anyone run skimmerless tanks?

[dz6t]

My take on refugium is the benefit of producing live food for coral and fish. I am not very sure about its ability of removing nutrient and at least the rate of nutrient removal can be very slow. I think the important question is how much do you skim, over skimming or under skimming.

 

[KSC]

I've been running my 90gal sps tank skimmerless for a couple years. If you do a little research you might come to the conclusion that skimmers are highly inefficient and probably not needed in most tanks. Here's a good read on some skimmerless sps tanks- http://reefcentral.com/forums/showthread.php?t=2113546
Read the links in that thread, there's some good info there.

 

[HuuTa]

those tanks look amazing.thanks for the links Ksc.i might try it.i have been running my skimmer for 12 hrs a day.off at night.i don't dose anything.water change once a month.

 

[dcforester1]

Didn't a guest speak at one of our meetings about running a tank without a skimmer????

 

[inverted]

I've been running my 90gal sps tank skimmerless for a couple years. If you do a little research you might come to the conclusion that skimmers are highly inefficient and probably not needed in most tanks. Here's a good read on some skimmerless sps tanks- http://reefcentral.com/forums/showthread.php?t=2113546
Read the links in that thread, there's some good info there.

I agree that skimmers aren't "necessary". They are good insurance though. If a big anemone dies in your tank and you aren't around to do a water change, a skimmer may save your butt. Growing algae or bacteria, or whatever natural means of filtration your relying on, isn't going to respond nearly as fast.

I'd also have to disagree with your statement "skimmers are highly inefficient". Skimmers are highly efficient, nearly 100% so, at removing highly polar "amphiphilic" molecules. The problem is not all molecules are amphiphillic, some are purely hydrophobic and others purely hydrophillic. Most organic molecules, which are those which a skimmer is designed to remove are somewhere in between. The more in the middle ("amphiphilic"), the more likely a skimmer will remove it.

Much of the research on skimmers for us hobbyists these days comes from Ken Feldman. He like to say things such as "bubbles are really not a very effective medium for organic nutrient removal". However, what you need to keep in mind is that in saying such things, he is comparing skimmers to other methods, such as Granular Activated Carbon (GAC) or water changes etc... If you read more than the buzz line, he also often discusses the fact that to remove the same amount of organics with GAC for example, would be much more expensive than to do so with a skimmer, as the GAC while more effective, can become depleted quickly and needs to be replaced fairly often without a skimmer to take some of the load off. Likewise, water changes would need to be done more often without a skimmer. On a large system, the cost in time and money is more than would be with a skimmer. Using a skimmer is cheap and dosn't require much effort.

Now, many toxins and pollutants will bind to organics and become locked up. Many metals, such as copper do this very readily in a reef system and even at slightly elevated levels may be a non issue. So, short term, doing nothing may seem "fine" and you may not see much of a difference at all. The problems is, in a closed system, where there is constant input, they will accumulate if you don't remove them and eventually cause issues. You certainly don't need to remove them with a skimmer, but you need to remove them. A skimmer is just a very effective way to remove a large proportion of them, with regards to cost and labor. It also, as mentioned provides cheap insurance when things go wrong and your not around to take care of it.

 

[inverted]

I found a skimmer can significanly increase bio-load of a small or large tank because of increased air exchange.

I left this out of skimmer benefits because as you said a skimmer increases O2 and allows you to increase bioload. The problem I have with that is, when something happens, such as a power loss, or temperature spike, you've now significantly reduced the time your livestock can survive with the now reduced O2 levels. So, I think, especially with all the power failures as of late, there is a reasonable argument as to whether or not that's a good thing.

 

[me2003]

"An ATS can't remove organic carbon and actually adds some."
I agree that protein skimming has advantages if you remove algae from
an ATS system you are by definition removing organic carbon

 

[inverted]

"An ATS can't remove organic carbon and actually adds some."
I agree that protein skimming has advantages if you remove algae from
an ATS system you are by definition removing organic carbon

Algae is photoautotrophic, in other words, it produces organic carbon from CO2 and light. It dosn't use any of the organic carbon you are trying to remove via a skimmer i.e. the Dissolved Organic Carbon (DOC) in your tank. In fact, it releases byproducts which contain organic carbon, into the tank, created by CO2 and light, which wouldn't exist if the algae wasn't there in the first place. So, technically you remove Total Organic Carbon (TOC), but not DOC and the proportion of TOC removed was added by what your removing. If you add a fish to the tank and then remove it, you are removing TOC, but the TOC is the fish. If the fish poops ("byproduct"), from a meal eaten before you put it in the tank and you don't remove the poop, then like the algae, there was still a net increase in TOC due to the fish

 

[aiaman]

why would you not run a skimmer, lack of sump maybe?

 

[me2003]

"Algae is photoautotrophic"
Not all Algae is photoautotrophic
"it produces organic carbon from CO2"
CO2 can be produce by bacteria or yeast that break down organic carbon in the aquarium.

