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Featured Carbon source for macroalgae photosynthesis?

Discussion in 'Chemistry' started by GlassWalker, Apr 13, 2015.

  1. GlassWalker

    GlassWalker Registered

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    I might be over-thinking again... in my 2nd tank I'm dosing Balling classic. Calibration issues with the doser aside (Ca crept up to 5% overdosing relative to other channels), I think my KH consumption is faster than balance. I know this is not an unusual scenario for classic/Triton in itself.

    I'm wondering if this is not a case of the corals taking significantly unbalanced consumption, but could macroalgae be the culprit here? My reasoning is based on recently reading up on carbon intake by freshwater aquatic plants. They prefer CO2 as their primary carbon source, but some plants have adapted to also take bicarbonate in some form to supplement it. In seawater, we have a pretty much guaranteed supply of bicarbonate so it would seem logical if marine plants have evolved to make use of such alongside available CO2.

    I've been having minor algae problems in the DT, and to try and fix that, I significantly increased the sump light cycle to 22h on, 2h off. This is working and most of the unwanted algae has died off in the DT. I didn't make note of when I did this, but I think it roughly coincides with a drop in measured KH starting around a month ago. The off period was introduced since I read that having a light cycle produced more growth than continuous lighting. I haven't seen any research into at what might be the optimal photoperiod. Where is the point where more light duration becomes counter-productive? Anyway, the sump contains mainly chaeto, but recently I also introduced some caulerpa racemosa. Also I've inadvertently created an algae scrubber which decided to form on one of the sump partitions.

    Anyway, given the growth of the sump algaes, I have to wonder if they might be enough to take a significant amount of bicarbonates out of the system.

    If no one has done so before, I'm debating doing a test myself. The next time I harvest chaeto, I could place it in a spare small tank next to a south facing window. I could dose the water with fertiliser so growth isn't limited by nutrient availability. Then I can simply measure the KH at the start, and see if it drops over time. I would hope over a sufficiently short period in a new tank setup, there wouldn't be appreciable coralline formation or other calcium carbonate depositors to confuse the results.
     
    Last edited: Apr 13, 2015
  2. Eyore

    Eyore Guest

    Tbh i dont know, biology is behind chemistry in my interests. For complex biology i normally ask dami, perhaps clearwater or trout may know more

    Fwiw i do not believe corals take an unbalanced amount, calcium carbonate is just that, some of the molecules maybe strontium or other cations, but it cannot take an unbalanced amount of the anion (bicarbonate) in relation to its cations (vast majourity being calcium)
    Its the tank that is using extra bicarbonate.
     
  3. Clearwater

    Clearwater Registered

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    I am not aware of significant take up of carbonates in Macro Algae save the hard slow growing stoney sp

    corals will deposit skeleton in a balanced way, high phosphates may inhibit strontium take up and the skeletons are less strong, be we are not looking at this aspect

    When nutrients rise the Bacteria in the nitrogen cycle do consume extra carbonates as part of the process esp. in the anaerobic final stage, this also depresses Ph values as nitric acid compounds are also produced
    esp in DSB or MM systems which I did a lot of reading into as I couldn't work out why the dKH was depleted so fast

    I suspect the Bacteria are primarily processing the Nitrogen Cycle and the Macro Algae mopping up the Phosphates, hence the extra Carbonate take up

    I wouldn't worry about it, all tanks are different we have after all an artificial environment
     
  4. GlassWalker

    GlassWalker Registered

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    Thanks for the clarification on coral usage, at least that applies to the deposition. Could there be other processes which may lead to unbalanced consumption? Or do we take that as insignificant?

    I had forgotten about the carbonate usage in nitrifying bacteria, but I don't believe I'm feeding the tank significantly differently during the period of observed change. I wasn't aware that the denitrifying bacteria also did, if I am reading that correctly. I do think the only significant change recently was the increase in photoperiod over the algae bed in sump.

    From my perspective I guess I posed this question as I noticed a change, and I'm curious where this change is coming from. I recalibrated my doser last night so I intend to reset that and do a one-time correction to KH, and see if the pattern continues.

    I might also try the cheato experiment described previously, even a non-result would be as useful as a positive one to know either way.
     
