Refugiums don't export nutrients?

[Veng]

 

GFO addresses phosphate (inorganic at that) in the water column... not in other places. Yes, you have to remove the GFO for it to actually export but because the energy requirement to break the GFO/Pi bond is so great and bacteria is lazy, it is removed for all intensive purposes. It is just not totally remove until you replace the media.

It still deserves it's own place just like algae, or mangroves, even if it only interacts with the inorganic phosphate. As drawn it is wrong.

 

Never said that fugess don't work or are bad. I just say they can not actually get to a low nutrient environment... they kinda give a false reading. The nutrients are still there and since not ALL of the algae is removed, it can be low nutrient by definition.

Uhh sure it can. Stop feeding the tank, and it will grow unto a point where it has moved to a low nutrient by definition as it can't pull anything more out to eat. The only question is if that relative level of phosphates is high enough for us to care. Empirical evidence abounds that it is low enough to be considered a low nutrient environment.

[FutureDoc]

 

Meaning: You have no frigging idea.

 

Let's call this a "lower nutrient system" we all get this. It's basic husbandry. Even if you do all these things, adding macroalgae can help get an "even lower nutrient system" by removing even MORE of the phosphates from the water.

Meaning that unless you specify a lot more than what you initially asked, it depends on a lot of variable and that would have too be addressed first.

 

Again, it is not about the "water" it is about the system. It is like counting cars on the highway to determine the number of cars owned in an area... you are missing all the parked cars that can at any moment become active.

[markalot]

 

Never said that fugess don't work or are bad. I just say they can not actually get to a low nutrient environment... they kinda give a false reading. The nutrients are still there and since not ALL of the algae is removed, it can't be low nutrient by definition.

 

See, thread falls on it's face. But it started the same way on TRT because of some folks hardline stance against refugiums period.

 

I changed can to can't above, which I think was the intent.

[FutureDoc]

It still deserves it's own place just like algae, or mangroves, even if it only interacts with the inorganic phosphate. As drawn it is wrong.

 

Uhh sure it can. Stop feeding the tank, and it will grow unto a point where it has moved to a low nutrient by definition as it can't pull anything more out to eat. The only question is if that relative level of phosphates is high enough for us to care. Empirical evidence abounds that it is low enough to be considered a low nutrient environment.

It is not drawn wrong... GFO address dissolved inorganic phosphate in the water column.

 

If you stop feeding a tank before the P concentration reaches above 0.009, then yes, it would remain a low nutrient system. But we no not stop feeding the tank for the most part.... at least most of us do not. I do have a fish-less softie system that is fed about once a month but that is about it.

[Amphiprion1]

Algae can not "store" or "pool" resources... not sure if you intended this comment exactly how I read it but lets move on. It can be a tightly cycled process and therefore preventing the algae from getting it is an important factor. Algae's coping mechanism is to control its biomass and match that of the surrounding environment so in lean times, it decreases mass to survive and then in boom times it increases.. the algae-fuge is the example of that boom and is why although water test might say one thing, that in reality, algae is saying another.

 

TRT actually has a great algae "can and can't do thread" if you are interested. Good references too... but it is still building.

http://www.thereeftank.com/forums/f77/algae-whats-under-the-hood-how-does-it-do-and-what-cant-it-do-198321.html

No, they actually do and many are able to maintain a surplus in the form of polyphosphates. In times of P starvation, many algae are capable of increasing intracellular P significantly. Many bacteria are able to do the same.

 

I think we are all trying to oversimplify and out-explain a far more complex process to prove a point. I'm not even going to pretend that I understand these dynamics to a real extent.

[jedimasterben]

So after all that back and forth, let me get this straight - if I have a system that has 1.0ppm of phosphate, and I put algae in it, and the phosphate then reads 0.0ppm and the algae is removed, the phosphate reading is still 1.0ppm?

[FutureDoc]

See, thread falls on it's face. But it started the same way on TRT because of some folks hardline stance against refugiums period.

 

I changed can to can't above, which I think was the intent.

 

Refugiums just are not necessary for most tanks. They are like wet/dry filters. They provide a very specific service to a very specific ecotype. However, unlike wet/dry, folks are advocating algae for something it can not do. That is the simple just of it. They can not limit P, rather they cover it up.

[dtitus1]

I am. kgoldy is.

 

photobucket.com

imageshack.us

imgur.com

 

just to name a few.

