Low Alkalinity

Discussion in 'General Discussions and Advice' started by Sentari, 25 Jan 2010.

  1. Sentari

    Sentari

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    Hi Hennie

    Was wondering if you could sum this all up for me.

    I decided to test my parameters again after some time not really worrying about anything. The reason for me testing my parameters is that my coraline started dissapearing all over and my Zoa's dont seem to colour up like they used to.

    Okay so my alkalinity is sitting at 5dkh. PH 8.2 and all other parameters are in check.

    Okay this is my dosing regime and maintainance regime.

    I dose 2 tablespoons of slaked lime whenever i fill my RO water. Which is usually once a week.
    I dose 1 cap of iodine tincature which is mixed with 400ml of RO water every 3 days.
    I do a water change every 2 weeks.
    I clean one of my screens on my algae scrubber every 2 weeks.

    What i did last night is mixed 4 teaspoons of baking soda with RO water and added that to the sump. my tank is 300L.

    I was just wondering if i'm doing the right thing there.

    Another 2 things. How do i keep everything in balance. Also is it a good idea to bake the baking soda in the oven if my PH is sitting at 8.2.

    Also how should i dose my calcium? I went and bought some brightwell aquatics Kalk+2.

    Sorry if its all over the place but 101 questions and FAR tooo much thinking :)
     
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  3. Francois

    Francois

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    Hi Sentari

    Sitting with the same problem...Had nice coraline grow and then it all disappeared. I think its the algea scrubber and its draining the alkalinity.
     
  4. jacquesb

    jacquesb Retired Moderator

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    Good morning Deon - your dosing regime seems 100% to me. Can you just please elaborate on how "big" the cap is that you are using for dosing the iodine? (plus/minus)....

    You can perhaps increase the dosing of your kalkwasser/slaked lime - ie. mix 3 tables spoons, and split the amount of RO water in halve: ie. 150ml per 2 table spoons of slaked lime (times 2) - then dose this twice a week....

    It is possible that your corralline algae is consuming more of your calcium that what you are dosing. Once your calcium levels are low, the corralline algae could possibly start lowering your alkalinity........

    I would also suggest doing the same with sodium bicarb (baking soda) - you can mix the sodium bicarb with the same 150ml RO water which you are mixing the slaked lime with.

    Just take note that the 2 table spoon slaked lime + RO mixture would be quite high in alkalinity - so - you SHOULD dose / introduce this very slowly to your tank - preferably in a high flow area - and dose over a period of an hour..... else your alkalinity might just shoot up too fast in your tank water, causing some major problems....
     
  5. Sentari

    Sentari Thread Starter

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    I dosed the baking soda in a cup of RO water and chucked the whole cup into the return of my sump. I dont see this being a problem.
    Question.

    Should i bake the baking soda if my PH is 8.2 or should i just leave it. I have read you only bake it if your PH is low.
     
  6. jacquesb

    jacquesb Retired Moderator

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    Hi Deon - no. You don't specifically HAVE to bake your baking soda. If you bake it, you get sodium carbonate (whereas baking soda is sodium bi-carbonate).....

    The pH of sodium bicarb is 8.2. Which is more than good enough for your tank.

    And no - it is not a problem a.f.a.i.k the way that you dosed your bicarb....
     
  7. Reef Maniac

    Reef Maniac MASA Contributor

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    Yes, but...

    Each tank has it's own, individual calcium and alkalinity demand, and these can vary quite dramatically. Although in theory the calcium and alkalinity demand is linked (as the corals and coralline algae's uptake of calcium and carbonate is in a fixed ratio), in practice a tank will always consume more alkalinity than calcium - mainly because the alkalinity also reacts to neutralize the organic acids and carbolic acid (from CO2...) present in the tank water. It is thus (IME) quite natural for a tank to have it's alkalinity slowly drop over time, even though the calcium level may stay stable.

