has uneaten food, which id assume is the major component of aquarium detrtus. And if thats true, its a sink of po4/no3 accumulation.

What makes you believe detritus in our tanks isn't processed many times with fish eating other fishes poo, cuc in the sand, on and in the rocks and corals processing it, protein skimmers; mechanical filtration, chemical filtration, ATS's etc etc ? What I would like to see is some real research into detritus and I struggle to understand why there has not been. I could come up with a few conspiracy theories, however.