 

You must have a s4itload of macros then, even then I would still worry about non-soluable waste building up long term. Not everything produced by metabolic processes going on is exported through macro and while it would take a long time eventually these would build up and could cause problems without at least SOME maintenance.

[FutureDoc]

So after all that back and forth, let me get this straight - if I have a system that has 1.0ppm of phosphate, and I put algae in it, and the phosphate then reads 0.0ppm and the algae is removed, the phosphate reading is still 1.0ppm?

 

What? If the P is 1ppm, do a water change, siphon the detritus.

 

Who uses algae and removes ALL of it?

[jedimasterben]

You must have a s4itload of macros then, even then I would still worry about non-soluable waste building up long term. Not everything produced by metabolic processes going on is exported through macro and while it would take a long time eventually these would build up and could cause problems without at least SOME maintenance.

Aye, I do. My macros are sold/dumped and restocked with new algaes from the Atlantic every few months. I run a large algae scrubber that can remove so much nitrate from the water as to starve clams and make SPS fade. I also have run Purigen and ROX carbon in a reactor, but it clogged up and has not been running for a while now, and things actually look better as far as corals go.

 

What? If the P is 1ppm, do a water change, siphon the detritus.

 

Who uses algae and removes ALL of it?

I think you missed what I was saying. What does detritus have to do with a current phosphate reading, not a future phosphate reading?

[Griever]

So after all that back and forth, let me get this straight - if I have a system that has 1.0ppm of phosphate, and I put algae in it, and the phosphate then reads 0.0ppm and the algae is removed, the phosphate reading is still 1.0ppm?

 

That's what it sounds like, Doc is measuring some quantum tunneling Phosphate that can't be measured by our test kits. /s (I do understand the point he's making, I just don't think it's exactly applicable to the discussion we're trying to have. We know algae doesn't magically remove all phosphate).

 

If you have a routine, and you add a refugium without changing the routine, I'm not sure where all this extra phosphate is coming from, in his argument. There's conservation of mass, and if you remove even some phosphate when you harvest your macro algae, it's a net reduction. You'd have to do a lot of figuring though if you want to argue that this method could export ALL phosphate you add to the aquarium, but I don't see any argument that makes a case for a refugium being patently bad for your tank.

[markalot]

 

Uhh sure it can. Stop feeding the tank, and it will grow unto a point where it has moved to a low nutrient by definition as it can't pull anything more out to eat. The only question is if that relative level of phosphates is high enough for us to care. Empirical evidence abounds that it is low enough to be considered a low nutrient environment.

 

But for how long? The theory, as I read it, is you can appear to have a low nutrient system, to the extent I care about anyway, for a while but because the phosphates are binding to sand / rocks eventually the binding will stop and you will have a phosphate problem where none existed before. The binding happens before algae or GFO can get to it.

 

So tanks looks terrific from 6 months or so until about 2 years old, depending on what's in the tank, and then problems start.

 

Here is a 6 year old profile winner from years ago: http://www.nano-reef.com/featured/_/2008/tashayar-r12

 

Low tech, obviously not low nutrient. Why at year 2 did she have algae issues and why did they go away? She pulled the algae and did water changes, and then it was over and the tank continued for at least 3 more years. What happened, why did it stop?

 

Another theory is that aggressive GFO can reverse this binding. I've seen this countered by stating that hair algae will use the phosphate as it is unbound before it gets to the refugium or GFO. This is why so many with older tanks read 0 phosphates but are suffering a massive hair algae outbreak. Again, no idea how accurate that is.

[FutureDoc]

I will leave y'all with this for the day. To clarify:

 

Growing algae in a system as a means of "export" by trophic definition can not be a low nutrient system. Thus algae as a means of achieving a low nutrient system (one that mimics the stony reef-crest and back reef) is impossible.

 

The test kits sold to hobbyist are inaccurate. They can not read to P limiting levels. They can only test for inorganic P in the water column, not organic P. The window of error is quite large +/- 0.4ppm. So pointing to the test kit as "proof" while algae is growing with ample biomass is a very big mistake.

 

Algae does not permanently bind P and hold on to it until you decide to remove it... it is involved in active exchange within a P cycle that is also dependent on bacteria and Ca within our tanks.

 

Take a "systems" approach and use bio-indicators. Works well in ecology

[markalot]

So after all that back and forth, let me get this straight - if I have a system that has 1.0ppm of phosphate, and I put algae in it, and the phosphate then reads 0.0ppm and the algae is removed, the phosphate reading is still 1.0ppm?