  5. Clearwater

    Clearwater Registered

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    Think the Cheato Experiment is worth doing

    as tanks mature the consumption will need to be adjusted for, have you considered reduced nutrients = faster coral growth, this also has a part to play
     
  6. trout

    trout Registered

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    Some macro algae do deposit calcium and sodium in their body in significant amounts. Caulerpa is an example. Refer to Ron Shimek's article for more information. Another example is Halimeda sp. "The algal body [of Halimeda] is composed of calcified green segments. Calcium carbonate is deposited in its tissues, making it inedible to most herbivores. " (Sourec Wikipedia).

    I will also look for references for the body composition of chaeto and will report back in due course if I find any information.
     
  7. jim_fitz

    jim_fitz Admin Staff Member

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    and dont forget as your corals grow
    there is more of them to grow

    if that makes sense
    i use balling light and there is no balance between dosing rates
    i just test regularly and adjust if necessary
    i also carbon dose using pellets and im now convinced of reduced growth when i top up the pellets
    so then i test more regularly to reduce dosage
     
  8. GlassWalker

    GlassWalker Registered

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    trout, thanks for the link, I'll have to go through that in more detail later.

    To clarify, I'm not concerned with calcium carbonate deposition at all. My original question is if there was a significant carbonate (without calcium) consumption mechanism due to photosynthesis. I think there is some, where it may be used as an alternative to CO2 as a carbon source, but the question is of significance.

    Thinking more to my proposed experiment, maybe I should do a few variations in parallel?
    1, "normal" sea water, with algae
    2, "normal" sea water, without algae as a control
    3, zero KH sea water, with algae. No idea how I'm going to make that...
     
  9. Eyore

    Eyore Guest

    The clue maybe in your op

    Without knowing the exsact levels over an extended period, snd exsactly when bicarbonate use increased, it is hard to have an educated guess.

    But calcium and bicarbonate is supersatured beyond what water can contain due to the presence of magnesium.
    An increase in salinity and or calcium (but particularly calcium), will start to kick bicarbonate out, leading to biased dosing
    The correct ratio to form caco3 and leave over 1 mol of sodium and chloride is 84g/l nahco3 and 73.5g/l cacl22h2o (8g to 7g)
     
  10. Clearwater

    Clearwater Registered

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    I think this is being over thought

    For 7 year I have run with a huge refugium
    Lit 25/7 as my only export mechanism
    Even going months without water change

    The elements came from a Ca reactor and are there fore balanced

    The only need for carbonate dose was to buffer Ph this I did with Carbonate of Soda
     
  11. Eaval

    Eaval Registered

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    How do you light it for 25 hours a day? :p
     
  12. Eyore

    Eyore Guest

    The calcium and bicarbonate is balanced out of the reactor, but if you add sodium carbonate for ph, bicarbonate and calcium addition are no longer in balance, and you have an excess of sodium
    (If you see my point)

    I do agree - overthinking, however i like the desire to learn and think
     
  13. Clearwater

    Clearwater Registered

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    Fat fingers LOL
     
  14. Clearwater

    Clearwater Registered

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    Didn't see it as an issue it was only 2 or 3 times a year

    If done all the time it would create an imbalance

    That said damm near every ICP test I see is unbalanced
     
  15. GlassWalker

    GlassWalker Registered

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    Been doing some more thinking on the experiment...

    To produce a zero KH water, I can easily make up the bigger constituents with what I have at home: NaCl 27g, MgCl2 2.4g, CaCl2 1.1g, MgSO4 3.4g, (NaHCO3 0.2g), KCl 0.76g. Figures are rounded and I might tweak them some more later, to be mixed to make 1L for approx 35ppt. Assumes anhydrous and I will scale it for hydrates as needed later. Minor/trace elements are going to be challenging. I'm not proposing to go into the synthetic salt water business myself, but making a one off small quantity for this test shouldn't be too demanding. I will also include nitrate and phosphates for the algae to feed off.

    Assuming trace could be overcome using off the shelf supplements (I have several already) then I would initially make up a batch of zero KH seawater. A portion of that will be saved. To the rest, I then add in the KH to typical levels.

    I will then harvest some algae from one of my sumps. That will be split into roughly equal portions for each water type. I will shake off as much of the water as is practical and weight them. Then I'll place them into the water types, and the last step I haven't decided on yet. I'm debating using artificial lighting, or sunlight. In either case, I will try to ensure the lighting is even and doesn't vary between them.

    On each sample I will mark the initial water level so I can top off for evaporation. I can measure KH up to daily and see if anything is happening. I think I might also top off the water with zero KH mix to replace water used in testing, so as to maintain salinity without adding KH. This might not be significant normally but I wont have much starting volume, and testing over many days can be a significant percentage of that.

