MCsaxmaster
New member
Ahhhhh, a cOlorimiter, not a cAlorimiter. Now it makes sense.
Anyone seen drastic improvement from phosphate removers?
- Thread starter foshizzle
- Start date
hehhehehe colorimeter. what is sorokins book?
hey mark that is the best advice I have heard in a long long time. read alot,think for yourself.
doesn't seem like alot of people around me do that much anymore.
mc I found the articles decent and they did state they weren't sure on some of the stuff they were describing. I am old in the hobby but fairly new into trying to understand what is really going on past the nitrogen cycle so I really wouldn't know what part were wrong or not proven. I am very interested in any other readily available material you might know of.
thanks,
robert
hey mark that is the best advice I have heard in a long long time. read alot,think for yourself.
doesn't seem like alot of people around me do that much anymore.
mc I found the articles decent and they did state they weren't sure on some of the stuff they were describing. I am old in the hobby but fairly new into trying to understand what is really going on past the nitrogen cycle so I really wouldn't know what part were wrong or not proven. I am very interested in any other readily available material you might know of.
thanks,
robert
You sure? I was thinking it was the other way around. Got a link?
I'm not using zeovit, but why do you think it works? Extremely low nutirents, lots of food.
Sure. Isn't that the goal of every method of reefkeeping?
It may be the goal, but not common practice. Most people are so worried about nutrient control they forget all about feeding. My thinking is that GFO would allow me to feed more while keeping orthophosphate levels closer to ACTUAL 0. (I don't see N buildup happening in my system).
Are you saying GFO is only useful where inorganic PO4 levels are detectable or high enough to spur algae growth? Otherwise the orthophosphate is being taken up too fast to affect calcification or zoox? Why then do I see so many experienced hobbiests using GFO when their tanks already test at 0?
MCsaxmaster
New member
mc I found the articles decent and they did state they weren't sure on some of the stuff they were describing. I am old in the hobby but fairly new into trying to understand what is really going on past the nitrogen cycle so I really wouldn't know what part were wrong or not proven. I am very interested in any other readily available material you might know of.
Hi Rob. To be honest, the only way I could explain exactly what is right and what is wrong is by going point by point through the articles. Suffice it to say, however, that most of the processes that they describe as factual and several assumptions they make are just flat-out wrong. I'm not sure where else might be a good source to tell the truth (besides wading through professional journals). I'm actually working on a series that will address these issues for Reefkeeping though. If they decide to pick it up, it's probably going to be 6 or 7 articles. Hopefully you'll have some answers and a better understanding of nutrient dynamics on reefs by Christmas
Besides, zooxanthellae are likely N-limited, not P-limited. Fertilizing them with P shouldn't get a growth response under normal circumstances.
You sure? I was thinking it was the other way around. Got a link?
In nature zooxanthellae are definitely N-limited before P-limited. It's possible to have it the other way around in a reef tank (high DIN and very low DIP), but that would be pretty abnormal circumstances. I speak to this a bit in the "sps" section of my RK article this month. I can provide further references if needed.
It may be the goal, but not common practice. Most people are so worried about nutrient control they forget all about feeding.
Couldn't agree more :thumbsup: Definitely a big problem in a lot of reef tanks.
My thinking is that GFO would allow me to feed more while keeping orthophosphate levels closer to ACTUAL 0. (I don't see N buildup happening in my system).
Ok. But if you aren't seeing phosphate levels rise, why do you need the GFO to lower them? Aren't you then using GFO, which can potentially cause problems according to some aquarists--I don't use it myself so don't have experience with that--to try to do something that is already being done by the organisms in the tank and the equipment you already have?
Are you saying GFO is only useful where inorganic PO4 levels are detectable or high enough to spur algae growth?
Well, I suppose what I'm saying is that I don't see any reason to use them if phosphate is undetectable and there's no problem algae. Obviously phosphate is not overly abundant in that case, why would one need to futher lower it?
Otherwise the orthophosphate is being taken up too fast to affect calcification or zoox?
