Nitrates — is my eyeball method crazy?

[KenRexford]

Still chuckling over the new Hanna Checker Nitrate 16-step process to nail nitrates to ridiculous precision, I wonder whether I am nuts here. Once you get to a certain point in stability, nitrate testing seems dumb and pointless. I mean, nuisance algae sucks up the nitrates. Xenia sucks up the nitrates. The Fuge sucks up the nitrates. So, if my nitrates are good, I show no nitrates. If my nitrates are bad, I also show no nitrates. The test kit is too slow to the show.
Instead of shades of blue or orange-yellow, my best gauge of nitrate problems seems to be whether my GHA is recurring, whether my Xenia is having a party or shriveled up like in a winter chill, and whether my Fuge macro is going nuts or just sitting there. Am I crazy?

 

[Randy Holmes-Farley Verified Community Expert]

Too low may be worse than too high. I'd try to ensure there is some nitrate.

 

[KenRexford]

With a 125g tank housing two clowns, four tangs, a fox face, two damsels, two chromis, an engineer goby, and a royal gramma, I cannot imagine 0 nitrates even using Vibrant. Nitrates obviously are generated. I just don’t understand the concept of latent nitrates in the water being tested.

I mean, it seems like this. The more nitrate producers you have, the more nitrate is Produced naturally. As x amount of nitrate is produced, an equal amount of critters and plants suck it up. If the nitrates go up, more critters and plants grow. If nitrates go down, the plants seem to suffer first. When the plants are gone, I could in theory maybe have bacteria grab so much that the good critters suffer, sure. But, that doesn’t seem possible with my number of fish. Sure, the Xenia slow down growth, but Xenia seem best suited for insane nitrate levels. If my Xenia’s are happy, I have gha. If my Xenia are ticked, my tank looks great and everything else is happy.
But I still see no benefit to the testing. The testing checks what is floating around, not intake to uptake.

consider a parallel. Take a tub and fill it with water. Your water level meter on the side shows how much water is in the tub. Ok, now poke a hole in the bottom of the tub. If the water coming through the hose is faster than the draining hole, the water rises until the pressure from the hole equalizes with the water coming from the hose. If you increase the size of the hole, the water goes down unless you get a bigger hose.

the nitrate test seems to measure the water level. But it doesn’t measure the size of the hose (how much nitrates in) nor the size of the hole (how much uptake by corals and Chaeto and gha).

if the coral hole seems to be flowing (the lowest hole) because corals look good, and if the next-up hole — the chaeto — looks ok but just ok, and if the highest hole (gha) seemsclosed up, then why does the level matter? The level seems again to measure how much is not taken up by critters and plants, not how much IS takenup.

if the nitrate production is low, like not many fish, then maybe you need higher levels because the hose is so small?

 

[92Miata]

I don't understand your objections.


High Nitrates tell you the hole in the bottom isn't big enough. No nitrates tell you its too big. You need some water in the tub or everything dies.


And yes, you absolutely can have 0 latent nitrates and phosphates - and it starts killing things.

 

[blasterman]

My own opinion on this.

0 nitrates either means your nitrate is being consumed via an established tank biology (typically older tanks with large coral loads coupled with macro algae export) or your test kit sucks.

I'm a fan of keeping nitrate at trace levels...aka around 5ppm, but no higher. Zero in a young tank is also a problem as we discussed. There's no reason to keep it higher because if it's sitting at 5ppm having more nitrate molecules isn't going to force anything to eat it faster but it can cause nuisance algae issues. Shrooms and palys like high nitrate....so does cyano and hair algae,

~5ppm is typically the first wedge on common test kits. At least the Salifert I use. If it's anything other than that I need to correct. It's either too low, too high, or just right. You don't need more precision for that.

