Dinoflagellate die off - resulting alkalinity increase

[Koleswrath]

Howdy folks, I'm trying to understand a recent rise in alkalinity in my tank after getting Dinoflagellates under control. I don't think anything changed in my husbandry day to day from before the spike to after so it's a bit of a mystery. It wasn't that big of a swing - 8.4 dKH to 9.4 over a couple days between alk tests but still significant.

• I dose Kalk via gravity drip valve which needs adjusting here and there but doesn't vary wildly. Alk has been very stable prior to this.
• I noticed the rise soon after really getting Dino's under control.
• I wasn't doing many water changes due to the Dino's. 
• PH is still pretty steady at 8.1-8.2

 

Nothing was really affected but my Seriatopora doesn't seem to have the continuously great polyp extension it did before the alk jumped. Monti and Slimer still rocking.

 

Could this have been from the rotting of the dead Dinoflagellates in the sand/rocks causing a localized lowering of PH and dissolution of my sand and rock? Would it be that noticeable? Water volume is only 7 gallons.

The only other idea I have is that some Kalk built up in my tubing and was all of a sudden dislodged. I think I would have noticed a PH spike if this happened though.

 

Any other possibilities? 

[mcarroll]

2 hours ago, Koleswrath said:

Howdy folks, I'm trying to understand a recent rise in alkalinity in my tank after getting Dinoflagellates under control.

Did you raise NO3 (and probably PO4) as part of your getting them under control?

 

NO3 -> NO2 (denitrification) makes alkalinity.

 

2 hours ago, Koleswrath said:

Could this have been from the rotting of the dead Dinoflagellates in the sand/rocks

Unlikely – the first noticeable effect from this is the tank's dissolved nutrient levels (N & P) dropping to below-testable levels.  If that's not happening, then you don't have rotting dino's. 😉 

 

There's a paper on that in my dino thread BTW....what it takes, nutrient-wise, to decompose dino's.  If you're into gardening, dino skeletons, aka "theca", are a 1000:1 carbon source.  It takes A LOT of nutrients to decompose them.

 

I'm guessing it was just the NO3 added to aid in said decomposition (but I can't remember your dino situation and all you did/didn't do.)

[Koleswrath]

13 minutes ago, mcarroll said:

Did you raise NO3 (and probably PO4) as part of your getting them under control?

 

NO3 -> NO2 (denitrification) makes alkalinity.

Yep, I was NO3 dosing to keep a 5-10ppm level.

 

NO3 -> N2 (do you mean?) definitely produces alk but I don't see a lot of that taking place in my tank. No deep sand bed and I don't think the hobby generally accepts denitrification taking place in significant amounts in live rock anymore. 

 

NO3 uptake by algae (which I assume is where a good amount of my NO3 is going) also produces bicarbonate - but according to RHF I'd need ~20ppm of N03 consumed to raise alk 1dKH. I was dosing 3ppm per day so I guess if test kit inaccuracy is taken into account that could have been it. I'm not keeping accurate records of dosing N03 and P04 but it's very possible that soon after my alk raised I stopped needing to dose N03 to maintain levels (because the dinos weren't blooming anymore) which explains why my alk isn't still noticeably rising. 

 

I was hoping for a cooler and more interesting solve to this mystery. Thanks though....

😞

 

[mcarroll]

17 hours ago, Koleswrath said:

NO3 -> N2 (do you mean?)

Yes. 😉 

 

17 hours ago, Koleswrath said:

but I don't see a lot of that taking place in my tank. No deep sand bed and I don't think the hobby generally accepts denitrification taking place in significant amounts in live rock anymore. 

That's pre-liverock lore from back when denitrification was thought to require a box under your substrate that was regularly doped with ethanol.   (aka Carbon dosing.  I think someone is still making those boxes, BTW.)

 

In a non-reef tank, that info is mostly true.  Without live rock (ie aragonite rock and/or sand), there's no appropriate space for denitrification like there is in a typical saltwater reef tank that's based on live rock.