Orthophosphate at undetectable levels on decent test kits (say, <0.03 ppm) isn't high enough to impact calcification. As above, P doesn't normally limit zooxanthellae. You could fill an aquarium with natural seawater, put in a coral, and dump in a bunch of phosphate and wouldn't see any response from the zooxanthellae. Of course the coral wouldn't be diggin the situation too much, but the zooxanthellae already have sufficient P. Adding more won't affect them. But like I said, if the N
ratios in a tank are really skewed abnormally (very high N) THEN it is possible that the zoox. might be P-limited.
Why then do I see so many experienced hobbiests using GFO when their tanks already test at 0?
Good question. I suppose you'd have to ask them as I couldn't answer that. I would suggest, however, that people are often much like sheep, especially reef aquarists
Best,
Chris
Hi Rob. To be honest, the only way I could explain exactly what is right and what is wrong is by going point by point through the articles. Suffice it to say, however, that most of the processes that they describe as factual and several assumptions they make are just flat-out wrong. I'm not sure where else might be a good source to tell the truth (besides wading through professional journals). I'm actually working on a series that will address these issues for Reefkeeping though. If they decide to pick it up, it's probably going to be 6 or 7 articles. Hopefully you'll have some answers and a better understanding of nutrient dynamics on reefs by Christmas
Besides, zooxanthellae are likely N-limited, not P-limited. Fertilizing them with P shouldn't get a growth response under normal circumstances.
You sure? I was thinking it was the other way around. Got a link?
In nature zooxanthellae are definitely N-limited before P-limited. It's possible to have it the other way around in a reef tank (high DIN and very low DIP), but that would be pretty abnormal circumstances. I speak to this a bit in the "sps" section of my RK article this month. I can provide further references if needed.
It may be the goal, but not common practice. Most people are so worried about nutrient control they forget all about feeding.
Couldn't agree more :thumbsup: Definitely a big problem in a lot of reef tanks.
My thinking is that GFO would allow me to feed more while keeping orthophosphate levels closer to ACTUAL 0. (I don't see N buildup happening in my system).
Ok. But if you aren't seeing phosphate levels rise, why do you need the GFO to lower them? Aren't you then using GFO, which can potentially cause problems according to some aquarists--I don't use it myself so don't have experience with that--to try to do something that is already being done by the organisms in the tank and the equipment you already have?
Are you saying GFO is only useful where inorganic PO4 levels are detectable or high enough to spur algae growth?
Well, I suppose what I'm saying is that I don't see any reason to use them if phosphate is undetectable and there's no problem algae. Obviously phosphate is not overly abundant in that case, why would one need to futher lower it?
Otherwise the orthophosphate is being taken up too fast to affect calcification or zoox?
Orthophosphate at undetectable levels on decent test kits (say, <0.03 ppm) isn't high enough to impact calcification. As above, P doesn't normally limit zooxanthellae. You could fill an aquarium with natural seawater, put in a coral, and dump in a bunch of phosphate and wouldn't see any response from the zooxanthellae. Of course the coral wouldn't be diggin the situation too much
, but the zooxanthellae already have sufficient P. Adding more won't affect them. But like I said, if the N ratios in a tank are really skewed abnormally (very high N) THEN it is possible that the zoox. might be P-limited.Why then do I see so many experienced hobbiests using GFO when their tanks already test at 0?
Good question. I suppose you'd have to ask them as I couldn't answer that. I would suggest, however, that people are often much like sheep, especially reef aquarists
Best,
Chris
That was a very good explanation of phosphate Chris.
I researched NSW nutrient levels and am striving to recreate the levels found around reefs. Ocean water around reefs has PO4 levels of about 0.005-0.03ppm, and most commonly about 0.01ppm. Above about 0.03ppm will start to interfere with calcification of corals. I have the Salifert phosphate test kit, which is supposedly able to detect 0.03ppm PO4. I defy anyone to reliably differentiate between the almost imperceptible blue of 0.03 vs. the white of "undetectable". I know I can't. The next step up is 0.1ppm. That is the first level I think can be accurately detected.