 

[KenRexford]

You can’t truly have 0 nitrates. It is not possible. I cannot imagine how you could kill things with too low of nitrate if you have a lot of nitrate going in.
If I had a 125 gallon tank with one fish, the fish and it’s food would contribute x amount of nitrate, which is not enough for corals, so they would die. Sure.
If I have 20 fish, 20x nitrates are going in, whatever my nitrate “level” says. If 20x nitrates is enough for the corals, and if the corals eat 20x nitrates, then my tank will show 0 nitrates because the corals are so efficient eaters of nitrate. If the corals only eat 15x nitrates, then I will still show 0 nitrates because then green hair algae will grow and eat 5x nitrates. The only way I show any nitrates is if even my GHA can’t keep up. So, no matter what I do, I show 0 nitrates unless I completely abandon my tank.
I can’t Dose nitrates and then check nitrates because, again, GHA sucks it back up and I show 0. Maybe for a week or two until the GHA establishes itself, but then back to 0.
So, my only actual “test” is the eyeball. If I have GHA, I have 0 nitrates, but my nitrates in are too high or I need bacteria to our-compete the GHA. If my GHA is gone, then my nitrates are not too high, with again 0. I then eyeball the Xenia for whether it is too low.
I don’t understand how anyone is getting anything but 0 nitrates after the tank stabilizes. I just can’t get anything but 0. If I got the Hanna low-level checker, I might show some low figure, but that also seems pointless. It just tells me the rate of uptake, in a sense. The size of the hose, in my example, which is not useful. The only thing it would tell me is how many fish and corals I have.
If I have one fish feeding one coral, my micro-level might be stabilized at, say, 1. The flow of nitrates from fish to coral does not increase because 1 out and 1 in. If I add 4 fish and 4 corals, my nitrates might stabilize at 5, because 5 in 5 out. But the level stays the same if there is equilibrium. At the lowest levels, these numbers are small, like below 5. Only if I have too much in should nitrates be noticed on anything normal. So, if I check micro-levels, it seems that I am only checking how many fish and corals that I have.
Granted, if the level should be say 0.5 but shows 0.4, then the corals might be sucking up nitrates too fast. But, I cannot know the correct level Should be 0.5 because the fish and corals won’t tell me. The best I could do is to assume a slight tendency to slowly increase the micro-numbers over time, as the fish and corals both grow bigger, but that’s wild guesswork, less reliable than the eyeball imo.

 

[MabuyaQ]

You can’t truly have 0 nitrates. It is not possible. I cannot imagine how you could kill things with too low of nitrate if you have a lot of nitrate going in.
If I had a 125 gallon tank with one fish, the fish and it’s food would contribute x amount of nitrate, which is not enough for corals, so they would die. Sure.
If I have 20 fish, 20x nitrates are going in, whatever my nitrate “level” says. If 20x nitrates is enough for the corals, and if the corals eat 20x nitrates, then my tank will show 0 nitrates because the corals are so efficient eaters of nitrate. If the corals only eat 15x nitrates, then I will still show 0 nitrates because then green hair algae will grow and eat 5x nitrates. The only way I show any nitrates is if even my GHA can’t keep up. So, no matter what I do, I show 0 nitrates unless I completely abandon my tank.
I can’t Dose nitrates and then check nitrates because, again, GHA sucks it back up and I show 0. Maybe for a week or two until the GHA establishes itself, but then back to 0.
So, my only actual “test” is the eyeball. If I have GHA, I have 0 nitrates, but my nitrates in are too high or I need bacteria to our-compete the GHA. If my GHA is gone, then my nitrates are not too high, with again 0. I then eyeball the Xenia for whether it is too low.
I don’t understand how anyone is getting anything but 0 nitrates after the tank stabilizes. I just can’t get anything but 0. If I got the Hanna low-level checker, I might show some low figure, but that also seems pointless. It just tells me the rate of uptake, in a sense. The size of the hose, in my example, which is not useful. The only thing it would tell me is how many fish and corals I have.
If I have one fish feeding one coral, my micro-level might be stabilized at, say, 1. The flow of nitrates from fish to coral does not increase because 1 out and 1 in. If I add 4 fish and 4 corals, my nitrates might stabilize at 5, because 5 in 5 out. But the level stays the same if there is equilibrium. At the lowest levels, these numbers are small, like below 5. Only if I have too much in should nitrates be noticed on anything normal. So, if I check micro-levels, it seems that I am only checking how many fish and corals that I have.
Granted, if the level should be say 0.5 but shows 0.4, then the corals might be sucking up nitrates too fast. But, I cannot know the correct level Should be 0.5 because the fish and corals won’t tell me. The best I could do is to assume a slight tendency to slowly increase the micro-numbers over time, as the fish and corals both grow bigger, but that’s wild guesswork, less reliable than the eyeball imo.

