Ammonium dosing is a bit overrated

[Randy Holmes-Farley Verified Community Expert]

Can the Zooxanthellae inside the coral also excrete organic carbon to the water column?

That would explain why my last tank that was NO3 limited (was very challenging to change from 0) had high DOC despite me dosing any form of carbon and doing good husbandry (water changes, good skimmer etc)

What tool and target values said DOC was high?

What does “ nitrate limited” mean to you?

I don’t think the photosynthesis products will accumulate in a reef tank as they are very rapidly metabolized.

 

[Dan Reef]

It went from 1.5mg/l to 4.5mg/l, according to Triton N-DOC

Limit = 0 on Hanna HR

 

[Dburr1014]

Every instance I have had of a dinoflagellate bloom has been linked to flashing zeros on my Hanna eggs. I can always tell when PO4 is getting too low in my display because my rainbow monti starts retracting polyps in the center. Probably a an evil plot coordinated by Hanna to sell more reagent!

Haven't been on much lately and 14 pages in a week is evidence.
I would like to say that I can't disagree with what you are saying but I do think that the zero po4 is more likely why you end up with dino's rather than the zero no3.

I have not seen any evidence than some po4 and zero no3 ends up with dino's. I have seen it the other way, zero po4 some no3.

If anyone has evidence, I'd love to read it.

 

[Randy Holmes-Farley Verified Community Expert]

It went from 1.5mg/l to 4.5mg/l, according to Triton N-DOC

Limit = 0 on Hanna HR

I’m not understanding what you mean. Those are N-doc values when doing what?

I also do not know what the last sentence means.

 

[rtparty]

Haven't been on much lately and 14 pages in a week is evidence.
I would like to say that I can't disagree with what you are saying but I do think that the zero po4 is more likely why you end up with dino's rather than the zero no3.

I have not seen any evidence than some po4 and zero no3 ends up with dino's. I have seen it the other way, zero po4 some no3.

If anyone has evidence, I'd love to read it.

100% anecdotal but in my 250 I had little patches of sand dwelling dinos start popping up and when tested my nitrate was 0 and phosphate was like .2 or .4. I don't recall exacts on PO4. This caught me off guard because my 250 routinely ran high nitrates for months and months.

I started dosing ammonia according to Randy's thread and almost overnight the dino patches were smothered in cyano and then disappeared shortly after.

I think I put pics in Randy's thread to document it all but don't remember

 

[Dan Reef]

I’m not understanding what you mean. Those are N-doc values when doing what?

I also do not know what the last sentence means.

Sorry for the confusion. I mean I sent my water to Triton to test 2 times (3 month difference) from each test. The first resulted in 1.5mg/l "organic carbon". The second resulted in 4.5mg/l and, according to their analysis, that number is a bit high.

When testing for NO3 using Hanna Nitrate High Range, the result was 0.

I just thought that algae was not been able to grow, as Hans said, and was possibly excreting DOC. Just a guess.

 

[jeremie]

I guess the important question is, assuming this hypothesis is even true, is it detrimental?

The last paragraph, if correct as literally written, suggests it is not true for elevated nitrate, and seems to suggest the hypothesis in the first paragraph is not actually happening (extra N caused proliferation instead of transfer).

I don't think there's a simple answer here, and it might also depend on how one defines a healthy coral.

There are certainly other mechanisms that can shift the carbon balance of the holobiont, so even if the hypothesis is true, its impact may be masked by other factors.

Some studies also suggest that corals might be able to regulate the release of photosynthates from zooxanthellae with certain signaling molecules. However, most experiments were done in vitro, so whether these molecules work the same way in hospite is still a question.

 

[Randy Holmes-Farley Verified Community Expert]

Sorry for the confusion. I mean I sent my water to Triton to test 2 times (3 month difference) from each test. The first resulted in 1.5mg/l "organic carbon". The second resulted in 4.5mg/l and, according to their analysis, that number is a bit high.

When testing for NO3 using Hanna Nitrate High Range, the result was 0.

I just thought that algae was not been able to grow, as Hans said, and was possibly excreting DOC. Just a guess.

Ok, but also plausible is that heterotrophic bacteria were unable to grow and use the organics available because of a shortage of N. Coincidence is also very plausible. Lack of detectable nitrate with the HR doesn’t say much since 0 ppm reading is within spec for a real 2 ppm.

I’m not convinced the data exists to say what organic levels are desirable
Vs undesirable, not least of which is because it lumps all types of organics together, whether they are toxins or foods or whatever.

 

[Dburr1014]

What strain of dinoflagellates are in corals? Is it the same we see blooms of in the water column and on the sand?

I don't want to speak for him but I think he meant to say dinoflagellates is a zooxanthellae.

 

[CHSUB]

I don't want to speak for him but I think he meant to say dinoflagellates is a zooxanthellae.