 

(Siporax, Matrix and all similarly porous bio-media are made to support denitrification in these "unfriendly" habitats.)

 

18 hours ago, Koleswrath said:

NO3 uptake by algae (which I assume is where a good amount of my NO3 is going) also produces bicarbonate

I can't discount this off the top of my head, but algae are likely to take up ammonia sources, even at low levels, before oxidized forms of N like nitrate.   It takes a lot more energy to utilize nitrate compared with ammonia. 

 

(BTW, do you have the link to the RHF article you're referring to about algae and alkalinity?)

 

18 hours ago, Koleswrath said:

I'm not keeping accurate records of dosing N03 and P04 but it's very possible that soon after my alk raised I stopped needing to dose N03 to maintain levels (because the dinos weren't blooming anymore) which explains why my alk isn't still noticeably rising. 

Very possible!  👍

 

18 hours ago, Koleswrath said:

I was hoping for a cooler and more interesting solve to this mystery. Thanks though....

😞

Sorry to disappoint!!

 

(I think all of this stuff is pretty cool and interesting!! 😄 )

[Koleswrath]

16 minutes ago, mcarroll said:

That's pre-liverock lore from back when denitrification was thought to require a box under your substrate that was regularly doped with ethanol.   (aka Carbon dosing.  I think someone is still making those boxes, BTW.)

Yep, they’re reinventing the wheel for a new generation of reefers. Just with methanol now and expanded PVC instead of acrylic.

So to be clear - is your stance that denitrification IS happening in liverock to a measurable degree?

 

18 minutes ago, mcarroll said:

(BTW, do you have the link to the RHF article you're referring to about algae and alkalinity?)

http://reefkeeping.com/issues/2004-12/rhf/index.htm
 

[mcarroll]

1 hour ago, Koleswrath said:

Yep, they’re reinventing the wheel for a new generation of reefers. Just with methanol now and expanded PVC instead of acrylic.

It may have been methanol before as well....it was never popular and I never tried it.   It was just a persistent presence in magazine ads from the 1970's onward. 😉 

 

Spotte mentions it in his "Captive Fishes.." book....it's a problematic design....hard to maintain, leaky.

 

1 hour ago, Koleswrath said:

So to be clear - is your stance that denitrification IS happening in liverock to a measurable degree?

I haven't independently verified it in my own tank or anything, but you can't stop it from happening to the full extent possible (theoretically it should be a carbon-limited process).  

 

The processes in live rock (and sand) are more complex than denitrification filters though...and so are more capable.  

 

Also, the less "clean" a tank is, the better it should be able to denitrify....detrius is a significant (the best, actually) carbon source for denitrification.  (This has actually been proven experimentally – aquaculture folks care about this too.)

 

1 hour ago, Koleswrath said:

http://reefkeeping.com/issues/2004-12/rhf/index.htm
 

Thanks!  

 

The only thing I see specifically about algae is the Figure that shows coralline algae and talks about alkalinity consumption.

 

I don't see where algae growth (NO3-uptake) contributes to increasing alkalinity though.  Am I just scanning it too fast?  (Can you quote for me?)

[Koleswrath]

7 minutes ago, mcarroll said:

I don't see where algae growth (NO3-uptake) contributes to increasing alkalinity though.  Am I just scanning it too fast?  (Can you quote for me?)

Likewise, equation 3 (below) shows the uptake of nitrate and CO2 into macroalgae to form typical organic molecules:

(3)  122 CO₂ + 122 H₂O + 16 NO₃^-    à  C₁₀₆H₂₆₀O₁₀₆N₁₆  + 138 O₂  +  16 HCO₃^-

Again, one bicarbonate ion is produced for each nitrate ion consumed.