You are right but the problem is you never know who consumed the nitrate produced so you want to make sure there is enough at all times for everybody. So you don't want it to close to zero when measured. Between 2 and 5 ppm is best in my opinion.

 

[Deep]

consider a parallel. Take a tub and fill it with water. Your water level meter on the side shows how much water is in the tub. Ok, now poke a hole in the bottom of the tub. If the water coming through the hose is faster than the draining hole, the water rises until the pressure from the hole equalizes with the water coming from the hose. If you increase the size of the hole, the water goes down unless you get a bigger hose.

In your bath tub and holes analogy - you actually need 3 holes to properly explain this. One hole for nutrients consumed by your corals, another hole is what is consumed by your pest algae, one more hole for nutrient export. So if you have zero nutrients in your water column, it could also be that your nutrient export hole and algae hole are taking away all your nutrients leaving nothing for the corals. The only way you can ensure this does not happen is by having some trace nutrients ( maybe 4-5 ppm ?) in your water column. Otherwise you have no way of knowing. So thats why the test is useful.

 

[Thaxxx]

In your bath tub and holes analogy - you actually need 3 holes to properly explain this. One hole for nutrients consumed by your corals, another hole is what is consumed by your pest algae, one more hole for nutrient export. So if you have zero nutrients in your water column, it could also be that your nutrient export hole and algae hole are taking away all your nutrients leaving nothing for the corals. The only way you can ensure this does not happen is by having some trace nutrients ( maybe 4-5 ppm ?) in your water column. Otherwise you have no way of knowing. So thats why the test is useful.

That's a good point.
My question has always been, if your nutrients are too low and you export with mechanical filtration, a skimmer and a fuge. Why do people dose nitrate products before they try turning off skimmer, removing filter socks, and cutting out there fuge for some time, and see if their nitrates come up?

 

[92Miata]

Why wouldn't they?

Dosing is consistent and predictable. And you can immediately test the results.

I'm a feed heavy person - but it's often difficult to predict what the results are going to be - and corals die pretty quickly when you start actually bottoming out. So it's often safer to just start dosing when there's a problem.

 

[KenRexford]

In your bath tub and holes analogy - you actually need 3 holes to properly explain this. One hole for nutrients consumed by your corals, another hole is what is consumed by your pest algae, one more hole for nutrient export. So if you have zero nutrients in your water column, it could also be that your nutrient export hole and algae hole are taking away all your nutrients leaving nothing for the corals. The only way you can ensure this does not happen is by having some trace nutrients ( maybe 4-5 ppm ?) in your water column. Otherwise you have no way of knowing. So thats why the test is useful.

I think this is wrong for one rather simple experience reason. GHA and other bad algae cause false 0 readings on test kits. Nitrate/Phosphate export strategies kills GHA and bad algae before corals. Therefore, two conclusions seem unavoidable.
First, the bad algae hole is higher in the barrel.
Second, as bad algae falsifies test results, testing does not work.
Again, if one fish is in a tank with one coral exactly matching in uptake the nitrate/phosphate contribution of the fish, then the amount of nitrate in the system is that amount present when it passes from the fish to the coral. Multiply the fish and coral by 20 and you raise that background level by 20 but have no or little impact on excess for the less worthy bad algae. The example breaks down with one fish and coral in a large tank, obviously, but the principle should work for a well-stocked, well-balanced tank if my thinking is right. My actual experience and those implied by anyone using export reduction methods like a refugium, gfo, carbon dosing, etc., is just that — you end up with test results on, say, normal testing methods that seem to be ULN Systems unless you then use a precise test like this new Hanna Checker 0-5 testing. But that 0-5 result keeps seeming pointless, other than to gauge your tank inhabitant density, which seems like useless information. The only thing I could see value in might not be the precise level, as that should slowly increase as the tank matures, but rather maybe if a radical change happened, which might suggest that something died, where maybe a water change and looking for the dead critter might make sense to avoid a temporary algae bloom.