 

Now why do you say it this way?

 

When bacteria converts the phosphates and they move into the water column do you think your algae scrubber and macros get the first crack at them? Could anything else get to them first? Could that be a future problem?

 

All we know is that in the end you read 0 phosphates, meaning you have a low enough nutrient system for everything to be damn happy and look great. I don't know the answers but I think it's fair game to consider the questions. If something else is binding the phosphates first and that binding ever stops then it's a whole new ballgame. For all I know it simply means your macros grow faster and your scrubber needs harvested more often but all remains great. I think that's a reasonable conclusion, but I just don't know.

[Veng]

It is not drawn wrong... GFO address dissolved inorganic phosphate in the water column.

It is a part of the cycle no different than the algae and should be drawn as such.

If you stop feeding a tank before the P concentration reaches above 0.009, then yes, it would remain a low nutrient system. But we no not stop feeding the tank for the most part.... at least most of us do not. I do have a fish-less softie system that is fed about once a month but that is about it.

If you have enough macro, then it will keep the phosphates below 0.01. It's like saying if you have a parking lot with cows in it, you can't have a low hay system if you have cows to feed. Sure you can. Just have enough cows that the hay is eaten the second it hits the ground. As soon as the phosphate is freed from anything (rotting food, detris, rocks unbinding, whatever).

 

 

Refugiums just are not necessary for most tanks. They are like wet/dry filters. They provide a very specific service to a very specific ecotype. However, unlike wet/dry, folks are advocating algae for something it can not do. That is the simple just of it. They can not limit P, rather they cover it up.

No one said refugiums are necessary. No one here thinks they are required, everyone knows there are alternatives. It's one method to achieve low P. They can, and do limit P if they are sized right for the system.

 

What? If the P is 1ppm, do a water change, siphon the detritus.

 

Who uses algae and removes ALL of it?

Who removes all the detritus in a siphon? Who removes all their water in a water change? I guess we better stop doing water changes and stop siphoning detritus cause we don't remove 100% of it. Wait, what?

 

 

I will leave y'all with this for the day. To clarify:

 

Growing algae in a system as a means of "export" by trophic definition can not be a low nutrient system. Thus algae as a means of achieving a low nutrient system (one that mimics the stony reef-crest and back reef) is impossible.

False, it can not be a zero nutrient system, it can however be a low nutrient system.

The test kits sold to hobbyist are inaccurate. They can not read to P limiting levels. They can only test for inorganic P in the water column, not organic P. The window of error is quite large +/- 0.4ppm. So pointing to the test kit as "proof" while algae is growing with ample biomass is a very big mistake.

False, kits are commonly available that test to 0.02ppm accuracy. http://www.redseafish.com/index.aspx?id=4369

Algae does not permanently bind P and hold on to it until you decide to remove it... it is involved in active exchange within a P cycle that is also dependent on bacteria and Ca within our tanks.

False. It does not bind ALL P that it uses, but it does bind some.

[jedimasterben]

Now why do you say it this way?

 

When bacteria converts the phosphates and they move into the water column do you think your algae scrubber and macros get the first crack at them? Could anything else get to them first? Could that be a future problem?

 

All we know is that in the end you read 0 phosphates, meaning you have a low enough nutrient system for everything to be damn happy and look great. I don't know the answers but I think it's fair game to consider the questions. If something else is binding the phosphates first and that binding ever stops then it's a whole new ballgame. For all I know it simply means your macros grow faster and your scrubber needs harvested more often but all remains great. I think that's a reasonable conclusion, but I just don't know.

To prove a point - point being that macroalgaes do, indeed, use phosphate and remove it from the water column, which seems to be the point that Mr. Doc is trying to disprove. I have the ability to test this with my tank - I turn off the lighting to the algae scrubber and refugium, and phosphate levels will rise, and when those lights come back on, phosphate will fall. That, I know, is factual.

[markalot]

To prove a point - point being that macroalgaes do, indeed, use phosphate and remove it from the water column, which seems to be the point that Mr. Doc is trying to disprove. I have the ability to test this with my tank - I turn off the lighting to the algae scrubber and refugium, and phosphate levels will rise, and when those lights come back on, phosphate will fall. That, I know, is factual.

 

Well, I read him saying it's much more efficient to remove it prior to it entering the water column and that if it gets to the water column a lot of things will "use" it, including the algae. His last statement about not running a true low nutrient system is NOT helpful.