    One of the better ways (IMHO) to add both calcium and alkalinity to a tank is to add lime water. This should, however, be done by slow dripping (or, if highly experienced, by direct slurry injection), but should not be added in relatively large quantities at any particular point in time (e.g. by pumping (say) a few liters of RO+lime into a tank at one go to top up the sump). The reason for this is that the pH of the tank water is increased quite rapidly at the point where this water is added, and the high pH then causes calcium carbonate to precipitate out of solution, thereby actually reducing the alkalinity and calcium levels. I don't know how rapidly your RO water is addd to the tank, and if done very slowly might not be a problem, but I just wanted to give a general warning about this practice...

    One would like to make the concentration as strong as possible, in order to add as much alkalinity and calcium as possible. Unfortunately, slaked lime is not very soluble in water. One should thus add more slaked lime powder to the water than what would dissolve, in order to ensure that the limewater solution is always saturated. The amount of slaked lime needed to ensure a saturated solution would vary with pH and temperature of the water. A general rule of thumb is to use about two teaspoons (10ml) per gallon (4.5l) of water, but using more powder would not have any disadvantage other than a slight waste of powder (and money...). One fairly accurate way to check if the solution is concentrated is to measure the pH of the solution. At 25°C a saturated solution should have a pH of 12.54.

    Just to be on the safe side, I would rather add a third tablespoon of powder in your 20 liter drum of RO to ensure that the water remains saturated with lime...

    If your alkalinity demand is higher than the maximum lime water solution you could add, you need to either treat the lime water with vinegar (to increase the solubility of the lime and reduce the pH of the solution), or you need to add an alkalinity buffer such as baking soda.

    I would recommend that you first determine the tank's alkalinity demand. Do this as follow:
    • Increase the alkalinity to approximately 8dKh
    • Do an accurate alkalinity test about 24 hours after the alkalinity has reached 8.
    • Stop all calcium and alkalinity additions/supplementations for a period of 48 hours.
    • Test for alkalinity at the end of the 48 hour period
    • Subtract the second reading from the first, and divide this reading by 2 - this will give you the average daily alkalinity demand.
    • If the alkalinity has not dropped measurably during this 48 hours, repeat the process, but double the time to 96 hours and divide the end result by 4
    Once you have your tank's alkalinity demand, it's pretty straight-forward to calculate your alkalinity supplementation requirement. Saturated limewater contains approximately 40.8 meq/l of alkalinity. So, if your tank is 300l (total water in tank and sump), and the demand is (say) 0.5dKh per day, you should be adding 300 x 0.5 x 2.8 (factor to change meq/l to dKh) / 40.8 = 10.25 liters of saturated lime water per day. If, due to a lack of evaporation, or an unacceptably high increase of tank pH, this is not practical, you would have to calculate what your actual alkalinity supplementation via the limewater is, and then add the difference between the total demand and the limewater supply by some other means, be that via calcium reactor (ideal), baking soda additions, ot the addition of vinegar to the lime water (with an increase of the amount of lime powder used...).

    Just keep in mind that a continual addition of only baking soda will upset the ionic balance of the water. You would have to balance this with the addition of calcium chloride, and a mix of magnesium chloride and magnesium sulphate (Epsom salts).

    Keeping everything in balance is one of our greatest challenges. The best way would be to do regular partial water changes (with perhaps one or two larger changes every year), and to use both lime water additions AND a calcium reactor. Alternatively, use a balanced, two (or three) part additive - either commercial, or DIY (search the web for Dr. Randy's DIY two-part additive, or check the sticky articles in my forum...)

    The use of baked baking soda is only necessary if your tank's pH is inclined to drop, as will happen as the tank ages - until then the "normal" baking soda will be fine.

    Hennie
     
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  8. Warr7207

    Warr7207

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    Something doesn't sound right here.

    If you dosing Limewater, it will drive both Alk and pH up.

    If you dose Bi-Carb it will drive your pH down and Alk up.

    Your tank is going get chemically unbalanced.

    Go with a solution that solves your problem.

    Have you looked at your Ca Levels ?

    IMO: Baked Soda works better with Alk addition.
     
  9. Sentari

    Sentari Thread Starter

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    Thanks a stack Hennie for taking the time to help. I am doing exactly what you said. I tested my Alk last night and it was at 6 dKh. Which means the Alk is climbing. I then dosed some more baking soda. I will test tonight when i get home. I dose this also right before the lights go out.

    Once all my parameters are in check i will get the LFS to test my Ca or buy a Ca test kit and see where my levels are.