 

[jccaclimber]

1. I dislike the "fish cause nitrates" analogy. Fish do not cause nitrates. Putting things with nitrogen (such as fish food), and then not consuming or exporting them causes nitrates. My fish are fat and happy, but I could double my food input if I wanted to, and my nitrate levels would go up, I'd just have a bit more food rotting in the tank, a larger bristleworm population, whatever. I could probably likewise cut it in half without any major consequences.
2. I have personally seen, and corrected, many tanks that were nitrate starved. I've also seen many tanks reading 0 nitrates that are thriving. I tend to like explaining it like cashflow. Say your expenses (rent, food, fish tanks, everything) are $100/month (yeah, we wish) and your income is $100/month, nothing changes. Now, consider these 4 cases:

Case 1, Nitrates too high
If your income is $200/month you would quickly build up savings (nitrates in this case). Pretty soon you have so much that your cousin Mooch (excess algae) comes along because he senses the opportunity. Your bills get paid, but other expenses seem to come up as a result of having that money around.
Case 2, Nitrates barely in surplus
Now your monthly income is $100.01. Your bills all get paid. In theory you would develop savings (measurable nitrates) over a long time, but if whatever the financial equivalent of a water change is comes along it'll be back to 0 and it'll never show up on a test kit.
Case 3, Nitrates barely deficient.
This time your monthly income is $99.99. In theory you are running short, but people find a way. Maybe you wait a day to go grocery shopping or post-date your rent check by a day. You go just a bit hungry, but it isn't obvious. The bills get paid and things carry on.
Case 4, Nitrates severely deficient.
Now your monthly income is $50. Rent does not get paid, or you aren't going to the grocery store. Thing go wrong. You get sick from malnutrition, or end up without a roof over your head each night. The tank equivalent to this is pale corals and STN issues that seemingly pop up at random while other corals do ok.

You can't really tell case 2 from case 3, and it doesn't matter a lot. It is easy to tell the rest apart though.
Tanks in Case 1 have high nitrates, and those nitrates increase without water changes.
Tanks in Case 2, Case 3, and Case 4 all look the same, zero nitrates on a hobbyist test kit. Note that if we're talking an API kit you may well be running around 1-2 PPM (ie Case 2) and be getting a false zero on the test kit. Now, dose some nitrate, say 5 PPM. In a week if you have zero nitrates then your tank consumed it, and you're pushing towards Case 4 and your tank is hungry. If you still have 5 PPM then you're either Case 2 or Case 3. So long as your demand does not increase you're fine.
If you don't have a nitrate source on hand you can also simply increase your feeding.

As for the eyeball method, if it works for you then go with it. Personally I've seen a lot of systems where the owner thinks its doing great (and it does look nice), but then when we increase the nitrate level just a bit suddenly the coral grows faster. Specific example, I knew a guy with a beautiful SPS reef. After talking to him I discovered that his 4" SPS colonies were 5 years old, grown from frags. The same coral grew to that size in a year in my tank from the same size frag. He was nitrate starved, didn't realize it, and had been able to handle the mild side effects without noticing.

 

[KenRexford]

OK, let me see if I understand correctly. The normal test kits may very well be somewhat useless in telling me if I have too much in the way of nitrates, because I will 0 out not matter what I do, due to algae masking any increases. However, if I use a more precise test kit, I also might initially get a number that is perhaps somewhat useless unless it reads exactly 0 also, in which case very well might be running too low. So, I then dose a bit of nitrate and check. If I stay at 0, I am starved for nitrates. So, maybe I dose more and check again. When I get to a slight increase, I dial back a smidge and maintain at that level of barely reading but present. I might check periodically to see if I dropped back to 0 (or went the other direction), and adjust accordingly.

I see the potential benefit, but maybe I am operating off of a less than ideal system or a different kind of system. I always have a smidge of algae. No matter how heavily I export, the difference seems to be whether I have outbreaks or mere occasional smudges to remove. If all is well, I have occasional smudges. It still seems to me that perhaps for my tank and husbandry the eyeball test remains as effective, because I never completely 0 out or at least cannot imagine that a very technical test would show 0. I could never imagine getting to so devoid of nitrates that all algae dies. With a refugium with macro-algae, the macro-algae would be suffering from true 0, I would think. If a tank had no refugium to assess and no sign of any smudges of algae, I guess it might be barely functioning with nearly complete 0 and undetectable nitrates due to heavy protein skimming and GFO and carbon dosing all wreaking havoc on any nitrates that manage to sneak through, then I guess the test kit for extremely low levels makes sense. But, if the system has a refugium, the macro-algae is either thriving or not. If it is thriving, then there cannot be complete depletion. If the smudge is not growing, and if the GHA stumps are dying, then that seems like as good of an equlibrium test as technical numbers on any test kit.