I now have a colorimeter and a standard solution of phosphate which I have used to calibrate the colorimeter. It can reliably detect levels of 0.03ppm and possibly 0.02ppm. Testing the Salifert kit is difficult since the reading is subjective. I know that a solution of 0.03ppm PO4 still looks white to me with that kit.
As far as aquaria being nitrate limited, that will vary by the aquarium. Supposing a tank has a PO4 level of 0.03ppm, then the tank would be nitrate limited if the NO3 level is below 0.30ppm (the Redfield ratio adjusted to ppm from atomic ratio) and PHOSPHATE LIMITED if the nitrate level is above 0.3ppm. Certainly many reef aquaria have nitrate levels higher than that. My nitrate regularly tests below 0.2ppm by colorimeter, which is still above NSW levels of 0.03 to 0.10ppm. Based on those numbers, my tank is in fact nitrate limited.
I use small amounts of GFO and I dose sugar (instead of vodka) daily because I feed alot. If I had no problem algae I would stop using the GFO, but despite those low nutrient measurements I continue to have a problem with some turf algae. It may not be helping, I don't know. Certainly if it is it is incremental. I believe that a PO4 level of 0.01 or 0.02 is better than 0.03. As long as my PO4 is always testing at least 0.02ppm I will continue using GFO's.
Allen
I researched NSW nutrient levels and am striving to recreate the levels found around reefs. Ocean water around reefs has PO4 levels of about 0.005-0.03ppm, and most commonly about 0.01ppm. Above about 0.03ppm will start to interfere with calcification of corals. I have the Salifert phosphate test kit, which is supposedly able to detect 0.03ppm PO4. I defy anyone to reliably differentiate between the almost imperceptible blue of 0.03 vs. the white of "undetectable". I know I can't. The next step up is 0.1ppm. That is the first level I think can be accurately detected.
I now have a colorimeter and a standard solution of phosphate which I have used to calibrate the colorimeter. It can reliably detect levels of 0.03ppm and possibly 0.02ppm. Testing the Salifert kit is difficult since the reading is subjective. I know that a solution of 0.03ppm PO4 still looks white to me with that kit.
As far as aquaria being nitrate limited, that will vary by the aquarium. Supposing a tank has a PO4 level of 0.03ppm, then the tank would be nitrate limited if the NO3 level is below 0.30ppm (the Redfield ratio adjusted to ppm from atomic ratio) and PHOSPHATE LIMITED if the nitrate level is above 0.3ppm. Certainly many reef aquaria have nitrate levels higher than that. My nitrate regularly tests below 0.2ppm by colorimeter, which is still above NSW levels of 0.03 to 0.10ppm. Based on those numbers, my tank is in fact nitrate limited.
I use small amounts of GFO and I dose sugar (instead of vodka) daily because I feed alot. If I had no problem algae I would stop using the GFO, but despite those low nutrient measurements I continue to have a problem with some turf algae. It may not be helping, I don't know. Certainly if it is it is incremental. I believe that a PO4 level of 0.01 or 0.02 is better than 0.03. As long as my PO4 is always testing at least 0.02ppm I will continue using GFO's.
Allen
wentreefgirl
New member
Heres a visual for ya.
No phosphate remover.
<img src="http://img.photobucket.com/albums/v298/wentreefgirl/Tank%20pics/Picture1895126567.jpg">
With.
<img src="http://img.photobucket.com/albums/v298/wentreefgirl/Tank%20pics/Picture517937750.jpg">
No phosphate remover.
<img src="http://img.photobucket.com/albums/v298/wentreefgirl/Tank%20pics/Picture1895126567.jpg">
With.
<img src="http://img.photobucket.com/albums/v298/wentreefgirl/Tank%20pics/Picture517937750.jpg">
MCsaxmaster
New member
Al,
Sure, I never said that it was impossible to have a P limited tank in terms of algal growth. In fact, I stated just the opposite...a couple times I think
On reefs in nature algae are always (well, >99% of the time I'll say, to allow for weird situations) N-limited on reefs. In the open ocean near continents phytoplankton tend to be barely N-limited or N and P co-limited. Far from continents they tend to Fe-limited (southern ocean).
