Why no K2SO4 & K2CO3?

Discussion in 'Aquarium Fert Dosing' started by Cro, 8 Sep 2009.

  1. Cro

    Cro Member

    Messages:
    103
    Just wondering why when I read up on EI the dosing always says to add;

    KN03
    KH2PO4
    MGS04
    Trace elements

    But never lists K2SO4 & K2CO3?
     
  2. JamesC

    JamesC Member

    Messages:
    1,276
    Location:
    Bexley, Kent
    People add K2SO4 as a source of potassium but if you dose EI then you get more than enough from just the KNO3 alone so there's no need to add any more. Same goes for the K2CO3 if you are adding it for the potassium. If you are adding it for the CO3 then this will raise KH which isn't really needed with the dosing. Some people do add some K2CO3 or NaHCO3 when doing water changes to add some alkalinity if their water is very soft.

    ADA's Brighty K is K2CO3 or KHCO3 which acts as a potassium source and also adds a bit of buffering to counter act the effects of ADA Aqua Soil which strips out KH.

    James
     
  3. Cro

    Cro Member

    Messages:
    103
    Thant makes sense. :thumbup: As I have very hard water in my area I will continue as normal.
     
  4. keymaker

    keymaker Member

    Messages:
    255
    Location:
    Budapest, Hungary
    It obviously depends on the K amount of the tap water, but my experience tells me that you can simply not add enough K with KNO3 to get the coreesponding EI levels of K and NO3 in the tank. Most of the times you need to add K2SO4 - here in Hungary anyway - to compensate for the lower molar weight of K in the equation.

    Adding more KNO3 would be one solution but in time it can result in excess levels of NO3 which to a certain point (untill say 50-60ppm) is OK for most (not all) fish and inverts, but why bother if one can get it right...

    Say you have 0ppm K in your tap water. Add 80 grams of KNO3 to 1 liter DI water and dose daily 1ml/20l with 50% weekly water changes. You will get 19-34 ppm NO3 in your tank water and 13-23ppm K. It is therefore desirable to add 36 grams of K2SO4 to the solution to obtain 20-34ppm K in the water - to have something I call "PPM balance" in your dosing. I'm not saying this is absolutely needed, just recommend it to be on the safe side from the K deficiency signs on the plants. ;)
     
  5. JamesC

    JamesC Member

    Messages:
    1,276
    Location:
    Bexley, Kent
    That is very true indeed and is a good recommendation to add some potassium sulphate if you know or suspect that you source water is low on K.

    Thanks for pointing out.
    James
     
  6. Cro

    Cro Member

    Messages:
    103
    I think I have a K deficiency and I know that I don't want to add any more N03 (have enough fish to do that for me) So how much K2S04 should I add to my EI dose when I'm currently dosing 6tsp of KN03 & 6tsp of KH2PO4 to 600ml water adding 50ml 3 times per week?

    Cheers

    Alex
     
  7. aaronnorth

    aaronnorth Member

    Messages:
    3,955
    Location:
    worksop, nottinghamshire
    K2CO3 will raise the alkalinity, and some people may , or may not want that, just a matter of preference really,
    if you do want to raise the alkalinity, then you again have 2 choices... K2CO3 or NaCO3... it just gives you different options
     
  8. Cro

    Cro Member

    Messages:
    103
    Cheers Aaron :thumbup:

    I fear I may have been editing my post above removing the question about K2C03 whilst you were typing your reply though, sorry. :oops:
     
  9. aaronnorth

    aaronnorth Member

    Messages:
    3,955
    Location:
    worksop, nottinghamshire
    doesnt matter hehe,

    what size tank is it?
     
  10. Cro

    Cro Member

    Messages:
    103
    240ltr
     
  11. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    Hi,
    While Keymaker raises an interesting point, I'd have to say that I've never seen a difference when adding K2SO4. This is whether using either tap or RO. K+ is also being added with KH2PO4, though not nearly at the same levels. A 13-23ppm K+ level should not cause any grief unless the lighting is absurdly high, in which case one is much more likely to see N and/or P starvation first. The Barr suggested K+ range is broad, 10-30ppm with little difference demonstrated between low and high. I have no idea what "PPM Balance" is so I can't address that concept. If the concept is based on symmetry of mathematics in a spreadsheet then this is completely arbitrary.

    Secondly, the seemingly age old nitrate witch hunting mentality seems to be still in effect. Who has had a fish/shrimp die of nitrate poisoning? Or was it a death that was simply attributed to high nitrates for convenience?

    40% of a KNO3 molecule by weight is K+ and 30% of a KH2PO4 molecules is K+ so I see no reason at all to buy a third K+ product. One of the basic ideas of EI is simplicity. So that's the reason not to buy K2SO4. If you think you have a K+ deficiency, which, again is highly unlikely, then the first step is to add more KNO3 and see if this make a difference. 99 times out of a 100 you'll find that the deficiency is actually CO2 or a flow/distribution issue. The OP seems to think there is a K+ deficiency, but what is this assessment based on :?: Adding complication just adds another round of ammunition for the EI haters out there. :rolleyes:

    Cheers,
     
  12. spider72

    spider72 Member

    Messages:
    116
    Location:
    Wick, Scotland
  13. Cro

    Cro Member

    Messages:
    103
    Thanks very much for everyone's input so far.

