[Wet Thumb Forum]-using Calcium & Magnesium from coral chips

[juggler]

Currently I am using a small amount of coral chips in my filter as a source of Ca and Mg and kH buffer. (kH about 5, gH about 12~20). I have got some questions:
1) How low a gH would be a rough guide that the tank has enough Ca so as not to cause an overdose?
2) Roughly, how high an amount of Ca would cause toxicity?
3) Is the amount of Mg in corals sufficient or do I need to dose extra Mg?
4) If a high level of K (20~30ppm) inhibits Ca and Mg, would a higher level of Ca and Mg balance this equation?

Thanks.

[juggler]

Currently I am using a small amount of coral chips in my filter as a source of Ca and Mg and kH buffer. (kH about 5, gH about 12~20). I have got some questions:
1) How low a gH would be a rough guide that the tank has enough Ca so as not to cause an overdose?
2) Roughly, how high an amount of Ca would cause toxicity?
3) Is the amount of Mg in corals sufficient or do I need to dose extra Mg?
4) If a high level of K (20~30ppm) inhibits Ca and Mg, would a higher level of Ca and Mg balance this equation?

Thanks.

[JamesHoftiezer]

Welcome to the forums.

Someone else will have to give definative answers but I beleive with where you gH is compared to your kH, you do not want to dose additional Mg. I don't think you're in any toxic range, but it may complicate your fertilizer regiment by limiting uptakes.

James Hoftiezer

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[Roger Miller]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>1) How low a gH would be a rough guide that the tank has enough Ca so as not to cause an overdose?
2) Roughly, how high an amount of Ca would cause toxicity?<HR></BLOCKQUOTE>I'm not exactly sure I understand your questions, so my answers may be nonsense.

I've never heard of a calcium level that would be considered toxic. Plants can grow quite well with at pretty high calcium concentrations. Most sources seem to agree that there are some plants that grow better in soft water than they do in hard water, but in reading Kasselmann it sounds like the difference is made by KH, not by GH.

At the low end, I've talked to some people can grow plants well with 1 dGH. But some plants seem to stay small under those conditions, and the tanks are prone to problems. 2-3 dGH seems to be about the minimum that people use without a lot of problems.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>3) Is the amount of Mg in corals sufficient or do I need to dose extra Mg?<HR></BLOCKQUOTE>
It may be enough. If your doing it that way and it works, then it must be OK. If you need additional magnesium then you might try using crushed dolomite or dolomite chips in the place of the coral. Pure dolomite provides Ca and Mg in a ratio of 1.7:1 Ca:Mg. The ratio may be higher for common products.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>4) If a high level of K (20~30ppm) inhibits Ca and Mg, would a higher level of Ca and Mg balance this equation?<HR></BLOCKQUOTE>It can. You can also dose the calcium and magnesium to the roots of some plants instead of dosing to the water. Just add calcium carbonate tablets, dolomite or limestone chips to the substrate under the plant. You might be better off reducing the K level rather than increasing Mg and Ca.


Roger Miller

[IUnknown]

Another K limiting topic. I wonder if anyone has run tests on this subject. It would be good to post a good article on the subject.