 

If your tank continues for a few years you may be able to prove or disprove this. I expect your phosphate load (the phosphate that needs to be removed) to increase as the tank ages, assuming inputs stay the same. This will be due to the rock and sand not binding some of it as efficiently, or eventually not binding it at all. You can measure your rate of change today, and again every month to see if this is true or not.

 

if today, phosphate rises by 1ppm an hour and 6 months from now 3 ppm per hour, what changed? That's a big if, of course.

 

If your filter can handle it, though, then why care?

 

Just don't vanish, like so many do when they have problems.

[Veng]

 

Well, I read him saying it's much more efficient to remove it prior to it entering the water column and that if it gets to the water column a lot of things will "use" it, including the algae. His last statement about not running a true low nutrient system is NOT helpful.

 

If your tank continues for a few years you may be able to prove or disprove this. I expect your phosphate load (the phosphate that needs to be removed) to increase as the tank ages, assuming inputs stay the same. This will be due to the rock and sand not binding some of it as efficiently, or eventually not binding it at all. You can measure your rate of change today, and again every month to see if this is true or not.

 

if today, phosphate rises by 1ppm an hour and 6 months from now 3 ppm per hour, what changed? That's a big if, of course.

 

If your filter can handle it, though, then why care?

 

Just don't vanish, like so many do when they have problems.

I find it hard to believe it takes years to fill up the binding capacity of a rock when we can fill up the binding capacity of GFO in a few days. If rock can really bind that much phosphates, shouldn't we be using rock instead of GFO?

 

There are lots of ways to do things in this hobby, and not all of them scale well economically or size wise when you go from a 1,000 gallons to 1 gallon as your range of tanks.

[Griever]

I find it hard to believe it takes years to fill up the binding capacity of a rock when we can fill up the binding capacity of GFO in a few days. If rock can really bind that much phosphates, shouldn't we be using rock instead of GFO?

 

There are lots of ways to do things in this hobby, and not all of them scale well economically or size wise when you go from a 1,000 gallons to 1 gallon as your range of tanks.

 

My first thought was to sell dry rock rubble as magic phosphate binder for people to put into their sumps and throw away every month. I'll make a fortune!

[doppelganger]

too much to read but I'll just post my experience.

 

I have a 20 Long, mixed reef. Been up for about 1.5 years. 3 fish in there, I feed every other day for the most part and feed my coral heavily with frenzy and mysis. I don't run a skimmer anymore. I use to, in fact it's still in there. I haven't done a water change in almost a month. My nitrates are still very low (I'm actually trying to raise them cuz I have more lps than sps). SPS are still growing fine tho. Even then it's hard to get my nitrates up.

 

The only export of nutrients is a red macro that I have in the back. I can't remember the name. It grows quite fast and I blast it with like 600 lumens of white light point blank. I have a shallow sand bed as well. I can't provide data sheets or wutever but just my experience based on my tank. There's really nothing else in my tank other than macro that can keep my nitrates and phosphates in check.

[Reefin Dude]

Geoff here just so nobody is confused.

 

i think the problem people are having is how organisms use phosphates, and how we tend to try and clump all phosphates together, which is very problematic. algae is not capable of accessing phosphates when they are organically bound, while animals are. the opposite is also true. the animals we keep are not capable of accessing water soluble phosphates. our phosphate test kits are also only able to test for water soluble phosphates missing over half of the entire picture. while it is true that feeding less will end up in less Pi later on, it also means less energy for the animals we spent good money on. if there is a lot of Pi in the system (the fact that algae is growing is an example of having a nutrient problem) then there must be a lot of bacteria at work on waste to create it. the Pi has to come from somewhere, it just does not show up out of no where. i think this is the point that most people miss. you can put as much food into a tank as you want as long as you can remove it before it rots. the only way wastes are going to become Pi is if it is kept as a pet also and allowed to rot. Pi is a waste product. going to the chart Futuredoc posted you can see where the various areas for breaking the phosphate chain and how it affects those organisms that use them. if all we want to do is feed the critters we bought, then why have the waste Pi around at all?

 

not all corals require the same environment. softies and SPS require completely different phosphate types in order to thrive. SPS require organic phosphates from feeding in order to feed the zoax within them. softies do not, the zoax inside of them feed off of the freely available Pi in the water column. Pi does in fact clog up the calcium pump in SPS corals if the levels get high enough. there is a reason why they deposit a skeleton, it is a by product of photosynthesis without easily available elemental carbon and phosphates.