    I have worked out what I should be dosing as per http://www.ukaps.org/EI.htm My tank is 3.15 times 20 gallons so my macro nutrient mix should be the following added to 600ml water, 50ml doses 3 X per week;

    KNO3 = 7tsp
    KH2PO4 = 2.5tsp
    MgSO4 = 19tsp

    I'm not dosing 19tsp of MgS04 as when I first worked out my mix I thought I'd made a mistake and added 6tsp instead :oops: :shh: So I'll have to rectify that.

    Now as I have a high fish stock in my tank should I replace some of my KN03 with KH2P04? My water report suggests I am supplied 36ppm if Nitrate already :crazy:
     
  14. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    Hi,
    Yes, fundamentally the numbers look fine. Here are some finer points that may either clarify things or confuse you further:
    Remember that this is the "estimative" index so there is no way you'll enhance your accuracy by accounting for that 0.15 size factor. Just call the tank 3X as large and let the rounding of the fractions take care of you.

    19 teaspoons of MgSO4 is a lot, I realize that, and that's used as a worst case scenario. If your water report reveals that your tap has plenty of Mg then there's no need to up the dosage from 6 to 19. Again, EI is an interactive procedure. It is not meant to be rigid. It's for the thinking aquarist and NOT for the Lost in Space Robot Automaton.
    For example, you can easily change the MgSo4 dosage to 19 and see if there is an improvement in growth rates. If there is no discernible enhancement then that means your 6 teaspoons will suffice. When it comes to the micronutrients like Magnesium, Iron, Calcium and so forth, you have a tremendous leeway because the plants don't use very much of these elements, they just need to be present, but not necessarily at high levels.

    On the other hand Carbon, Nitrogen, Phosphorous and Potassium (CO2 + NPK) are vital and are used in large quantities. All critical functions in a plant, such as food production and storage, photosynthesis, protein production, DNA/RNA synthesis, involve these four. If you have algae, it's because your have poor effective levels of some or all of these, so I don't trust any water report values for NPK. Unless the municipality tested your specific water line, the value could just as easily be 3.6ppm NO3. So with macronutrients, start your dosing as calculated for about 3 weeks or so and ensure that you do not suffer malnutrition. Then make up a new batch with say, a 10% lower KNO3 dosage and use up that batch. If you don't see evidence of Nitrogen starvation , such as BGA, then on the next batch lower the KNO3 by another 10% and use that up. Continue this iteration and you'll find that at some point your start to see a nibble of malnutrition, perhaps some BGA or some yellowing on mature leaves. this tell you that you have gone too low on Nitrogen reduction, so just return to the previous level.

    So instead of chasing voodoo test kit readings, you allow the tank to tell you what the status is and you can take appropriate action. You never really need to know exactly what the tap NO3 value is. You only need to know that "tap + X dosage of KNO3 takes me where I want to go".

    As Keymaker rightly points out, you may be able to drive the KNO3 dosage so low, due to tap water NO3 content, that you would then need to supplement K+ and that's when you may need to supplement K2SO4. Again, I personally have absolutely no fear of KNO3, so I never even think about what's in my tap or what's in my fish waste. I just carry on as if the tap NO3 content and NO3 due to fish waste were zero. This means I never suffer problems with K+.

    What you do need to ensure if you have high stocking levels, is that you perform massive water changes, and that when you do the water change, you scrub and rub and keep the tank + filter(s) immaculate. Get rid of as much fish poop and organic waste (brown detritus) as possible because that is what kills fish, causes algae and stunts plant growth in a high tech tank, not inorganic NO3.

    Cheers,
     
  15. Cro

    Cro Member

    Messages:
    103
    Thanks for the informative reply. :thumbup:

    What I'll do is go back to stage 1 I think. When I first started EI dosing I was trying to take everything into account and changed the dosing quantities to what "I" thought was best :rolleyes: So this weekend will be a big clean out of all algae, affected plant leaves and just in general really, I don't know how to clean the substrate now to be honest with it being covered in various types of grass, guess I'll just have to work that out. I'll make up new dosing solutions and give it a few weeks to see what the results look like, if it looks like I still have a deficiency in K+ then I'll play with K2S04 and see if that helps. My growth rate has been slower than I expected so maybe the MgS04 is to blame, or maybe it is as you say a combination of everything. I have also fallen into the trap of doing 50% water changes every other week, this has obviously made things worse so that will be addressed also.

    Just to pick up on the filters. I clean them thoroughly every water change, media, sponges and canisters and pipes too. :thumbup: All done in tank water of course.
     
