Experiment: Trace Element Limitation in Reef Tank?

[Randy Holmes-Farley]

In my latest triton ICP my Si levels are low 21ug/l against the setpoint of 100ug/l is Si important as I read Taricha monitoring it? I keep an SPS reef.
Thank you all for posting the articles and comments, I must admit a lot of it goes over my head, but I may get it one day and it’s great to have the articles for reference

No SPS coral has any use for silica. Sponges, snails, diatoms, and some soft corals do.

 

[Ardeus]

Red Sea has tied the consumption of a variety of elements to the calcium consumption and yet for some reason, they take ULN tanks out of the equation. They are confident enough to recommend the dosing of their "color program" to all other tanks based solely on calcium consumption.

Has this connection been established by anyone else as a general rule that applies to all reef tanks? Why doesn't it apply to ULN tanks?

 

[Randy Holmes-Farley]

Has this connection been established by anyone else as a general rule that applies to all reef tanks? Why doesn't it apply to ULN tanks?

In the extreme, it is obvious that this is a bad idea. Suppose you have all soft corals and anemones and lots of macroalgae taking up the nutrients released from feeding lots of fish. You might have very little calcification and hence very little demand for calcium,a nd yet a huge demand for trace elements.

Since most reef tanks are on a continuum between this extreme and an all hard coral tank, some will fit their plan better than others.

 

[Ardeus]

But in the situation you described at least the only risk would be underdosing trace elements.

Can you see a scenario where following their directions of tieing the dosage of trace elements to calcium consumption would result in overdosing with long term use?

One could always try to prevent such problems with a couple of ICP tests per year, although the ICP tests don't seem to be completely reliable.

Given that one of the critical factors for success in keeping reef tanks healthy is stability, chasing values based on unreliable tests seems a bad option.

 

[Randy Holmes-Farley]

But in the situation you described at least the only risk would be underdosing trace elements.

Can you see a scenario where following their directions of tieing the dosage of trace elements to calcium consumption would result in overdosing with long term use?

One could always try to prevent such problems with a couple of ICP tests per year, although the ICP tests don't seem to be completely reliable.

Given that one of the critical factors for success in keeping reef tanks healthy is stability, chasing values based on unreliable tests seems a bad option.

Well, many people have elevated levels of certain trace elements without dosing, so those people will make a problem worse, but in general, I suspect that dosing a name brand trace element mix, either in relation to calcification or just based on gallons, won't, by itself, cause a toxicity problem.

 

[Ardeus]

Thanks for helping me decide what to do.

I will get an ICP test to start with, and according to the results, I will see if it's worth to proceed with dosing trace elements and if yes, at which dose.

 

[MacSakkie]

Wow, and to think we sending people to Mars...

 

[Randy Holmes-Farley]

Wow, and to think we sending people to Mars...

I don't know if we will be sending people any time soon, but my brother is the Lead Scientist on the 2020 Mars Rover expedition.

 

[taricha]

I ran some N & P numbers on food inputs and do any of these sound crazy?
3gram cube of mysis
25 mg N 0.3 mg P
ppm in a 70gal system
0.42ppm NO3 0.0035ppm Po4

3gram cube of brine shrimp
15mg N 2.2mg P
ppm in a 70gal system
0.25ppm NO3 0.025ppm Po4

3gram cube of cyclops
9%N 1.5%P (of dry weight)
9% dry weight
24mg N 3.9mg P
...in a 70gal system
0.40ppm No3 0.045 ppm PO4

3gram cube of daphnia
9%N 1.5%P (of dry weight)
11% dry weight
29.7mg N 4.9mg P
...in a 70gal system
0.50ppm NO3 0.056ppm PO4

So if I feed 1 cube of mysis + 1 cube of something else, I get a daily food input of around
40-55mg N, and 2.5-5.5mg P
0.7-0.9ppm NO3 and 0.03-0.06ppm PO4

This seems reasonable to me because my exports average around 30g chaetomorpha a day, which if the numbers are around those cited for caulerpa here, then I'm exporting about 30mg of N and 2.4mg of P per day through chaeto. So it might be very wrong but nice to see the food inputs and algae exports around the same scale.

 

[Hans-Werner]

Red Sea has tied the consumption of a variety of elements to the calcium consumption and yet for some reason, they take ULN tanks out of the equation. They are confident enough to recommend the dosing of their "color program" to all other tanks based solely on calcium consumption.