 

how does one design the perfect "refugium"? is it with a very high flow through it? some food for thought. what if "refugiums" and ATS are not outcompeting the display for Pi, but are outcompeting the display for detritus. does the observations still add up. the fact that nitrates and phosphates go down and algae does not seem to grow as well in the display? where was the algae growing in the display before an ATS/"refugium" was put on line? was it in the lower flow areas where detritus would normally accumulate first?

 

everyone is so concerned about phosphates, rightfully so, but the understanding on how it is used has been poorly represented by the "sand experts" of the past 15 years.

 

G~

[William]

I will leave y'all with this for the day. To clarify:

 

Growing algae in a system as a means of "export" by trophic definition can not be a low nutrient system. Thus algae as a means of achieving a low nutrient system (one that mimics the stony reef-crest and back reef) is impossible.

 

The test kits sold to hobbyist are inaccurate. They can not read to P limiting levels. They can only test for inorganic P in the water column, not organic P. The window of error is quite large +/- 0.4ppm. So pointing to the test kit as "proof" while algae is growing with ample biomass is a very big mistake.

 

Algae does not permanently bind P and hold on to it until you decide to remove it... it is involved in active exchange within a P cycle that is also dependent on bacteria and Ca within our tanks.

 

Take a "systems" approach and use bio-indicators. Works well in ecology

 

 

1) You are correct a 0 reading on a test kit means nothing, and most test kits are not sensitive enough to discriminately get down to the .009 level you mentioned. This fact should also be taken into account when you assess your P removal method. therefore, all testing done on any of the tanks we are talking about (save ones using "high-end" testing techniques) is essentially useless. If my reasoning is correct, then how do you know that your tanks are achieving .009

 

2) What specific data do you have that proves that it is necessary to maintain a system at or below "natural" reef P in order to promote calcified coral growth? especially since most of our home aquariums are vastly different in many other elements from a "natural" reef.

 

3) Is it your assumption that tanks that utilize refugiums, do not do so as a means to provide "natural" food for their tanks. So that they can reduce the amounts of exogenous nutrients added to tanks over time.

 

4) do you assume that tanks that utilize a refugium, do not also utilize a method of bacterial removal? (Ie a skimmer)

 

Just a couple of questions

[Reefin Dude]

My first thought was to sell dry rock rubble as magic phosphate binder for people to put into their sumps and throw away every month. I'll make a fortune!

and why do you not think this is actually what is going on in our systems. read up on phosphate binding and calcium carbonate. calcium carbonate is actually a very good phosphates binder. equal to GFO and aluminum oxide. this is where our problems begin and end. have you ever really thought about how a substrate works? it works by the slow migration of phosphate laden material down through it. the top layers bind phosphates directly. it is binding reaction. the bacteria cleave it off for use as energy in their biological processes just like most organisms. they die, or are pushed deeper into the substrate by other bacteria or by benthic organisms. leaving more free sites at the surface of the substrate for more phosphate binding. this is the same process as what is going on in the LR. the only difference is that LR is open all around and the flow of the water column is able to blow away the resulting phosphate laden detritus, in effect self cleaning the LR. this is what "cooking"/purging LR is. unfortunately for the substrate there is a bottom to the tank and the detritus starts filling up the substrate chocking out the migration of phosphates. once the chocking starts the bacteria also run out of elemental carbon to thrive bringing the whole process to a grinding halt. this is the greatest misconception out there in the SW hobby. that the calcium carbonate substrate we use is anything other than a huge phosphate sink. everyone focuses on algae for uptaking phosphates, but few talk about the calcium carbonate and its role.

 

there is nothing wrong with using a substrate as a phosphates sink and replacing it every so often. heck you can just fill those silly GFO reactors with the stuff and it will act the same. it will need to be replaced more often though because bacteria are able to cleave phosphates off of Calcium carbonate easier than GFO or aluminum oxide.

 

i was thinking we would get into this process later, but great segway Greiver.