So yes, if (for example) a person had a reef tank where the water had a DIP concentration of 0.03 ppm and a DIN concentration of 0.3 ppm marine phytoplankton (save cyanobacter) would be P-limited. Marine macroalgae (all the algae we care about as reef aquarists, save perhaps diatoms and dinoflagellates) require more N relative to P. The N stoichiometry for marine macroalgae tends to be closer to 30:1, and can be as high as 45:1 in many cases (actually, the same is true of many phytoplankters--Redfield's ratio applies only as an average composition, especially over time). So, for the algae we care about in reef tanks, at a DIP conc. of 0.03 ppm the DIN would need to be nearer 0.6-0.9 ppm to alleviate N-limitation.
Anyway, IME many if not most reef tanks nowadays pretty consistently fall in the range of undetectable DIN and DIP, or nearly so. If someone has 0.03 ppm DIP and 0.2 ppm DIN, the algae in the tank are definitely N-limited before P-limited.
Of course, none of this is to say that other things cannot limit them. In fact, on reefs it has been shown experimentally many times that herbivory is far more important than background nutrient concentrations in limiting algal growth and biomass, even on some polluted and therefore fertilized reefs. I'll also point out that turf algae species typically cover 10-50% of the substrate on most reefs (more than corals most of the time). As such, it isn't surprising you have algal turfs growing in the tank. What is the herbivore population like? Does anything in your tank eat that algae?
Best,
Chris
Sure, I never said that it was impossible to have a P limited tank in terms of algal growth. In fact, I stated just the opposite...a couple times I think
On reefs in nature algae are always (well, >99% of the time I'll say, to allow for weird situations) N-limited on reefs. In the open ocean near continents phytoplankton tend to be barely N-limited or N and P co-limited. Far from continents they tend to Fe-limited (southern ocean).
So yes, if (for example) a person had a reef tank where the water had a DIP concentration of 0.03 ppm and a DIN concentration of 0.3 ppm marine phytoplankton (save cyanobacter) would be P-limited. Marine macroalgae (all the algae we care about as reef aquarists, save perhaps diatoms and dinoflagellates) require more N relative to P. The N
stoichiometry for marine macroalgae tends to be closer to 30:1, and can be as high as 45:1 in many cases (actually, the same is true of many phytoplankters--Redfield's ratio applies only as an average composition, especially over time). So, for the algae we care about in reef tanks, at a DIP conc. of 0.03 ppm the DIN would need to be nearer 0.6-0.9 ppm to alleviate N-limitation.Anyway, IME many if not most reef tanks nowadays pretty consistently fall in the range of undetectable DIN and DIP, or nearly so. If someone has 0.03 ppm DIP and 0.2 ppm DIN, the algae in the tank are definitely N-limited before P-limited.
Of course, none of this is to say that other things cannot limit them. In fact, on reefs it has been shown experimentally many times that herbivory is far more important than background nutrient concentrations in limiting algal growth and biomass, even on some polluted and therefore fertilized reefs. I'll also point out that turf algae species typically cover 10-50% of the substrate on most reefs (more than corals most of the time). As such, it isn't surprising you have algal turfs growing in the tank. What is the herbivore population like? Does anything in your tank eat that algae?
Best,
Chris
I have not tested iron as the levels detectable by even the best test kits are waaay above the levels that should be found in NSW or an aquarium. Also, all the iron in the world won't matter unless the algae is iron limited. That is, if their growth is already limited by nitrogen levels then adding iron will have no effect.
As for silicate, I haven't tested it in years but only diatom growth will be affected by silicate levels. I monitor that by growth of film on the glass. The GFO will also remove silicate.
The algae I have is coarse, wiry turf on the rocks. Only the urchins are effective at removing it.
Allen
<a href=showthread.php?s=&postid=7094388#post7094388 target=_blank>Originally posted</a> by MCsaxmaster
Marine macroalgae (all the algae we care about as reef aquarists, save perhaps diatoms and dinoflagellates) require more N relative to P. The N
That is an argument for pushing phosphate levels lower and worrying less about nitrate levels so that microalgae would tend to become limited before macroalgae. Of course, from what I've read phosphate limitation is more potentially dangerous for corals than nitrate limitation so that could be "playing with fire" if pushed too far. That comes from the Coral magazine "The Nutrient Limited Aquarium" series- the one you liked so well. Maybe it is completely wrong. I only got the last installment in that series, which you apparently didn't get so you may not be familiar with that particular article.