I do not know why Red Sea does state this. I think a trace element dosage adjusted to calcium consumption will also take coralline algae into consideration. The trace elements consumption of coralline algae is higher than trace elements incorporation through calcification of scleractinians. At very low nutrient concentrations coralline algae are amongst the first ones which stop growing. Also other organisms which do not calcify very much or do not calcify at all might consume some trace elements at higher nutrient concentrations. In this way trace elements consumption is higher at higher nutrient levels.

This theory is in sharp contrast to the theory that enough trace elements are added with food. It would mean that feeding causes a further trace elements consumption that is not satisfied by the food.

 

[Ardeus]

At least it seems that tieing the consumption of trace elements to calcium consumption only runs the risk of not supplying enough trace elements and not the opposite.

I only dose kalkwasser with vinegar and I'm going to do my first ICP test in a few days and I am curious about the trace elements results.

I never dosed anything else because, as you say, I was counting on the feedings and water changes to be able to keep most of the other elements at acceptable levels.

 

[Randy Holmes-Farley]

I ran some N & P numbers on food inputs and do any of these sound crazy?
3gram cube of mysis
25 mg N 0.3 mg P
ppm in a 70gal system
0.42ppm NO3 0.0035ppm Po4

3gram cube of brine shrimp
15mg N 2.2mg P
ppm in a 70gal system
0.25ppm NO3 0.025ppm Po4

3gram cube of cyclops
9%N 1.5%P (of dry weight)
9% dry weight
24mg N 3.9mg P
...in a 70gal system
0.40ppm No3 0.045 ppm PO4

3gram cube of daphnia
9%N 1.5%P (of dry weight)
11% dry weight
29.7mg N 4.9mg P
...in a 70gal system
0.50ppm NO3 0.056ppm PO4

So if I feed 1 cube of mysis + 1 cube of something else, I get a daily food input of around
40-55mg N, and 2.5-5.5mg P
0.7-0.9ppm NO3 and 0.03-0.06ppm PO4

This seems reasonable to me because my exports average around 30g chaetomorpha a day, which if the numbers are around those cited for caulerpa here, then I'm exporting about 30mg of N and 2.4mg of P per day through chaeto. So it might be very wrong but nice to see the food inputs and algae exports around the same scale.

Where did you get the N values from?

 

[taricha]

Where did you get the N values from?

I used the protein data from the phosphate and math article, and the questionable estimation of protein x 16% = N (for mysis and brine)
For daphnia I found a paper that looked at C,N,P vs dry weight - their average was like 9% N, and 1.47% P.
A separate paper had cyclopoids at the same 1.5% P of dry weight, so I guessed N was similar.

 

[Randy Holmes-Farley]

I used the protein data from the phosphate and math article, and the questionable estimation of protein x 16% = N (for mysis and brine)
For daphnia I found a paper that looked at C,N,P vs dry weight - their average was like 9% N, and 1.47% P.
A separate paper had cyclopoids at the same 1.5% P of dry weight, so I guessed N was similar.

OK, thanks. That conversion is likely the best we can get.

 

[taricha]

no fireworks yet, but let's look at some graphs, shall we?
First, overall tested levels of NO3, PO4, and Si

The recent drop in NO3 is from me reducing dosing after I got more accurate measurements and realizing I can re-adjust my target NO3.

Next is mostly the same data but with daily inputs shown as well to put the variations in test values in context. The system's elastic consumption of silica is quite remarkable.

and finally Ca, Alk, and pH.

I'll talk in more depth about some observations later, but so far my lesson is that I have to tighten up my observations if I'm going to demonstrate what I want to show.
because nothing in my notes could explain the cause of the calcium event (drop 425-380) from days 11,12,15 - that you can also see mirrored in the PO4 data.
No explanation for its smaller cousin between days 21-22 (390 to 360 double-checked those measurements).

 

[taricha]

Ok. So I had a little hiccup with my DIY cryptic 5gal bucket. Lesson: if a container is not designed with seals to hold water under pumping pressure, then trying to DIY the seals to handle it will never be secure. 3 fails is enough for me to get the point. :-(
So gonna have to reset some things and restabilize before any further useful data could be had.
Also going to tighten things up with regards to a few measurements, and more complete documentation in personal notes to give me a better chance of tracking source of any changes.....

In the mean-time I want to circle back to this idea...