[mcarroll]

54 minutes ago, Koleswrath said:

Likewise, equation 3 (below) shows the uptake of nitrate and CO2 into macroalgae to form typical organic molecules:

(3)  122 CO₂ + 122 H₂O + 16 NO₃^-    à  C₁₀₆H₂₆₀O₁₀₆N₁₆  + 138 O₂  +  16 HCO₃^-

Again, one bicarbonate ion is produced for each nitrate ion consumed.

 

Thanks again!    So it's the same kind of equation as with bacterial consumption/denitrification.  

 

The only "rub" on this vs bacterial denitrification is that plants don't prefer N03 when other (more chemically available) sources are present.  And there are always other sources, such as ammonia and urea.  

 

I can imagine the possibility of a large standing crop of algae in a small fish tank using up all available N sources though, so it's still possible that this kind of alkalinity production could be detectable.

 

One other thing the RHF article (and you) said though, is that changes of this nature are probably only detectable in the long term....the amounts of alkalinity produced are miniscule.  At least ordinarily.

 

Interestingly, water changes due to high NO3 can deplete alkalinity....very counterintuitive, at least at first glance.

 

Anyway, after re-reading your original post...

 

I don't know if any of this can explain a +1 dKH shift over the course of just a couple of days.  I think that's too short a time frame, unless you had a MASSIVE crop of green algae (or similar) at the time.  Seems like a crop that big would have become its own problem rather than being a sign the tank was back in balance like it usually is post-dino's, so doesn't seem likely.  Any chance you can ascribe any of that variance to testing error?  Probably not....but if we imagine it, that could explain enough of the +1 dKH to possible leave the remainder to be explained by the more interesting part of the discussion.  Just some thoughts. 

[Koleswrath]

36 minutes ago, mcarroll said:

  Any chance you can ascribe any of that variance to testing error?  Probably not....but if we imagine it, that could explain enough of the +1 dKH to possible leave the remainder to be explained by the more interesting part of the discussion.  Just some thoughts. 

Ya, I was thinking margin of error on the Hanna Alk checker as well. I don’t think testing error factors in since we’re talking multiple tests over multiple days all fairly consistent. That Hanna Alk checker is pretty rock solid too.

Ah well, like most reef mysteries it’s probably a combination of all these factors plus a few we don’t know about.

c’est la vie

[PJPS]

On 3/16/2023 at 2:38 PM, Koleswrath said:

Howdy folks, I'm trying to understand a recent rise in alkalinity in my tank after getting Dinoflagellates under control. I don't think anything changed in my husbandry day to day from before the spike to after so it's a bit of a mystery. It wasn't that big of a swing - 8.4 dKH to 9.4 over a couple days between alk tests but still significant.

• I dose Kalk via gravity drip valve which needs adjusting here and there but doesn't vary wildly. Alk has been very stable prior to this.
• I noticed the rise soon after really getting Dino's under control.
• I wasn't doing many water changes due to the Dino's. 
• PH is still pretty steady at 8.1-8.2

 

Nothing was really affected but my Seriatopora doesn't seem to have the continuously great polyp extension it did before the alk jumped. Monti and Slimer still rocking.

 

Could this have been from the rotting of the dead Dinoflagellates in the sand/rocks causing a localized lowering of PH and dissolution of my sand and rock? Would it be that noticeable? Water volume is only 7 gallons.

The only other idea I have is that some Kalk built up in my tubing and was all of a sudden dislodged. I think I would have noticed a PH spike if this happened though.

 

Any other possibilities? 

The dinos may have halted/slowed consumption.  Stop dosing until consumption is back to normal would be what I do.

[Koleswrath]

12 minutes ago, PJPS said:

The dinos may have halted/slowed consumption.  Stop dosing until consumption is back to normal would be what I do.

Yes, this crossed my mind as a possibility as well. I'd bet they slowed down for sure but I'm certain they still grew a bit through the few weeks of Dino's. Especially the Digi. I've since mixed about 1/3 of the amount of Kalk powder in my drip bin and Alk has been slowly coming down. 