 

[jccaclimber]

If you're at zero (or whatever close enough to zero is in our case), then yes, test kits are useless. Some however are worse than others. For example, if I'm happily running around 2 PPM (very different than a hard deficit) then my Red Sea test will read 2 PPM (and without the 27 step Hanna process), but my API test will read zero (well, some kits will read zero, some will read a bit of color, they aren't consistent).

To an extent I'm using nitrate as a proxy for available nitrogen to corals, although the two are not the same.
Two important points here:
1. If we're talking just free nitrogen as nitrate in the water column your coral will starve before your algae. I've had my coral grow pale with some pieces STNing and others growing very slowly. The algae was doing just fine the entire time. By the time you truly starve the algae, the coral will starve too. The same is true in freshwater planted systems, the plants starve before some forms of algae.
2. There are other nitrogen sources for your coral that the algae may not benefit from. I'm starting to talk beyond my knowledge here, so someone may need to leap in and correct me. Something like phyto or waterborne bacteria might serve as a food and therefore nitrogen source for the coral, but be unavailable to the algae. This also won't show up on a test kit. Unfortunately, shy of the eyeball method (which has a lot of underlying assumptions) we don't have a good hobbyist friendly way to test this. If you have a system with a ton of these other sources you may well read 0 free nitrate and still have very happy coral. However IME if you run too much of a nitrate shortage the rest of the food chain will eventually collapse. All that phyto/bacteria/whatever has to come from somewhere.

I don't understand how your algae "masks" an increase. It is a consumer, nuisance or macro, just like your coral, sand bed bacteria, etc. As to if the algae or the coral is better at utilizing your nitrogen sources is a different discussion. Based on my observations that I've seen coral starve and die with algae present in the tank, and seen the same thing with plants vs. algae in freshwater systems I'm inclined to say the algae is better at low nutrient values.

I agree that knowing that your macro is thriving is certainly a good start to knowing that you aren't running a hard deficit. There's more to it though as I've had systems where the macro thrives (half a 5 gallon bucket per week) yet the coral later responded very well to nitrate dosing. I've also had systems where the macro is stagnant, yet nitrate is present and the coral is doing well. What became the limiting item in that case I don't know.

 

[jccaclimber]

Something to put in here, if you know your system and have a good feel for it, you might not gain much of a benefit.
I on the other hand once a year or so have a problem I can't ID, I start testing, I find something to be way off, I correct it, and things trend in a better direction. I don't do a full bank of tests regularly as I've found some parameters to change faster than others. I frequently test the things that require frequent adjustment, and infrequently test the things that never seem to be off, aren't important, etc.

I happen to dose nitrate. When I'm starting up, make a major change, etc. then I test frequently. Once it stabilizes I back off and test perhaps monthly. During that initial tuning stage as I'm trying to determine a consumption rate a more accurate and precise test would be useful as I would be able to dial in the system faster.

 

[MabuyaQ]

OK, let me see if I understand correctly. The normal test kits may very well be somewhat useless in telling me if I have too much in the way of nitrates, because I will 0 out not matter what I do, due to algae masking any increases. However, if I use a more precise test kit, I also might initially get a number that is perhaps somewhat useless unless it reads exactly 0 also, in which case very well might be running too low. So, I then dose a bit of nitrate and check. If I stay at 0, I am starved for nitrates. So, maybe I dose more and check again. When I get to a slight increase, I dial back a smidge and maintain at that level of barely reading but present. I might check periodically to see if I dropped back to 0 (or went the other direction), and adjust accordingly.