Since microalgae have this ability, their carbon metabolism can be divided into four types (1) photoautotrophy, (2) heterotrophy, (3) photoheterotrophy and (4) mixotrophy.

source of carbon for cyanobacteria growth can be organic substances, such as sugars, fatty acids and amino acids. However, the ability to grow heterotrophically or mixotrophically on one or other of the organic substrates is species dependent

 

[inverted]

Not all Algae is photoautotrophic

The purpose of an algae turf scrubber is to grow and harvest photoautotrophic "turf" algae, such as derbesia.

CO2 can be produce by bacteria or yeast that break down organic carbon in the aquarium.

Since microalgae have this ability, their carbon metabolism can be divided into four types (1) photoautotrophy, (2) heterotrophy, (3) photoheterotrophy and (4) mixotrophy.

source of carbon for cyanobacteria growth can be organic substances, such as sugars, fatty acids and amino acids. However, the ability to grow heterotrophically or mixotrophically on one or other of the organic substrates is species dependent

You definitely make an interesting point. There is a carbon cycle in the system. Regarding heterotrophy vs autotrophy though, I'd argue though that really, other than some species of dinofallegellates, I don't believe that any "algae", common to our systems are in any way heterotrophic. And certainly the purpose of an ATS is not to harvest heterotropic organism, but rather autotrophic "algae". Also, as you mentioned, Cyanobacteria can be mixotrophic, but is considered to be bacteria. Both cyano and dinos are generally considered nuisance organisms, if growing on an ATS anyways (perhaps we should harvest cyano, but that's another discussion), but regardless, are not generally (I say generally as I know of at least one species of cyano which, IIRC, was shown to grow as well in dark "heterotrophic mode" and light "autotrophic mode"- this appears to be an exception not the rule though) as efficient when living in heterotrophic modes. Some species can use heterotrophy for survival, but it isn't usually their primary "mode." So, here, I'll refer to algae as autotrophic and bacteria as heterotrophic (as, it is essentially is, at least for all reasonable intents and purposes as far as properly functioning ATSs are concerned).

As far as removal of organic carbon, as mentioned, bacteria can use DOC, and produce CO2. On the other hand, algae can consume CO2 and provide some DOC to the system (such as if there is excess after energy requirements are met). So, bacteria can benefit from the algae. Basically, the bacteria will be limited by the carrying capacity of the system and if this capacity is due to a carbon limitation, then the algae could provide more DOC for the bacteria, thereby, increasing the carrying capacity for bacteria. However, nutrients (N, P, Fe etc..) used by the bacteria will not be exported from the system unless the bacteria is removed from the system (and likewise if algae is the sink, will not be removed unless the algae is removed). At the same time however, CO2 is a noble gas and follows the ideal gas law. So, the CO2 level is dictated by the partial pressure of CO2 (pCO2). Therefore, assuming there is reasonable gas exchange, there is really no reliance of the algae on the bacteria, for CO2. For practical purposes, the algae is being removed, so, consumption is limited, and in comparison, the CO2 sink, when talking about a small system, is therefore essentially unlimited. So, the alga isn’t dependent on the bacteria.

However, the carrying capacity of algae and bacteria is, in both cases, also limited by the nutrients in the system (iron, nitrate, phosphate). The autotrophic algae however, as mentioned, aren’t reliant on the bacteria for energy, but are still competing with the bacteria for these non-carbon nutrients. The bacteria are reliant on organic carbon though, which needs to either come from food input, or the algae. If nutrients go to the bacteria, and your not exporting the bacteria, and these nutrients are not exported. If the ATS is set up correctly, your ideally creating an environment that shifts the competitive advantage for these last nutrients to the autotrophic algae. You harvest the algae, so, there is no space limitation and the algae can continue to grow and consume these nutrients. The carrying capacity for the algae is not met. So, if the size of the ATS is matched properly to the bioload of the system, nutrients decrease as the algae grows and is removed. However, still the net organic carbon does not decrease. Carbon used for metabolism is cycled, but carbon for growth remains in the algae or bacteria until that organism is removed. The nutrients coming into the system also bring carbon roughly in a standard proportion (such as the Redfield ratio). So, carbon for growth is basically fixed, but CO2 allows for an extra input. So, if the competitive advantage for resources is algae dominate, the carbon at best neutral. In order for organic carbon to decrease, there needs to be some form of mechanical filtration.

 

[inverted]

I guess lack of sump, lack of finances, desire to create a "natural" system, save electricity, belief that a skimmer removes "too much" etc.. We all have our opinions, there are certainly some valid arguments either way.

 

[me2003]

To be clear I think it is possible to run a skimmerless tank but it is a lot of extra work.
Most ATS/refugium are of poor design and not effective. The other option is a lot of water
changes. If you have a large tank salt can get very expensive. I have seen some interesting but somewhat
complex automatic water changing systems.
"desire to create a "natural" system," is an interesting technical challenge and I believe worth further research.
So I would agree with this earlier statement.

"I have run skimmerless (1.5yrs) and the trade off is not worth the wasted time/effort and reef budget to keep the tank in order. So it is possible but for me it is just not worth it And I would never even think about it on a SPS tank. "

 

[inverted]

BTW, I think the confusion is that when I mentioned "removing" OC, I was thinking in "net" terms and referring to "net" removal. If your thinking in gross terms, then a better wording would have been "reduction". Also, for some reason I see I typed CO2 is a "noble" gas. I have no idea what my fingers were thinking there.... it does act like a noble gas, in that it follows the ideal gas law, within the environmental parameters found in our tanks though. I think my fingers have a mind of their own sometimes.... good discussion!

