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FAQs on Calcium and Alkalinity in Seawater, Science 

Related Articles: Calcium and Alkalinity Explained by Anthony Calfo, Calcium, Biominerals, The Use of Kalkwasser by Russell Schultz, Calcium Reactors, Marine Maintenance, Marine Water Quality, Magnesium in Seawater, Strontium in Seawater, pH, Alkalinity, Marine AlkalinityLive Sand, Marine SubstratesReef Systems, Refugiums

Related FAQs: Ca/Alk 1, Ca/Alk 2, Ca/Alk 3, & FAQs on Calcium & Alkalinity: Importance, Measure, Sources, Use of AdditivesTroubleshooting/Fixing, Products, &  Calcium, & FAQs on Calcium: Rationale/Use, Calcium Measuring/Test Kits, Sources of Calcium, Calcium Supplements, Dosing, Chemical/Physical Interactions, Troubleshooting/Fixing, & Calcium Reactors, & FAQs on Calcium Reactors: Rationale/Use, Selection, Installation, Operation, Media, Measuring, Trouble-Shooting, By Makes/Models, & pH, Alkalinity, Marine Alkalinity, Marine Alkalinity 2, Marine Alkalinity 3Marine Supplements 1,

A nice DIY Calcium Reactor system by Mike Liesman in San Antonio.

Where does the calcium go? 6/7/12
Good Evening Bob,
<Hello Eric, James with you today.>
About a month ago I upgraded my 90 gallon tank to a 125.  The only good thing that happened is everything has survived.  Ever since the new tank as been running I have not been able to get my parameters where I need them to be.  Currently my calcium and Alk are Low.  The Alk is 6.8 dKH and the cal is 380.
<Is not dangerously low.>
 I am also running an Aqua C calcium reactor and use Kalk in my auto top off.  I have been trying to use buffers to raise the cal and Alk and within  20 minutes the levels fall back down to where I started.
<Mmm, not a good idea to dose these buffers together.  Best to let the reactor supplement the calcium naturally in your case. Where calcification is concerned, these two values are intimately related (one affects the other) and supplementing together can lead to an undesired imbalance between calcium and alkalinity.>
My tank also has a low ph 7.7-7.8 which I am assuming is due to the low Alk.
<Is the reading from a color comparator type kit or electronic?>
Do you have any ideas what may be going on?
<My first thought is that the pH isn't low enough in the reactor, not enough CO2.  Have you tested the pH of the effluent?  A reading between 6.5-6.7 will generally give the best results. Too low a pH will turn the media to mush, and too high a pH won’t dissolve the media.  An electronic pH meter is highly recommended for this test.  Color comparator kits are just ball park figures, not accurate enough.>
Can a new sand bed cause this?  CaribSea base rock?
<The carbonate present in the sand should actually help raise the dKH but since it is new, it may take some time as it does dissolve slowly.>
<You're welcome.  James (Salty Dog)>
Sent from my iPad
<Sent from my man cave.>
Re Where does the calcium go? 6/7/12

I actually sent over the wrong email which was from a few months ago.  Can you please see below?  Your help is greatly appreciated.
I am hoping you can help. A few months ago I setup a single stage calcium reactor. Due to space limitation I had to pass on getting a 2 stage to gas off the effluent. I was able to dial in the reactor after a while but pretty much had the reactor maxed out. The ph was 6.3 and my effluent was wide open. Obviously this eventually dropped my ph to mid low 7.7's at night and low 7.8 during the day. A few of my corals started to show signs of stress so I had to cut the reactor back after Kalk in my auto top off failed to raise the pH. My pH in the tank is now stable, 7.9 at night and 8.0 during the day. I ended up setting up my dosing pumps to drip 2 part in small increments every few hours.
<Re the first thread, you need to dose part A and part B on alternate days.>
My Alk has been rock solid at 10dKH but my calcium continues to fall by almost 50ppm's in a day. According to the bottle of the part A I would have to add 390ml of calcium to cover the drop. This amount seems crazy since only 80ml of Alk keeps the number is in line.
<This is one of the reasons I am not a big fan of two part dosing.>
 I tested my magnesium which was at 1280 so there is no issue there.
Any idea what gives here?
<Try dosing each part on alternate days, give it a week or so and see if there is an improvement.  If not, I
suggest trying Tropic Marin's Alka Balance.  See here.  http://www.tropic-marin.com/web/english/homepage.html
I have used this product in the past and was quite pleased with it.  Once my present stock of calcium/dKH buffers are exhausted, I plan on going back to this product.  I will forward this thread to Jason at Aqua C regarding the reactor and ask for his input.  James (Salty Dog)>
Re Where does the calcium go? 6/7/12