Allen
My herbivore population:
Z. desjardinii
P. hepatus
Siganus unimaculatus
A. japonicus
Ctenochaetus strigosus
various snails including Turbo, Trochus, Astraea, and collumbellids
a few hermit crabs
2 Diadema urchins.
Only the urchins have any effect on the turf. It previously covered over 70% of the rocks. I put in 4 urchins which have reduced it to about 20%. I have since moved 2 of the urchins as they began doing more damage to corals. Unfortunately since they can't look around and see where the remaining turf is still covering rocks they graze the same rocks over and over again. Because those rocks have less algae they are more likely to nibble the adjacent corals.
Allen
al I only speak of iron because I have seen it first hand in my aquarium when adding iron I got algea. maybe I had enough iron and the boost helped the algea or it was iron limited. isn't it true that many life forms adapt to there environment and use what they can to survive. supports the whole human and virus theories. I don't hold anything I read about reefs as the word or gospel. there are scientists trying to do good and make a living at the same time. so it serves them well to come up with something believeable. just ask ron shimek he has done this many times then when other people try what he said it resulted in complete failure. or at least alot of failure. please understand I am not trying to attack you or anyone else but I am curious about the silicate removal using gfo products. did you actually test silicates before and after or are you going by the manufacturers claims? I am totally interested in how much and how fast it removes silicates. I know they claim it removes some metals and all kinds of stuff these days. I always want to learn more so I can take it all in and chose what works for my tank and what doesn't. at the time I do not run GFO but I have on other tanks in the past and I can't say I ever needed to. I thought the other day I needed to when I tested my po4 at .1 or 1 I can't remember the scale. then I tested again and it was at the bottom of the fastestm scale at like .02. then I took it to my local store and it also came up .02 so I guess I really don't need it since I want as little as possible running .
it's wierd that the turbos and astreas aren't eating the stuff since they are recommended by many popular books and authors for turf algea. I think my friend talked to sprung about it and he recommended turbos and they took right care of it.
I remember a pretty old article showing what tangs eat in the wild and between a kole tang and an atlantic blue tang they ate pretty much everything algea wise. hair, red, blue, green, diatoms you name it one of the 2 ate it. I think the atlantic blue ate more than the kole since my buddy had a kole when he had turf algea.
it's wierd that the turbos and astreas aren't eating the stuff since they are recommended by many popular books and authors for turf algea. I think my friend talked to sprung about it and he recommended turbos and they took right care of it.
I remember a pretty old article showing what tangs eat in the wild and between a kole tang and an atlantic blue tang they ate pretty much everything algea wise. hair, red, blue, green, diatoms you name it one of the 2 ate it. I think the atlantic blue ate more than the kole since my buddy had a kole when he had turf algea.
I have red cyano and some hair algea and my tank tests very low in phosphates, and nitrates by salifert and fastest low kit are both undetectable. just another proven ideal that we know nothing when it comes to the wonders of nature. the red slime grows on a chili coral, on a few pieces of rock and some failry high flow places in my tank. there is absolutely no algea of anykind in some low flow places and then nothing in some high flow areas. as much as I think I learn the more I know absolutely nothing about.
Travis
10 and over club
I have a buddy with a 58 gallon with 2 tiny fish that get fed sparingly every other day. He has always had bryopsis growing in his tank (not taking over but it has always been there). He brought a water sample to test with my Hanna colorimeter and it tested 0.00. We then tested it with a Deltec/Merck test kit and once again it was 0.00. So there is more to algae than a nitrate or phosphate "problem". It is most likely localized nutrient uptake as it catches/traps detritus and allows it to break down where it can be directly absorbed. But that still doesn't explain why the algae comes back after being completely scraped off with a brush... maybe precipitated P in the rocks????