  16. keymaker

    keymaker Member

    Messages:
    255
    Location:
    Budapest, Hungary
    I have.
    It was not EI though.
    It was TPN+ (low on K). I had to compensate with K2SO4 to get rid of deficiency - I was succesfull at that. I made no other changes. It was a cycled tank, proper CO2 dissolving and distribution, etc.

    I remember you told me once something like that the EI dosage quantities should not be accepted by the parliament. :)

    I agree that 23ppm K level should be fine. "PPM Balance" is indeed something I personally came up with - when doing my excel calculation. It is absolutely NOT based - as you call it - "on the symmetry of mathematics". It is based on the knowledge that levels of each nutrient have to be calculated and considered separately, and plants can not substitute one nutrient with the other --- and algae can bloom even if all nutrient levels are OK - except one.

    Additionally I must confess that I am not very good in this "art" thing when mixing and dosing according the EI method. Really --- to keep it simple I just decided that I will keep ALL levels at the top of the EI range, or a bit above, to be on the safe side. I have the knowledge and tools to have precise (to the exact PPM) levels of ALL nutrients together and it does not require additional effort from me to do it.

    So I do it. I just get the powders and mix them... The K2SO4 does not even cost a beer's - something you also told me to go get for the money I was planning to spend on some unnecesary thing in the past :D. Go for 30 ppm NO3 AND 30 ppm K instead of 23? Yepp, why not. Overly precise? Probably. But then it seems more simple for me to think this way. I just let them "go together" with the dosage - in balance. Oh, and also do not forget that I am using a self-made all-in-one solution.

    But in general - the way one should view things and approach the EI - I would be certain to follow the "estimated" approach of things.

    Oh, yes, I completely agree. Most of the time it is CO2. And with proper KNO3 and KH2PO4 dosing you would indeed probably not need K2SO4. Unless you're like me, I'm just plain lazy to measure, think and re-check. So I keep ALL levels (including K with the addition of K2SO4) at the top. As easy as that.

    I have another point in the MgSO4 dosing topic: do not forget, that some of the Micro trace chelates (the widely used EDTA for Fe in particular - it is sold in the UK) are known to have caused some Fe precipitation (reaction with P) in hard-water environments. Defdac from Sweden reported that for example. Hardening of the water to a higher point does no harm to the plants - but the filter toxication does affect the nitrification process and algae bloom.
     
  17. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    Aha, OK, that makes sense. But that also makes a difference. The basic principle is that if you are dosing the EI levels of KNO3 then you have enough K+. This principle applies whether you are using Hungarian, Chilean, British, RO, Egyptian, or even Mesopotamian water.
    Haha, :clap: Yep that's right - but the idea is to establish the baseline. By the OP's own admission, he had arbitrarily deviated from the baseline numbers, had problems, and then just assumed that adding K2SO4 was necessary to fix the problems. I deduce that he started the thread thinking that the unauthorized deviations he made had nothing to do with his problems, and that because K2SO4 was not specified in the dosing schemes then K was the issue. I'm trying to recalibrate this thought process. Once the baseline is established, and once the issue of malnutrition is resolved, one can then easily deviate to fit the tanks unique properties. If the OP resets the tank, implements the baseline numbers (whether he uses my numbers or your spreadsheet) then in a few weeks he ought to be back on track. ;)

    Aha :!: - OK, well I've been informed by the Romulan Council that adding "PPM Balance" to the EI dictionary definitely requires Parliamentary approval. :woot:

    I understand that mate, but what if someone doesn't know Excel spreadsheet? Or is unfamiliar with your personal expressions such as PPM Balance? We're trying to troubleshoot someone's tank located thousands of kilometers away. What's simple for us may not be simple for the OP. Simplicity involves not only a reduction in calculation (which you have executed brilliantly on the Excel) but also a reduction in the number of things to do. Adhere to the fundamental principles. Buy only the minimum items you need. Dose the baseline values. Reassess from there.

    The OP had no difficulty whatsoever figuring out that he can multiply the baseline 20G dosing values times 3 to determine the baseline dosage for his tank. Some people find it easier to do it this way while others prefer to use your spreadsheet. Others use the Nutricalc or JamesC's All-in-One. This is not a big deal and it's also why Ben & Jerry's makes 64 flavors of ice cream - something for everyone. The issue here is that none of these calculation methods really solves his problems if he doesn't fundamentally understand that he should stick to the numbers first, allow the tank to determine how and when he may deviate the dosing, and good grief - change the water occasionally! 8)

    Cheers,
     
  18. keymaker

    keymaker Member

    Messages:
    255
    Location:
    Budapest, Hungary
    Nothing to add here, I'm with you on the necessity to simplify things. :idea:

    I have asolutely no idea what you mean by flavor diversity though. ;) We do not have Ben & Jerry's here - but I'll make sure to assault one next time I'll ravage the overseas anglo-saxon lands. :D Now that I acutally wrote these they fought back in full force, their site actually crashed my Mac's Safari so I had to retype this post. :) The war is on!
     

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