Thanks James.  Jason hope all is well.
<You're welcome.  James (Salty Dog)>

Dosing Question -- 2/8/07 <Hi Scotty, Brenda here tonight> First of all, let me say you guys are the best!!! <Thank you!> Now, I searched the forums and got some of my answer to this question, but need you to finish it. <I'll try> I add part 1 and part 2 of the Oceans Blend calcium and alkalinity supplement.  I have added over 48 ml in the last 72 hours, but my test kit is showing no increase in calcium (stays at 350ppm).  My pH has been rising, even though I have added an equal amount of part II (alkalinity).   <I need actual results of pH> I do not have an alkalinity test kit yet (will get one soon), so I have no idea to see where that is, and am basing any decision I make on an unknown. <Yikes!  Please stop!  You will also need a Magnesium test kit.  Mg should be in the 1300 -- 1500 ppm range for everything to balance properly.> So my question is should I continue with both parts until my calcium gets to 400 ppm. <No> Should I use one for a few doses without the other as a way to balance out the pH?  Or should I just sit tight and let things get settled? <Sit tight until you get some more test kits.> Best idea is to listen to what you guys <or gals> have to say. <Never dose calcium, alkalinity or magnesium into your tank until you know what your levels are.  Please read for a better understanding:  www.advancedaquarist.com/issues/nov2002/chem.htm   www.reefkeeping.com/issues/2002-04/rhf/feature/index.htm www.advancedaquarist.com/issues/oct2003/chem.htm www.reefkeeping.com/issues/2005-03/rhf/index.php#3   Also, here is a calculator to help you with dosing.  It sure makes my life easier:  http://home.comcast.net/~jdieck1/chemcalc.html > Scotty, NY <Good luck Scotty, and be patient!   Brenda>

Striking A Balance Hi, <Hello- Scott F with you!> I just have a quick question. Can alkalinity ever be too high ? I tested my calcium level and right now it is about 350 (test only measures in increments of 50). I was told by my local fish store that if my calcium is only 350 then alk can never be too high and that if I added buffer every day it would be fine? Does this make sense. How often should I add buffer? <Well, any substance that you add to the water, including buffers and Kalkwasser, requires testing to verify not only that the amount that you are adding is appropriate- but to see if it is even necessary. Just adding buffer or other additives without supporting water testing is a bad "habit" to get in to, IMO!> They told me to put in every day to maintain current level . This does not seem to be correct in my opinion. I was under the impression that if I dosed Kalk, this would maintain alk, and that the higher your alk is the lower calcium will be. Thanks <Well, your LFS seems to have made a very generalized statement. The calcium/alkalinity dynamic is somewhat confusing and often misunderstood. Suffice it to say (and here I am generalizing!) that a very high calcium level often has an accompanying moderate alkalinity level. You really cannot have both high calcium and high alkalinity at the same time...As Anthony eloquently points o ut with his "marble analogy" in his "Book of Coral Propagation", a given quantity of water can only "hold" so much, before something has to "fall out" of solution. The best thing that we can do is keep a "balance" between the two factors. Remember, too, that we tend to get really fixated on specific readings as our "target", and sometimes forget to just look at the aquarium...Your animals will let you know if your calcium level is sufficient, through growth and overall health. Do a little reading on the WWM site to get a better understanding of the calcium/alkalinity dynamic...You've got a good idea so far- just keep reading up on it! Good luck! Scott F>

- Calcium & Alkalinity - Hey Steven Pro <Hello, JasonC here today...> I try and not ask to many question or take you guys for granted. But sometimes I just need a little clearing of the facts. And I did check your FAQs. <Ok.> Can you explain the calcium/alkalinity relationship? <Not very well in a brief email... the quick answer is that at high levels, they are mutually exclusive.> I don't mean the whole thing. I don't need numbers or specs or formulas. Just why does it seem alkalinity goes down when calcium goes up? <Uhh... you've asked the loaded question to which there is no simple answer.> Although I don't think it really does go down. There must be some symbiotic relationship. <They are not symbiotic.><<Are more "antagonistic", mutually-exclusive... though both necessary. RMF>> I just seem to be missing a piece in the puzzle. <Please read here: http://www.wetwebmedia.com/calcalkmar.htm > Thanks, Bill <Cheers, J -- >

Dynamic Dynamics of the Calcium Alkalinity Dynamic Hey guy..    hope this question finds you all doing well. <Just dodged a round of layoffs at work, can't complain.  Maybe it's time to move on.> I found  a site stating that the balance to an Alk level of 4 meq would be 440 ppm Ca . Does this sound ok with you enlightened folks.. <My search for enlightenment, hmm... I do need to get back to that, but for now lets talk Calcium and Alkalinity.  4meq Alk is a fine hardness, when your Ca gets up around 440ppm you will want to watch for creeping and spikes, 440ppm is towards the top of the scale too much higher could cause precipitating Alk.>  Rush is talking about you guys when he says "Knowledge on loan from God" hehe .. <Ha, simpler than that, people sharing is a good thing.  Check out the following link for a good article on the relationship between Calcium and Alkalinity. -Gage   http://www.wetwebmedia.com/calcalkmar.htm >   keep up the good work. <Will Do.>

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