 

[PJPS]

11 minutes ago, Koleswrath said:

Yes, this crossed my mind as a possibility as well. I'd bet they slowed down for sure but I'm certain they still grew a bit through the few weeks of Dino's. Especially the Digi. I've since mixed about 1/3 of the amount of Kalk powder in my drip bin and Alk has been slowly coming down. 

 

My thinking is as follows - everything mentioned could be happening, I figure there's 2 things you can do - water changes and adding less alk to the system.  The rest is interesting, but doesn't fix the immediate problem of rising alk 🙂

[Koleswrath]

Oh this is definitely just an interesting  curiousity post. Bored at work.

Alk’s been stable since the die off and is well under control. 😁

[P. mandevillei]

I think I might be able to add a new perspective to this increase.

On 3/18/2023 at 4:09 AM, PJPS said:

The dinos may have halted/slowed consumption.  Stop dosing until consumption is back to normal would be what I do.

I agree with this. Instead of generation of new bicarbonate (since, as far as I can see it, most of the bicarbonate comes from dosing, not biological processes), I think you should pay more attention to its consumption. Micro algae can directly use bicarbonate as carbon sources, which takes the role of CO2 in photosynthesis. It is possible that blooming Dino’s used to take in a great amount of bicarbonate, and when it subsided, the absorption rate of bicarbonate slowed down faster than your dosage reduction, thus resulting in elevated alkalinity.

[mcarroll]

5 hours ago, P. mandevillei said:

I think I might be able to add a new perspective to this increase.

I agree with this. Instead of generation of new bicarbonate (since, as far as I can see it, most of the bicarbonate comes from dosing, not biological processes), I think you should pay more attention to its consumption. Micro algae can directly use bicarbonate as carbon sources, which takes the role of CO2 in photosynthesis. It is possible that blooming Dino’s used to take in a great amount of bicarbonate, and when it subsided, the absorption rate of bicarbonate slowed down faster than your dosage reduction, thus resulting in elevated alkalinity.

Interesting theory, but I wonder about the quantities and whether it would be enough to be detectable....especially in this case where dino's were detected mostly via microscope, and they were never dominant in the tank (that I saw)....there was always green algae and cyano in the same microscope frame with the dino's.

 

What was apparent at least in pictures was a LOT of cyano.  Maybe same equation with bicarb. consumption....but I still wonder if it could be enough to be detectable.   You know any sources which quantify this?  I've only seeing folks referring to the process so far....no specifics.

[P. mandevillei]

On 4/10/2023 at 12:13 AM, mcarroll said:

Interesting theory, but I wonder about the quantities and whether it would be enough to be detectable....especially in this case where dino's were detected mostly via microscope, and they were never dominant in the tank (that I saw)....there was always green algae and cyano in the same microscope frame with the dino's.

 

What was apparent at least in pictures was a LOT of cyano.  Maybe same equation with bicarb. consumption....but I still wonder if it could be enough to be detectable.   You know any sources which quantify this?  I've only seeing folks referring to the process so far....no specifics.

Well I’ve also only read about the process itself. I did a quick search and didn’t find anything useful (that’s available for free at least lol) that clarifies the specific consumption ratio of CO2 and HCO3- when they’re both present in abundance. What I do know for sure is that cyano can also utilize bicarbonate directly. In fact there’s research that proposes using sodium bicarbonate as main carbon source for cyano cultivation. See Bicarbonate produced from carbon capture for algae culture and The use of bicarbonate for microalgae cultivation and its carbon footprint analysis

[mcarroll]

Interesting.   From searching and reading some more (still no specifics!!!) it sounds like bicarb-usage must only happen at an appreciable rate under CO2-limitation....which is usually only "normal" inside a large established colony (or mat) of algae where demand concentration is high and flow is low, or under experimental/lab conditions.

