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  1. #1
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    water change affect Ca levels?

    I got my Ro/Di unit a few weeks ago and since then I've done a 15g water change last weekend and another 15g water change this weekend that just past.My calcium has droped from 360 to 340 but my alk is still at 9.
    Is this normal ?
    should I just keep driping kalk or maybe add a calcium additive?

  2. #2
    liv
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    Former Moderator liv's Avatar
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    its normal to have those drops.. i had the same issue.
    I drip kalk and add turbo calcium every morning.

    moving.. so temporarily out of SW :b8:
    planning next tank, possibly 60x30x20 on 2x plasma.
    updated: 2011/05/30

  3. #3
    Senior Member nbreau's Avatar
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    I've been able to keep my calcium at a good level of around 400 by adding Kent Calcium but my alk seems to drop unless i am continuously adding kalk.
    ======================
    sold the 77gallon back in 2005, looking to setup a nano

  4. #4
    Senior Member Flame*Angel's Avatar
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    Salt mixes are notoriously low in calcium. Even if you don't have many calcium using corals if you don't add any extra calcium and alk the levels will drop over time. You can just add the extra calcium and alk to the new water before the water change.
    Susan

  5. #5
    Senior Member GoSUV's Avatar
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    Most salt mixes are low on Calcium because they expect you to use dechlorinated tap water to mix it. Tap water invariably contains some Calcium so that makes up the deficit. If you RO/DI your water first and add your salt to it, you end up with lower Calcium.

    I would add the Calcium (Turbo Calcium) to the tank AFTER the water change. Adding Turbo Calcium to the change water causes the pool to shoot up in Ca, driving down alk. Because a mere spoonful of Turbo Calcium can be amazingly effective. Unless you are doing 50 gallon water changes, it is hard to measure the exact amount, i.e. how many drops, of Turbo Calcium to add.
    If the authors of "Finding Nemo" knew anything about Clownfishes, Marlin would turn into a female and Nemo would become her new husband.

  6. #6
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    I think the majority of people use RO/distilled water for their tanks now and I'm sure the salt manufacturers have taken this into account.

    If I remember correctly Randy Holmes-Farley wrote an article where they compared normal sea water to the various salt mixes. Most of us keep our Ca above normal sea levels to promote coral growth. I'll see if I can track down that article.

    Vickie

  7. #7
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    I didn't find the article I was looking for but here is some data -
    In this article - http://reefkeeping.com/issues/2002-0...ure/index.htm, Ronald Shimek compares natural sea water to various aquariums and makes this statement in the conclusions - "In most cases, it appears that about the only similarities that Reef Aquarium Water has to Natural Sea Water is that they both are wet, and they both contain somewhere in the range of three and one half percent (or 35%) salt by weight. It can truly be said that very little else is similar. ... A significant reason for this problem is that the basic water obtained when artificial salt mixes (see Atkinson and Bingman, 1999 and the IO data in this study) are prepared bears very little similarity to NSW, but even aquarists using NSW as the initial medium don't have tanks where the chemical composition bears much similarity to Natural Sea Water. "

    This article http://reefkeeping.com/issues/2003-0...ture/index.htm lists the Ca of various salt mixes -
    Instant Ocean - 361
    Bio-Sea Marinemix - 430
    Coralife - 405
    Marinemix Bioassay - 410
    Natural Sea Water - 412

    These values were taken from reports from 1999/1998. I seem to remember reading more recent test results since some of the manufacturers have changed the composition. I can't find the newer report.

    In all cases fishy_business, your Ca should have stayed the same or increased since the lowest Ca you would be adding is 361.

    Looking into your readings further - Ca & alk should be balanced. Using the calculator here - http://www.kademani.com/reefchem.htm (I converted your alk of 9 to 3.2 meg/l), for alk of 3.2, your calcium should read 424. When they are out of balance, things happen - like percipatation. This article explains some of that http://reefkeeping.com/issues/2002-0...ure/index.htm. Dripping kalk (a balanced additive) won't help bring Ca & Alk into balance. You will need to add Ca alone to bring them into balance. Here is where the calulator helps. It tells you how much of various additives to add to bring the Ca into balance. Here is another good article on keeping your Ca & Alk within the recommended values - http://www.advancedaquarist.com/issues/nov2002/chem.htm

    One thing that I will add here is - magnesium. I could not get my Ca above 400, not matter what I did until I brought my mag up to 1300. Do buy a test kit and check for this before adding any.

    Vickie

  8. #8
    Senior Member nbreau's Avatar
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    wow, great post !
    ======================
    sold the 77gallon back in 2005, looking to setup a nano

  9. #9
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    Thanks fellow hobbiests! listening to people who have been there and arent trying to sell you something always seems to pay off.The one thing that has crossed my mind could be my test kits.I am usung a Hagen calcium test kit and a Aquarium Pharmaceuticals inc Alk test kit.Both are relatively cheap to buy and that may be a reason,however according to the tests before the water changes I was reading 360ppm Ca and now its telling me 340ppm..Alk has gone up from 8 to 9. and I'm using Crystal sea marine mix salt.

  10. #10
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    In my opinion, Salifert test kits are one of the easiest to use. Most people that I've talked to (and read on the forums) rate them very highly for accuracy.

    One way of checking your readings is to ask a fellow hobbiest to use their kits (different brand preferrably) to test your water. This will either confirm your readings of leave you both wondering which test kit is correct. LOL Some stores will do this for you as well.

    Vickie

    PS I'm not familiar with your brand of salt. I use Instant Ocean.

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