You may be able to come up with some interesting results by following this path of "consumption imbalance", but they can be difficult to observe. Most often, when a macroorganism suffers from limitation of an essential nutrient, what occur are developmental delays and some "deficiency diseases", but not necessarily rapid death. For microscopic beings, if a limiting factor causes some to die, their bodies will supply nutrients to the others.

This is very interesting because it matched my assumptions going into it - that seeing chemical evidence of limitation through behavior of tested parameters would be more clear than visual changes in the populations of the tank.

I now think this is wrong though.

While the nutrient evidence of limitations to various organisms during this 3 weeks was hard to see from the data I've posted, some population changes were quite clear.
1. cyanobacteria increase/retreat/disappearance

Pics on day 2, 4, 6 & 10. Cyano never reappeared.

2. Cryptomonas/Rhodomonas disappearance and slight reappearance
Along with the cyano is a tiny protist dude that matches cryptomonas/rhodomonas description.
They were abundant pre-test Mar 23 through Apr 3 (Day 4).
video from that day.

after cyano disappeared, they were entirely absent from sand sampled in the same area on Day 15. They make a reappearance on Day 24 - see sand pigmentation discussion below.

3. Diatom increase, decrease, reappearance
Diatoms increased with silica addition early on, then plateaued, and surprisingly a glass scraping on day 15 showed diatoms had been almost entirely replaced by a mix of green algae, coralline, and a brown film algae - sand samples on the same day showed diatoms to be nearly totally absent there as well. Then they reappeared in force on the glass - Day 24 a scraping was totally diatoms.
This is hard to tie to nutrients because the silica consumption was basically steadily increasing with the increasing dose throughout the whole time frame.

Top 2 - Day 4 diatoms likely at their peak. Bottom 2 - Glass scraping Day 15.

Day 24 - glass film makes a comeback and is near 100% diatoms again.

4. Algae growth.
While hard to quantify, I'd say green algae growth in the display may have stalled/declined for the bulk of the experiment.
Below is a derbesia plug on 3/23 (pre-test), and Days 3,4,6&8

(I never saw signs of a slowdown in the chaeto in the sump.)

5. Sand pigmentation:
Some color to the sand pre-test decreased during the test and stayed as white as I can ever recall it for the bulk of the test with a slight resurgence of brown pigments in the sand by Day 24.

Mar 20 (Pre-Test), Apr 1 - Day2, Days 6,10,19,24.
Inspection of pigmented sand patch on Day 24 showed lots of benthic diatoms, some of the cryptomonads, and a few dinoflagellates.
scope video:


6. Sponges
While I can't say anything conclusively about growth, on day 6 my orange tree sponge opened its siphons showing normal feeding behavior for the first time in many weeks. It had been a long slow degradation process up to that point. (Not 100%, but I think for the last few days - Day 20+ it's been closed again.)

So all that said - I think from the data I do have - I could make a more convincing case for growth limitations in my system by actual observation of the organisms than analysis of the nutrient tests.

Why might that be?
Maybe because to see a sharp drop in consumption of Major nutrients - N, P or Si - in a system that has many classes of organisms that use it - all or nearly all of those organisms would first have to hit a limitation or co-limitations of several scarce resources. If only a few organisms are limited, there are still others that can cover that up by their continued consumption.
For instance: diatom population dropped in the middle of the test with no noticeable decrease in Si consumption - actually Si consumption was still rapidly increasing. Apparently sponges in my system were more than capable of picking up the slack.

 

[Hans-Werner]

Why might that be?

If you are testing you only will find the surplus of nutrients that are not consumed. Watching the behavior of livestock says more about effect and consumption of nutrients than testing.

 

[taricha]

Question. Could the use of Prime water conditioner (say a ml or so) have any effect on the availability of some metals?
"Detoxifies heavy metals" means it binds them to keep them away from biological processes?

 

[mcarroll]

Based on that it seems like the answer ought to be "yes". But I don't know for sure either.

 

[Jose Mayo]

Question. Could the use of Prime water conditioner (say a ml or so) have any effect on the availability of some metals?
"Detoxifies heavy metals" means it binds them to keep them away from biological processes?

Prime is based on hydrosulfites, it is a chemical reducer, not a chelator. Its effect is short-lived, perhaps no more than two days ... it is excellent in an emergency, but not as heavy metal remediation.

Regards