It was an attempt at irony, I guess failed…haha. Zooxanthellae is a dinoflagellate and some blame dino blooms on low inorganic nutrients however some also blame starving corals on the same low inorganic nutrients that causes dinos to bloom: both Dinos one blooms one starves!

 

[BeanAnimal]

blame dino blooms on low inorganic nutrients however some also blame starving corals on the same low inorganic nutrients that causes dinos to bloom: both Dinos one blooms one starves!

There is nothing contradictory there. Low nutrients can starve the dinoflagellates living in coral while allowing unwanted dinoflagellates in the sandbed to thrive.

It’s like a drought that kills crops but lets weeds take over. Both are plants with chlorophyll. The same lack of water harms one while favoring the other. Once the weeds take over, adding water back does not reverse the condition, it actually makes it worse by allowing the weeds to grow even faster.

 

[Miami Reef]

There is nothing contradictory there. Low nutrients can starve the dinoflagellates living in coral while allowing unwanted dinoflagellates in the sandbed to thrive.

It’s like a drought that kills crops but lets weeds take over. Both are plants with chlorophyll. The same lack of water harms one while favoring the other. Once the weeds take over, adding water back does not reverse the condition, it actually makes it worse by allowing the weeds to grow even faster.

Nice analogy.

 

[Miami Reef]

Edit

 

[Hans-Werner]

Can't corals limit zooxanthellae growth themselves? We know that corals can "cleaning house" when the temperature gets too high, what we call "coral bleaching".

So why should a coral in a reef tank starve when it only needs to throw out (some of) its zooxanthellae?

Yes, maybe under certain circumstances corals can limit zooxanthellae growth themselves by actively limiting nutrient supply to zooxanthellae.

When corals throw out zooxanthellae, this worsens starvation of corals because the zooxanthellae are the ones supplying corals with energy and organic carbon compounds for growth.

 

[rishma]

My experiment (using that term loosely) has begun. My tank is at 0.0 nitrate based on two tests (Hanna HR and Red Sea Pro). I think it’s been there about one week. I’ve been dosing a small amount of ammonia daily for 6 weeks. I’m going to increase that dose until a see a fairly steady but low nitrate level. I ordered some urea and will mix that into the ammonia solution when it arrives.

Corals look fantastic at the moment, though I admit to being a bit nervous about my 0 nitrate. We shall see…

 

[Randy Holmes-Farley Verified Community Expert]

My experiment (using that term loosely) has begun. My tank is at 0.0 nitrate based on two tests (Hanna HR and Red Sea Pro). I think it’s been there about one week. I’ve been dosing a small amount of ammonia daily for 6 weeks. I’m going to increase that dose until a see a fairly steady but low nitrate level. I ordered some urea and will mix that into the ammonia solution when it arrives.

Corals look fantastic at the moment, though I admit to being a bit nervous about my 0 nitrate. We shall see…

Sounds like a nice experiment. :)

 

[Hans-Werner]

It was an attempt at irony, I guess failed…haha. Zooxanthellae is a dinoflagellate and some blame dino blooms on low inorganic nutrients however some also blame starving corals on the same low inorganic nutrients that causes dinos to bloom: both Dinos one blooms one starves!

Simply summing up "inorganic nutrients" is not helpful. This is something I try to tell for years. There are fundamental differences in the different nutrient limitations.

The mechanisms are complex. There is also the coral host and for scleractinians the calcification process that consumes and demands phosphate. If the corals are doing bad because there is a lack of phosphate this could limit corals ability to limit zooxanthellae inside and also to compete with dinoflagellates outside.

There are several articles confirming that dinoflagellates have ecologic advantages at phosphate limitation, i. e. by producing more toxins, inhibiting growth of competitors.

 

[Hans-Werner]

Since we are back on urea, I have an important point that is also stressed by the article I have linked:

Urea can only be used by corals when they have enough nickel for full urease activation. Maybe 20 years ago users told that when dosing our K+ and A- Elements their corals where getting darker. This could be because of some iron supply. However, I think it was the nickel supply that increased the access of corals to urea-N.

I noticed that the darkening may be temporary.

This would mean, there most likely was some buildup of urea in the tank which was used by the corals after enough nickel was available for better urease acitivity. After the buildiup was processed a new steady state of urea and N established and the corals regained their normal or better coloration.

This means, nickel maybe can supply more urea-N to the coral than more urea can, just by better access.

 

[Randy Holmes-Farley Verified Community Expert]

This means, nickel maybe can supply more urea-N to the coral than more urea can, just by better access.

Interesting. Thanks for that info. :)

 

[Hans-Werner]

Can the Zooxanthellae inside the coral also excrete organic carbon to the water column?

If this would be the case, it would take the way through the coral and the coral's metabolism I think. A lot of the organic carbon the zooxanthellae supply to the coral is excreted with coral slime, if I recall this correctly.