 

[Sean Irwin]

I suspect that increasing organic carbon affects a coral's holobionet (the assemblage of all the microorganisms that live on or in a coral). This could be due to a change in species composition and/or alterations to resident microorganism gene expression or growth that leads to pathogenesis.

 

[dz6t]

Most ATS/refugium are of poor design and not effective. . "

You nailed it. I saw one working ATS was as big as a 125 gallon 6-foot tank.
Also, there is no way to create a system that close to "nature" unless it is very very large. All home reef tanks should be considered closed systems and should be treated as they are.

 

[Sean Irwin]

Marine biologists have done lots of experiments and no one has ever shown a strong association between nitrate/phosphate and coral mortality.

Sort of. Under controlled conditions, where only coral specimens are housed in aquaria, that statement would be true (though excess phosphate can reduce calcification rates). In nature, eutrophic conditions (high nitrogen and phosphate) favor algae that can readily outcompete corals.

Originally Posted by me2003
Most ATS/refugium are of poor design and not effective. . "
You nailed it. I saw one working ATS was as big as a 125 gallon 6-foot tank.
Also, there is no way to create a system that close to "nature" unless it is very very large. All home reef tanks should be considered closed systems and should be treated as they are.

Exactly, nutrient fixing depends on a system’s productivity. Bacteria reproduce much more rapidly than algae, doubling in minutes not hours.

 

[STiTCH87]

The only time i'd purposely NOT run a skimmer for longer than a temporary situation is in cases like my own as to where I have a 5g pico and running an efficient skimmer on it is down right impossible. A small in-tank filter and weekly water changes of 2 gallons will do the trick just fine though in my case and also is very inexpensive since its such a small tank. $1 per gallon of saltwater from my LFS equals $2 a week in water. With water, supplies, and electricity i'd say the tank only costs maybe $3-$4 a week to run.

 

[inverted]

I suspect that increasing organic carbon affects a coral's holobionet (the assemblage of all the microorganisms that live on or in a coral). This could be due to a change in species composition and/or alterations to resident microorganism gene expression or growth that leads to pathogenesis.

Yes I agree

Sort of. Under controlled conditions, where only coral specimens are housed in aquaria, that statement would be true (though excess phosphate can reduce calcification rates). In nature, eutrophic conditions (high nitrogen and phosphate) favor algae that can readily outcompete corals.

Definitely. I didn’t say "no association" though, just not a "strong" association. My 3rd and 4th references in post 16 discuss coral-algae interactions. Eutrophic conditions result from combinations of conditions; it's not just nitrate or phosphate that leads to coral mortality. You need a number of things to happen. You can have lots of nitrate, or phosphate, but if you don't have both, algae can't grow. Also, you will likely need various trace elements, lack of predators or various other combinations of factors.

As far as growth goes, nitrate and phosphate may decrease skeletal growth, but they can increase biomass/tissue growth. Also, they don't necessarily decrease skeletal growth under all conditions. They may, under some conditions. For example, one hypothesis for why nitrate decreases skeletal growth is related to inorganic carbon. The nitrate drives zooxanthellae, which outcompetes the coral for inorganic carbon reserves (hypothesized in Marubini and Davies (1996) "Nitrate increases zooxanthellae population density and reduces skeletogenesis in corals"). Phosphate is commonly believed to bind with calcium carbonate in the skeleton and inhibit skeletal formation. Another recent study though found phosphate resulted in less-dense skeletons, but linear growth was higher (see Dunn et al (2011) "Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach". If this turn out to be generalizable to hobby conditions, perhaps, in low energy environments, such as our tanks, this wouldn't be such an issue. There are definitely some questions though.

Exactly, nutrient fixing depends on a system’s productivity. Bacteria reproduce much more rapidly than algae, doubling in minutes not hours.

Bacteria may get first dibs on nutrients too, as it can utilize organics directly, whereas, for the most part, algae can't and must wait for it to be broken down into inorganic components first. And also, may form biofilms and share resources with other organisms, such as perhaps diazotrophs if N is low.

 

[STiTCH87]

I feel like people make reefing a thousand times more difficult than it really needs to be anyways. With the exception of SPS, a reef tank can easily be run sucessfully without a skimmer, test kits, or frequent water changes. I had a 29g that was usually skimmerless and only did a water change once or twice a month and it was always clean and sucessful and everything including softies and LPS grew extremely fast. I'm talking like one inch per month on a finger leather, double polyp amount every 2-3 months on zoas, and my frogspawn grew one or two new large heads per month. And I never dosed anything or tested anything I just left things alone and only did a deep clean when it looked dirty. Only had ich once from a clown that came in, and the hair algae only started towards the end because I was overfeeding with flake and frozen. Switched to pellets and fed less and voila no more algae. IMHO unless you have SPS, there's no need to get all fancy and scientific with keeping a tank.