 

G~

[William]

and why do you not think this is actually what is going on in our systems. read up on phosphate binding and calcium carbonate. calcium carbonate is actually a very good phosphates binder. equal to GFO and aluminum oxide. this is where our problems begin and end. have you ever really thought about how a substrate works? it works by the slow migration of phosphate laden material down through it. the top layers bind phosphates directly. it is binding reaction. the bacteria cleave it off for use as energy in their biological processes just like most organisms. they die, or are pushed deeper into the substrate by other bacteria or by benthic organisms. leaving more free sites at the surface of the substrate for more phosphate binding. this is the same process as what is going on in the LR. the only difference is that LR is open all around and the flow of the water column is able to blow away the resulting phosphate laden detritus, in effect self cleaning the LR. this is what "cooking"/purging LR is. unfortunately for the substrate there is a bottom to the tank and the detritus starts filling up the substrate chocking out the migration of phosphates. once the chocking starts the bacteria also run out of elemental carbon to thrive bringing the whole process to a grinding halt. this is the greatest misconception out there in the SW hobby. that the calcium carbonate substrate we use is anything other than a huge phosphate sink. everyone focuses on algae for uptaking phosphates, but few talk about the calcium carbonate and its role.

 

there is nothing wrong with using a substrate as a phosphates sink and replacing it every so often. heck you can just fill those silly GFO reactors with the stuff and it will act the same. it will need to be replaced more often though because bacteria are able to cleave phosphates off of Calcium carbonate easier than GFO or aluminum oxide.

 

i was thinking we would get into this process later, but great segway Greiver.

 

G~

 

Do you have any specific paper on this, I would like to know more. I have university access so i should be able to see most published papers.

 

.................

 

I also think we should clarify what we are calling a refugium (for me it is a 10gal part of my fuge with a huge ball of chetto and a powerhead on the bottom to still detritus). I also carbon dose in the following chamber, which is then removed via skimming.

 

Tank -> filter sock -> "refugium" -> organic carbon chamber -> Skimmer -> return.

and my inaccurately tested Pi has been very low.

 

If the goal is just having low Pi, then I would agree that algal based export is not the most efficient. However, if I am not mistaken, there are other aspects to coral husbandry (read sps), besides Pi, that on a practical scale (read normal aquarium environment) that would be sacrificed to achieve the level of Pi established by the Doc.

[Reefin Dude]

1) You are correct a 0 reading on a test kit means nothing, and most test kits are not sensitive enough to discriminately get down to the .009 level you mentioned. This fact should also be taken into account when you assess your P removal method. therefore, all testing done on any of the tanks we are talking about (save ones using "high-end" testing techniques) is essentially useless. If my reasoning is correct, then how do you know that your tanks are achieving .009

 

2) What specific data do you have that proves that it is necessary to maintain a system at or below "natural" reef P in order to promote calcified coral growth? especially since most of our home aquariums are vastly different in many other elements from a "natural" reef.

 

3) Is it your assumption that tanks that utilize refugiums, do not do so as a means to provide "natural" food for their tanks. So that they can reduce the amounts of exogenous nutrients added to tanks over time.

 

4) do you assume that tanks that utilize a refugium, do not also utilize a method of bacterial removal? (Ie a skimmer)

 

Just a couple of questions

argh, i can not figure out how to get the html editor on a post on this site to make this easier to follow.

 

1). use the biomarkers. algae, pods, whatever. they are all better indicators of the trophic level of a system than the test kits we currently have. we see the outer reefs without algae, and they are at 0.005ppm, we know that oligotrophic ends at 0.009ppm, therefore if there is algae, the phosphate levels must be above 0.009ppm to support the algae. we are just trying to hard. not using the tools available.

 

2) are you looking for papers on Pi levels for inhibiting growth in hermatypic organisms? or just the processes that are disrupted when Pi is freely available? something to remember is that not all corals come from the same trophic environment. some can handle higher Pi levels than others and still survive. which natural reef? the outer, lagoon, back? i would say we can get pretty close to the outer reef if the tank is designed properly. where the vast majority of phosphates is in the form of organically bound and coming in on the incoming tide as plankton.

 

3) what "natural" food? pods and other benthic inverts? these are again just another sign that there is enough free nutrients to support their population. think of all of the free nutrients needed to support the ecosystem up to that "natural" food. where is all of this coming from? are we more interested in feeding the critters we paid good money for or all of the free loaders in the system? what good are they doing besides creating more steps in the phosphate chain which is already showing that the system is become more eutrophic. how are they reducing the amount of nutrients? if they are eaten, the nutrients are still in the tank. we must export something in order to remove phosphates.

 

4) can't answer this one for FD, but i would hazard to guess that no is the answer. he assumes skimmers are used all of the time. skimmers do however only remove bacteria and other organisms that are in the water column, not the rest of the bacterial biomass located elsewhere.

 

G~