    If I can find suitable containers, I'll implement this on the weekend.
     
  16. Eyore

    Eyore Guest

    I can see you payed attention lol
    I havent checked your figures, but they look roughly correct to me
    You need to adjust your numbers slightly from mg/l to suit mg/kg (increase 2.5%)

    I like that you have taken the time to figure that out, though i arent sure of your experiment, but hell, why not

    You will tow to get hold of the trace elements you need, from experience, unless you know the right people, but some stuff is pretty easy to get, you just have to figure out how you want to apply the elements
     
  17. GlassWalker

    GlassWalker Registered

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    My thought was to top up to 1L after assembling the salts, thus there must be xx g/l. Never did figure out if you can work out the volume of solid after dissolving in liquid.

    The salt balance was kinda easy to do in a spreadsheet, at least for the bits considered so far. I'm a bit surprised that magnesium sulphate came out so high relative to the chloride, but that's the only way I could get sulphur levels up. Unless it is provided in some other form than sulphate in NSW that is.

    The trace I'm thinking I might be able to get away with general trace additives. Most of them aren't exactly open with what's in them, but since I'm only trying to grow algae and not some sensitive coral, I hope to get away with it. I'm reverting back a little to freshwater planted tank theory here, where basically as long as you're not running out and limited on anything, plants can grow as fast as they can. My other option is to forget about the zero KH part of the test and use regular salt. I can then only try some permutations with varying levels of natural to increased KH instead. Thinking more, there's a possible option 3, which is to dump so much calcium into the salt mix I precipitate out the alk... but that would probably mess things up in other ways.

    My biggest concerns about this is I can't really afford to run multiple samples as a proper scientist might, to get some average. Unless it is a big effect present, errors and minor differences might outweigh it. Then again, if it isn't significant, that's useful to know too...

    Will have another think about it in the morning before I do anything, might change my mind again by then!
     
  18. Eyore

    Eyore Guest

    If you want theoretically everything, but in practice most-

    I would suggest 58.44g nacl to 25 g tropic marin pro mineral, and then recalulate to 36000 ppm
    I say 36000 ppm as this is mg/l, and a litre of seawater weighs more than 1 kilo. The values for seawater you should be working to are in mg/kg

    It would be interesting to see what this tested at, but its the cost effective way

    Doing it individually would cost you seroius money- things like fm trace b do not contain everything (not aware of lithium for eg) and strontium iodine possibly fluoride will be dosed above an amount to balance, so you have no chance of using in any meaningful way

    Your other way is to calculate everything out, and buy a compound for every element, and this will cost you (a) financially a lot (4 figures) (b) do your head in as most places wont deal with you without a business adress and proven approved use (c) it will take a lot of time to figure what compounds to use (not a few days)

    If you go this way, i would get some strontium chloride, use a standard iodine solution, and some boric acid or borax, and then stop there as its too much hassle

    Hth
     
  19. GlassWalker

    GlassWalker Registered

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    I definitely agree that buying individual trace is not practical on multiple levels, but you have reminded me I already have an all in one mix on hand already: I use Tropic Marin Balling classic. In previous discussion with Balling, when using the TM salts, the part C balances the "left over" sodium chloride to be equivalent to that of their Pro Reef salt. So I have all the trace in the right balance in one handy powder already :) I don't need to worry about other trace additives which makes things a lot simpler. Just need to work backwards form Classic & TMPR to determine what must be in part C, and re-add NaCl+A+B+possibly magnesium source in the correct ratios.

    Also thanks for pointing out (again) that salinity is measured mass/mass not mass/volume. I overlooked this and assumed the wrong one, but it looks easy to compensate. It is easier for me to measure mass accurately than volume.
     
  20. Eyore

    Eyore Guest

    No worries, you kind of answered the question already as to what is in nacl free

    Assuming you can, i would be interested to know the levels you test for ca mg kh i on your "salt mix"
    There will be some conflict and preciptation, i cannot see calcium being correct for one, but you should be able to manually compensate with balling chemicals. Sulphate loss is also a given, but this would take some thinking around this problem (i believe i will be able to tell from tested levels how much is likely precipitated)

    Post your figures for nacl and tmpm when you worked them out, i dont know them off the top of my head, but i do know how to quickly work out

    But i am sure you are already on with this and will have them already, half the fun is in the calculating lol
     
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