I guess all I'm trying to say is that just because someone might have a little patch of nuisance algae or cyanobacteria does not necessarily mean they have a N or P problem.
Travis
10 and over club
This has been a great discussion so far. From what MCsaxmaster has stated, it sounds like our aquaria are most likely to be N limited. So if we have detectable P, would adding a source of "N only" cause our corals to utilize some of the extra P that is present. If most of our aquaria are N limited, why aren't we all adding a source of N? What will happen if we do add a source of N? Increased growth rates???? Or is it even worth it if we run the risk of making our tanks P limited (more dangerous) by adding too much N?
MCsaxmaster
New member
Wow, so I can tell you guys all have your thinking caps on and also that you're not buying into so much of the hype and myth associated with this hobby. A very big :thumbsup:
Hi Allen,
Most of the algae that we refer to as "microalgae" in the hobby tend to get 'lumped' with macroalgae much of the time. Of course this is not always the case as things like strings of diatoms, dinoflagellates, etc. are all certainly microalgae, but in order to interpret correctly what marine scientists usually mean it would be a closer approximation for reef aquarists to think of phytoplankton as being the equivalent to "microalgae" in scientific terms and just about everything else as "macroalgae." So, things like the countless varieties of "hair alge" as well as turf species are going to tend to gravitate to N ratios in the 20-40 range.
Oh, as it turns out I actually have that whole series. Apparently I just stopped reading them at about the 4th article. I'll see if I can read through it this weekend though. However, if they say that P-limitation is "more dangerous" for corals than N-limitation, I'm very, very suspicious. They had better have some good references to back that up, otherwise I don't see any merit in that statement. To say the least, both would be bad. Based on some work done on zooplankters in the recent past, I'd expect that fast-growing species of corals would be more affected by P-limitation and slower-growing species more affected by N-limitation, though it is probably splitting hair at best.
Gotcha. Well, only so much one can do there This is normal though. When everything refuses to eat an algae, that algae will very often dominate a portion of substrate. Happens in nature too. Many researchers over the years have very seriously suggested that the name coral reef officially be changed to algal reef as it would be more accurate. All I can say is keep nutrients low and use herbivory. One without the other is useless, but herbivory has the final say. e.g., If you put 100 turbo snails in a ten gallon tank, it really doesn't matter a bit what the ambient nutrient conc.s are, there isn't going to be visible algal growth.
Rob,
Iron can and does limit algal growth, especially in very large areas of the southern ocean. In fact, I highly suspect that the algal growth in many reef tanks is iron limited. For example, a tank with 1 ppm nitrate and 0.1 ppm phosphate might have little algae with just a couple of snails. In nature, unless there were more herbivores than this, there would be an algal bloom like none other. I wonder if we might see the same in many tanks with a little chelated iron? Having said that, there are many, many other things that might be limiting this algae. Iron is just on the short list of things to test.
Also, realize that "turf algae" is just a very general descriptor of growth form. It is a bit like saying "plant," as opposed to "tree" or "bush." There are thousands of unrelated turf algae. They just share a few similar adaptions--very palatable but also very fast growing, able to heal from mechanical injury quickly, and able to grow at very low ambient nutrient levels. Maybe a few other qualifiers as well.
Yes, yes, and yes. To say that nutrient levels are just one of many vitally important characteristics determining algae growth is an understatement. Algae grow extensively and often a lot faster in nature than in our aquariums, yet most tanks are at or above the upper limit of natural nutrient concentrations. There is A LOT more too it than just the availability of N and P.
Travis,
Example par excelance!
Absolutely, absolutely, absolutely! Algae grow on reefs--a lot of algae in fact--and that is the system we're trying to duplicate. Now, of course there is such a thing as unhealthy levels of algal growth, but a patch here or there doesn't necessarily mean anything about the health of tank in general.
Well, like I said I'm pretty unsure that P-limitation is in any way worse than N-limitation for corals, much less most any other animals.
