Carbonate Hardness Too High

[ChrissyRay]

My husband and I have maintained a small 5 gallon tank for three months now. In it we have two small fish, two feather dusters, a xena, and a cleaner shrimp. Last month, we started to add Calcium to the tank after it tested low (360-380) on several occasions, while everything else tested normal. For the first three weeks it was added every other day with no changes in the calcium level. We upped the dose to every day for the past week and still calcuim remains 360-380. Hardness on the other hand has sky rocketed. It has jumped to 18-20 on several occasions causing problems with the xena. Hardness has only been lowered through agressive water changes. No other chemicals/substances are being or have been added since we first set up the tank. Our fish dealer is stumped on how this could be happening. He has explained that carbonate hardness and calcuim are used together in the tank. However, when hardness gets to high it draws the calcium out of the solution which would explain our low levels of calicum. We are adding calcium every day and only seeing a rise in hardness. Any ideas on how to raise calcium while lowering carbonate hardness and solve this problem? Any help would be much appreciated.

 

[Randy Holmes-Farley]

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Welcome to Reef Central and the Reef Chemistry Forum.

What salt mix are you using? What is the alkalinity (carbonate hardness)in it?

What are you using to replace evaporated water? Tap water?

Is there any artificial rock?

The problem is easy to solve, as long as you know the source of the alkalinity and can stop it.

What alkalinity kit (it may be a testing error).

What exactly did you add to boost calcium (some forms boost alkalinity as well).

 

[ChrissyRay]

What salt mix are you using? What is the alkalinity (carbonate hardness)in it?
-- Instant Ocean with 8dkH

What are you using to replace evaporated water? Tap water?
-- R/O Water with 96-98% Rejection Rate

Is there any artificial rock?
-- No artificial rock, only on 4lb live rock

What alkalinity kit (it may be a testing error).
-- Tested with three different types - Aquarium Pharmaceuticals, Tetra, and Sera

What exactly did you add to boost calcium (some forms boost alkalinity as well).
-- We are adding Seachem Liquid Calcium - "Reef Calcium"

I really hope that answers the questions thourghly. My husband and I really appreciate all your help!

 

[Randy Holmes-Farley]

I would stop using the Seachem calcium. I have discussed this with them several times, and seem to get nowhere.

The polygluconate has several issues, one of which is it may be detected in an alkalinity kit. The second is that it may accumulate in the water, and the third is that if it is completely biodegraded, then it is adding alkalinity to the water, just as calcium acetate is a complete calcium and alkalinity additive system.

Here's an example of one such discussion with Seachem:

http://reefcentral.com/forums/showthread.php?s=&threadid=616674

 

[ChrissyRay]

Is there a calicum suplement that you would recommend?

 

[Randy Holmes-Farley]

I prefer balanced calcium and alkalinity additive systems (limewater, two part systems, CaCO3/CO2 reactors, etc.), but as a pure calcium supplement, you can use ESV, Kent, Dowflake from Home Depot, or if you like Seachem products, Seachem Reef Advantage Calcium or Reef Complete.

Here's a DIY two part system recipe:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php


and this article may help:

How to Select a Calcium and Alkalinity Supplementation Scheme
http://www.advancedaquarist.com/issues/feb2003/chem.htm