 

[Koleswrath]

Definitely. Depending on what we consider a large mat this could have contributed as well. I assume that even a few layers of bacteria could be C02 limiting to the bacteria underneath.

 

[mcarroll]

18 minutes ago, Koleswrath said:

Definitely. Depending on what we consider a large mat this could have contributed as well. I assume that even a few layers of bacteria could be C02 limiting to the bacteria underneath.

 

I'm sure it did contribute to some degree.  But with the amount of cyano pictured, there are no dense, established mats....not between the effects of tank flow and the OP's cleaning activities.   I suspect there would only be minimal (probably undetectable on a hobby kit) bicarb usage in this scenario.

 

Check out the Wikipedia on microbial mats to get the idea of what an established mat is and why this ability with bicarb exists.   This lifestyle explains a lot about why cyano and other related microbes are such chemistry powerhouses to begin with.

 

I've had thick (1+ cm) cyano mats before....they're usually layered and packed with detritus just as described in the W article.  Tank-wide cyano blooms don't often produce established mats.  Mine actually came with my live rock....don't even think it was the same type of cyano as the red stuff that blooms in new tanks like this.

[P. mandevillei]

21 hours ago, mcarroll said:

Interesting.   From searching and reading some more (still no specifics!!!) it sounds like bicarb-usage must only happen at an appreciable rate under CO2-limitation....which is usually only "normal" inside a large established colony (or mat) of algae where demand concentration is high and flow is low, or under experimental/lab conditions.

 

Problem Dinoflagellates and pH Here it says “Two marine dinoflagellates, Amphidinium carterae Hulburt and Heterocapsa oceanica Stein, demonstrate active uptake of carbon dioxide (or carbonic acid), but not bicarbonate… On the other hand, three marine bloom-forming (red tide) dinoflagellates, Prorocentrum minimum, Heterocapsa triquetra and Ceratium lineatum, have been shown to take up bicarbonate directly, with bicarbonate accounting for approximately 80% of the carbon dioxide they use in photosynthesis.” So when pH is high, CO2 goes scarce in water, and some dino’s will compensate for it with bicarbonate considerably. But I looked up the original paper, and in it high pH was defined as 8.5 or 9.1, while 8.0 was considered low. So I guess you’re right. Bicarbonate absorption rate may not be so high in our tanks. I don’t know which process is dominant, absorption for photosynthesis or production by nitrate utilization.

 

On 3/18/2023 at 2:18 AM, Koleswrath said:

122 CO₂ + 122 H₂O + 16 NO₃^-    à  C₁₀₆H₂₆₀O₁₀₆N₁₆  + 138 O₂  +  16 HCO₃^-

BTW, judging from that nitrate assimilation equation posted (it isn’t balanced in fact; it should be 138 H2O), this process is dependent on photosynthesis. Under stress of CO2, this process might be possible with HCO3- as reactant and produce carbonate. Just a guess. This stuff really gets confusing! Makes my head ache.

[mcarroll]

On 4/14/2023 at 10:27 AM, P. mandevillei said:

Problem Dinoflagellates and pH 

That is a classic.  The base chemistry is solid as usual.  But I love how you can obviously tell from the topical content (ie dino's) how rare dino's actually were back in 2006.

 

For example, they couldn't even score photos of actual dinoflagellate blooms for the article.  The photos presented are of algae that clearly aren't dino's with captions one after another like "An infestation in the aquarium of [some internet person] that may be dinoflagellates."  (<---Only edited to protect the innocent....otherwise that's a direct quote from one of the captions.). Seems probable that nobody involved really had any idea.

 

In fairness, green dino's (featured in the article) apparently do exist....just not as blooms in any of our tanks.  As it turns out (no surprise to anyone reading now), we get dino-colored dino's.  (peridinin, dinoxanthin, and diadinoxanthin). 😉 

 

BTW, I wonder if pH was all he asked about in his survey???  If there was more data, it might be interesting to look at in a modern light.  

 

🤷‍♂️