Help with calcium

[leezer]

So, I got my bottle of Reef Builder in the other day, but before adding any, I made sure to test for my Calcium and Carbonate Hardness (KH - which I just learned comes from the German word "Karbonathaerte"). Now, it is my understanding that KH and alkalinity are not the same thing, but that in reef tanks there is a fairly good chance that the two generally change in parallel with each other. If I'm mistaken, please correct me.

Now, my question is: How much Calcium is too much calcium if my KH reading is within the acceptable range or slightly below, but I'm using Reef Builder to keep it up? Is there such a thing as too much Calcium if pH and KH are being kept normal? And finally, is my excessive Calcium reading due to the overwhelming amount of live rock I have in my tank (3g tank with 6 pounds of LR, 5 pounds of live sand, and 2 pounds of GARF grunge)?

Thanks,
Jon

 

[jdieck]

Yes, you can have excess calcium with normal levels of alkalinity but it will not be caused by your live rock as live rock (mostly an aragonite crystal form of calcium carbonate) will not dissolve at normal aquarium water PH.
The most common cause for high calcium is either the use of unpurified tap water with high calcium, the use of a calcium only supplement or the use of a salt mix with high calcium content but low alkalinity content.
In some systems, specially newer systems with high level of nitrification, alkalinity may lower in proportion to calcium giving the impression of high calcium and low alkalinity but that process will not increase calcium.
Reef builder will maintain or increase alkalinity but will not add calcium.

Normal alkalinity levels should be maintained within the range of 7 to 11 dKh (2.5 to 4 meq/lt) while calcium within the range of 380 to 450 ppm.
Magnesium levels at around 1250 to 1350 ppm will help maintain a proper level of calcium and alkalinity as it prevents the precipitation of both to form calcium carbonate.

Regarding KH and alkalinity, KH is a measure of alkalinity. As strictly originally defined KH (or dKh) is a measure of the alkalinity provided only by the carbonate and bicarbonate components of the total alkalinity but unfortunately in the aquarium hobby and because most test kits that measure in dKh units actually measure total alkalinity (including alkalinity coming from Borate, Silicate, Magnesium Monohydroxylate, hydroxide and phosphate), the term of KH (dKh) is associated with total alkalinity so you can convert it directly to other measures of alkalinity. 1 meq/lt=2.8dKh=50ppm

Finally you need to test for calcium and alkalinity and get them within the recommended range then try switching to a balanced supplement that provide the same ratio of coral and coralline calcification of 20 ppm of calcium for every 1 meq/lt of alkalinity.
Balanced supplements are typically two part supplements, Kalk (limewater) or a calcium reactor that dissolves calcium carbonate.

 

[leezer]

This might sound a little dense, but I wanted to very it anyway. I presume dKh stands for deca-Kh, which would be equivalent to Kh times 10. Correct on this one? My test kit has me multiply the number I reach by 10 to get the Kh, so I kind of put 2 and 2 together to reach this one.

 

[jdieck]

<a href=showthread.php?s=&postid=13369671#post13369671 target=_blank>Originally posted</a> by leezer
This might sound a little dense, but I wanted to very it anyway. I presume dKh stands for deca-Kh, which would be equivalent to Kh times 10. Correct on this one? My test kit has me multiply the number I reach by 10 to get the Kh, so I kind of put 2 and 2 together to reach this one.

Sorry but not. The kit multiplication has to do with the tritration agent concentration and volume to the amount of it required to reach the end point for the tritration PH.

one dKh is interpreted as one KH.
The "d" in dKh refers to "degrees" of carbonate hardness.

 

[leezer]

Good call on that. I appreciate the clarification. It looks like my kit (Nutrafin by Hagen) measures in mg/L, so I used Hagen's conversion tool and found my hardness of 90 mg/L (which I knew was low) turns out to be 5.04 dKh or 1.8 mEq/L. However, you're saying my dKh should be in the 7-11dKh range, but Hagen recommends 5.88 to 7.0. I'm trying to figure out a reason for the discrepancy between the ranges so that I can keep mine at the best level for my tank. Any further explanation would really be appreciated. I know my hardness is low, so I'm slowly raising it...I'm just not sure what level to stop raising it.

Thanks,
Jon

 

[jdieck]

I would try to verify that readig with another kit, I will definitively do not trust a reading of 90 mg/lt. (way off)
Hagen kits are not distinguished for being reliable, besides insure you are using the procedure for salt water and not fresh water, I think the conversion of the reading are different. Are you sure you should multiply by 10 and not by 20?

For conversion try:

1 meq/lt = 2.8 dKh = 50 ppm = 50 mg/lt

divide mg/lt by 17.86 to get dKh.