Corals can and do utilize DIN (ammonia/nitrate) and DIP (primarily orthophosphate), but they aren't nearly as good at using these as they are at using particulate sources. In fact, corals in general are really bad at using DIP and take it up very slowly. So, I would say that it would probably be a good thing to be getting more N and P into corals and other suspension feeders, but to do this we really need to be looking to the foods we feed them, not at increasing dissolved nutrients. Ever watch a two-year-old eat spaghetti? A little goes in the mouth, but most of it goes everywhere else. That's what corals are like with DIN and especially DIP.
Best,
Chris
Hi Allen,
Most of the algae that we refer to as "microalgae" in the hobby tend to get 'lumped' with macroalgae much of the time. Of course this is not always the case as things like strings of diatoms, dinoflagellates, etc. are all certainly microalgae, but in order to interpret correctly what marine scientists usually mean it would be a closer approximation for reef aquarists to think of phytoplankton as being the equivalent to "microalgae" in scientific terms and just about everything else as "macroalgae." So, things like the countless varieties of "hair alge" as well as turf species are going to tend to gravitate to N
ratios in the 20-40 range.Oh, as it turns out I actually have that whole series. Apparently I just stopped reading them at about the 4th article. I'll see if I can read through it this weekend though. However, if they say that P-limitation is "more dangerous" for corals than N-limitation, I'm very, very suspicious. They had better have some good references to back that up, otherwise I don't see any merit in that statement. To say the least, both would be bad. Based on some work done on zooplankters in the recent past, I'd expect that fast-growing species of corals would be more affected by P-limitation and slower-growing species more affected by N-limitation, though it is probably splitting hair at best.
Gotcha. Well, only so much one can do there
This is normal though. When everything refuses to eat an algae, that algae will very often dominate a portion of substrate. Happens in nature too. Many researchers over the years have very seriously suggested that the name coral reef officially be changed to algal reef as it would be more accurate. All I can say is keep nutrients low and use herbivory. One without the other is useless, but herbivory has the final say. e.g., If you put 100 turbo snails in a ten gallon tank, it really doesn't matter a bit what the ambient nutrient conc.s are, there isn't going to be visible algal growth.Rob,
Iron can and does limit algal growth, especially in very large areas of the southern ocean. In fact, I highly suspect that the algal growth in many reef tanks is iron limited. For example, a tank with 1 ppm nitrate and 0.1 ppm phosphate might have little algae with just a couple of snails. In nature, unless there were more herbivores than this, there would be an algal bloom like none other. I wonder if we might see the same in many tanks with a little chelated iron? Having said that, there are many, many other things that might be limiting this algae. Iron is just on the short list of things to test.
Also, realize that "turf algae" is just a very general descriptor of growth form. It is a bit like saying "plant," as opposed to "tree" or "bush." There are thousands of unrelated turf algae. They just share a few similar adaptions--very palatable but also very fast growing, able to heal from mechanical injury quickly, and able to grow at very low ambient nutrient levels. Maybe a few other qualifiers as well.
Yes, yes, and yes. To say that nutrient levels are just one of many vitally important characteristics determining algae growth is an understatement. Algae grow extensively and often a lot faster in nature than in our aquariums, yet most tanks are at or above the upper limit of natural nutrient concentrations. There is A LOT more too it than just the availability of N and P.
Travis,
Example par excelance!
Absolutely, absolutely, absolutely! Algae grow on reefs--a lot of algae in fact--and that is the system we're trying to duplicate. Now, of course there is such a thing as unhealthy levels of algal growth, but a patch here or there doesn't necessarily mean anything about the health of tank in general.
Well, like I said I'm pretty unsure that P-limitation is in any way worse than N-limitation for corals, much less most any other animals.
Corals can and do utilize DIN (ammonia/nitrate) and DIP (primarily orthophosphate), but they aren't nearly as good at using these as they are at using particulate sources. In fact, corals in general are really bad at using DIP and take it up very slowly. So, I would say that it would probably be a good thing to be getting more N and P into corals and other suspension feeders, but to do this we really need to be looking to the foods we feed them, not at increasing dissolved nutrients. Ever watch a two-year-old eat spaghetti? A little goes in the mouth, but most of it goes everywhere else. That's what corals are like with DIN and especially DIP.
Best,
Chris
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