I see the potential benefit, but maybe I am operating off of a less than ideal system or a different kind of system. I always have a smidge of algae. No matter how heavily I export, the difference seems to be whether I have outbreaks or mere occasional smudges to remove. If all is well, I have occasional smudges. It still seems to me that perhaps for my tank and husbandry the eyeball test remains as effective, because I never completely 0 out or at least cannot imagine that a very technical test would show 0. I could never imagine getting to so devoid of nitrates that all algae dies. With a refugium with macro-algae, the macro-algae would be suffering from true 0, I would think. If a tank had no refugium to assess and no sign of any smudges of algae, I guess it might be barely functioning with nearly complete 0 and undetectable nitrates due to heavy protein skimming and GFO and carbon dosing all wreaking havoc on any nitrates that manage to sneak through, then I guess the test kit for extremely low levels makes sense. But, if the system has a refugium, the macro-algae is either thriving or not. If it is thriving, then there cannot be complete depletion. If the smudge is not growing, and if the GHA stumps are dying, then that seems like as good of an equlibrium test as technical numbers on any test kit.

Algae are a given in any reef without the right and right number of algae eaters. They outcompete almost anything for nutrients. In a stable high nutrient flow through system that a well established reef is you can work with low nutrient levels. But I wouldn't just rely on animal signals when close to the edge because false positives and false negatives are a given at some point. You would want to see this backed by (trends in) testresults.

 

[Jon Fishman]

I haven’t tested anything other than salinity in over a year....... so I say eyeball away

 

[MnFish1]

With a 125g tank housing two clowns, four tangs, a fox face, two damsels, two chromis, an engineer goby, and a royal gramma, I cannot imagine 0 nitrates even using Vibrant. Nitrates obviously are generated. I just don’t understand the concept of latent nitrates in the water being tested.

I mean, it seems like this. The more nitrate producers you have, the more nitrate is Produced naturally. As x amount of nitrate is produced, an equal amount of critters and plants suck it up. If the nitrates go up, more critters and plants grow. If nitrates go down, the plants seem to suffer first. When the plants are gone, I could in theory maybe have bacteria grab so much that the good critters suffer, sure. But, that doesn’t seem possible with my number of fish. Sure, the Xenia slow down growth, but Xenia seem best suited for insane nitrate levels. If my Xenia’s are happy, I have gha. If my Xenia are ticked, my tank looks great and everything else is happy.
But I still see no benefit to the testing. The testing checks what is floating around, not intake to uptake.

consider a parallel. Take a tub and fill it with water. Your water level meter on the side shows how much water is in the tub. Ok, now poke a hole in the bottom of the tub. If the water coming through the hose is faster than the draining hole, the water rises until the pressure from the hole equalizes with the water coming from the hose. If you increase the size of the hole, the water goes down unless you get a bigger hose.

the nitrate test seems to measure the water level. But it doesn’t measure the size of the hose (how much nitrates in) nor the size of the hole (how much uptake by corals and Chaeto and gha).

if the coral hole seems to be flowing (the lowest hole) because corals look good, and if the next-up hole — the chaeto — looks ok but just ok, and if the highest hole (gha) seemsclosed up, then why does the level matter? The level seems again to measure how much is not taken up by critters and plants, not how much IS takenup.

if the nitrate production is low, like not many fish, then maybe you need higher levels because the hose is so small?

If you think about it - using your logic - nitrate would always be 'zero'. Because - if as you say excess nitrate is consumed - if everything was in balance - even a 'trace' of nitrate would be consumed and the nitrate would be 'zero'. Additionally - there are plenty of tanks that have much higher levels of nitrates than 'trace' - that do not have excess algae, etc - because Nitrate is not the only limiting factor for (for example GHA) growth. So - While I agree with you in general - I still test once a month or so - just to see if my water change regimen is 'working'. Do I think one needs to know if the nitrate is 5 or 5.5 - no.

 

[MnFish1]

Algae are a given in any reef without the right and right number of algae eaters. They outcompete almost anything for nutrients. In a stable high nutrient flow through system that a well established reef is you can work with low nutrient levels. But I wouldn't just rely on animal signals when close to the edge because false positives and false negatives are a given at some point. You would want to see this backed by (trends in) testresults.

On the reef nitrate is extremely low - yet there is algae. How?

 

[Randy Holmes-Farley Verified Community Expert]

My question has always been, if your nutrients are too low and you export with mechanical filtration, a skimmer and a fuge. Why do people dose nitrate products before they try turning off skimmer, removing filter socks, and cutting out there fuge for some time, and see if their nitrates come up?

Because skimmers do far more useful things that control nutrients. I would run one for aeration alone.