    Warren no i havent. I need to get those tested. I know there is a problem there but at the moment i would rather get the alkalinity right then tackle the Ca.

    I purchased Brightwell's Kalk+2 and that should give me everything i need :)
     
  10. vatso

    vatso

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    Hi Sentari I was looking at Brightwell's Kalk+2 but was worried as to how much of everything is in each scoop & rather went the Brightwell's CA, MG & Kh powder.

    Let me know how it goes would be great to rather mix one product then three

    Mark
     
  11. Sentari

    Sentari Thread Starter

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    Okay so the alkalinity has climbed to 7dKh which i'm REALLY happy with!

    I dosed again last night and will be checking again tonight.

    I will then leave it for 2 days and test again and see my consumption. I will then start testing my Ca and dose Kalk while testing both alkalinity ph and Ca.
     
  12. gaboon

    gaboon

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    Hennie, thanks, that was very helpful!
     
  13. Adee

    Adee

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    As Hennie said, pinpoint your daily use and work backwards to calculate what u need.

    I use the balling method and this online calc has helped out a lot:

    Reef Chemistry Calculator

    Get yourself a digital scale that mearsures to the gram, then u take your daily alk (bicarb) requirements, times it by 7 (week) and mix with 7 litres of water....then dose 1L of the mitxture to your tank daily. Or if your demad is not that great...mix it with 3.5L of RO water and dose 500ml everyday.

    the trick is nailing what your system uses up every day....u can do the same with calcium and mg...also you night have to recheck 24hrs after a wc as some brands would spike your baseline reading for the week ahead so you night skip dosing for the couple of days following a wc.
     
  14. Sentari

    Sentari Thread Starter

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    Thanks for the help Adee. Think its time to save up for a CARX. Dont think i have enough corals for the demand.

    Alkalinity is now at 8. I will monitor it for a day or so then i will start adding Kalk.

    Tested the PH also and its sitting at 8.4.

    It went up 0.2. but dont think this was from the dosing of baking soda Think it might have been from the water change i did this weekend :)
     
  15. Adee

    Adee

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    Or get a contrable dosing system with 2 pumps (like me) and supplemented with a kalk stirrer.
     
  16. Sentari

    Sentari Thread Starter

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    My next question what would be the easiest way to balance everything? Also the cheapest and also taking into account the accuracy etc.
     
  17. Adee

    Adee

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    There has been some discussions on this, I think Junz posed the exact question.

    Like everything "it all depends" how far/serious u willing to go in this hobby. Do u you buy whats best for now/pocket...or whats best for the day u get that 2000L "I always wanted" system.

    Seemingly when I was told on day one what I needed to get...I eventually got the exact same stuff some 6 years later, at the cost at that time...I simply could not correlate the two and justify the expense. Little realising in that period for what I paid in upgrades or doing things the wrong way....had I saved up would have bought the kit 3-4 time over.

    The trick is where u want and see where u want to go with this hobby. Ok, I'm rambling here...short story, what fits best for your pockest best for the absolute long haul.
     
  18. Sentari

    Sentari Thread Starter

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    Thanks bud i fully understand!

    And i can see you've been through all the problems already.
     
  19. Bob the (reef)builder

    Bob the (reef)builder

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    Guys, unless I missed it, nobody has said anything about Magnesium. Coraline is a great consumer of Mg.

    If your Mg levels are too low you can put as much Ca into your water as you like, it will simply attach itselt to the nearest Calcium carbonite structure it finds. It will also take Carbonates with it to do so. Thus adding Ca can actually lower your Alk and not increase your Ca in the water at all.

    Getting your Mg right first is very important. You might even find that CA and Alk increase with just this step.
     
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  20. Sentari

    Sentari Thread Starter

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    Thanks Rob.

    I have purchased Brightwell Aquatics Kalk+2 with has Mg in it. I will see how things go over the next few days.
     
  21. Bob the (reef)builder

    Bob the (reef)builder

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    Sentari if I were you I would acurately mesure your Mg (TM test kit works well) then if its low add a Mg specific additive. It may take quite a lot. A little Mg in the kalk probably won't remedie bad levels very well.
     
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