解决珊瑚缸里钙浓度和硬度两者问题的技巧

(文章引至"养鱼爱好者先驱"网站,本站beam翻译,因个人外语能力有限,如有错误请指点。)

对于很多珊瑚养殖者来说，在维护一个珊瑚缸运行时常会出现不理想的钙浓度和硬度数值，如何很好地解决这两方面可说是最令人烦恼的化学问题。众多珊瑚养殖者都知道，如果这些起限制作用的因素不维持在合适的数值范围，珊瑚和其他生物将很难构建它们的碳酸钙骨架。要知道如何去解决如此问题，事实上是有些难明白的。也正如，对已消耗的东西不是靠添加更多的量这种简单方式就能解决的。

本人在提升钙浓度到200 ppm以上时碰到了些问题。我已经使用石灰(CaO)两星期了，是石灰上面的水溶液，约每天添加3/4加仑。但钙浓度从未能高于 250 ppm并会自各下降回200 ppm以下。后来我又买了些 Turbo Calcium（加速补钙的产品），并按照产品的建议使用标准添加但仍未真正的成功。之前我未曾使用过Turbo Calcium这类产品，并在担心使用此产品多少量内才会安全。我现仅有2个菇类和2个雀鲷类生物。有什么建议？

不好的是在珊瑚缸里，钙浓度和硬度在很多方面都相互牵连着,这些关系如没能得到全面的认知将会导致严重的问题发生。假如你添加过量的钙补充物，将降低水体的硬度，并在缸里形成碳酸钙沉淀物。同样的，添加太多的硬度补充剂也会造成钙浓度的降低。所以当尝试去解决一方面问题时常会导致另一方面问题的出现。甚至如果你采用了错误类型的添加物去改正钙浓度或硬度的问题，你或许完全不能实现什么结果并在鱼缸里制造了些石灰石出来。

本文章将阐明在典型珊瑚缸里遇到的钙浓度和硬度问题的各种类型, 也将详细描述如何去解决这些问题。通过阅读本文章，或许你会感觉我在将问题过度复杂化。然而请记住本文章描述的是如何去解决各种不同情况下的问题，当遇到的任何一个珊瑚缸将会与所描述的其中之一相符合，所以都会有一小章节适合。

不像我写的其他文章那样，本文章不是要去深入了解珊瑚缸里钙浓度和硬度的科学理论。那些理论已在我之前的几篇文章里有所论及。本文章阅读起来更像一门诀窍。然而，对用以修正钙浓度和硬度的化学添加物方面给予大家建议时，我已亲身经历过这些方法（在我的鱼缸上），并实在没有任何捷径可确保成功（但大量使用定会造成失败）。

在文章的尾部，我将会强调能避免这些问题的最好方法：使用钙浓度和硬度两者平衡的添加剂。我确信使用这样的添加剂将会消除大家在钙浓度和硬度方面遇到的大多数问题，和我非常强烈推荐大家使用。

许多朋友都从水族测试剂上获得错误的读数。这些问题当中有些是测试剂的错误，有些是使用者的错误。无论如何，如果一个水族者去“更正”一个因测量错误的问题时，鱼缸或许从很好变成灾难性的。所以请注意，在对水体化学物做出任何大变动时，要使用不同的测试剂确定读数，最好使用不同牌子。在以下情况更应该特别注意，就是当你往珊瑚缸里加入添加物后，测试结果似乎没有按相应方向变化的。

在进入分析问题和方法前，让我们先定义下什么情况是属于要解决的问题而什么情况下不是。基于涉及珊瑚和其他生物体钙化的出版刊物，我推荐以下数值情况：

硬度(这里说的硬度取决于碳酸氢盐和碳酸盐，但不含括硼酸盐，所以那些使用Seachem牌子海盐的必须大幅提高这数值已包含被计入硬度测试里的硼酸盐)。

如果那些参数都在这些数值范围内,那就不必对珊瑚缸的化学方面做任何的更正, 即使是为其他原因而选择这些更正。从这意义上来讲，这两个参数互相对应的实际数值是多少，只要都在这范围内都是一样的。例如硬度数值在4meq/L，对于钙浓度是在380 ppm 好还是在 450 ppm好是没有固定的。给人感觉是有点随意性，特别是数值处在高值界限时。事实上，出现数值达到最高界限的首要原因是，当一个参数数值已经高于最高值时，而另一参数却较低须维持它在最小值以上，这常常都会很困难的。所以如果一个参数轻微高于最高值而另一个参数值很好时，这种情况是不需要担心的。

如果你的珊瑚缸的某个或全部测量结果都在要求范围外时，究竟如何去更正他们的确要取决于这两者之间的关系。对很多水族爱好者来说，在维护钙浓度和硬度这方面也常常会容易出现问题。

图1 展示了在珊瑚缸里钙浓度和硬度的图形。在中间位置的红色区域代表了两个参数的期望数值。蓝色点代表了当前天然海水的数值。我们将会使用本图去确定对处在红色范围外的四个被标有数值的区域的每一个改动方向。所以第一步是先看看你的珊瑚缸的数值是处在图形里的哪个地方，然后依照对应区域给出的改正方向。

对处在区域1的情况这是最容易修正的。不幸的是它也不是最常发生的问题。在这种情况下，钙浓度和硬度都高于天然数值。另外，如果你让鱼缸在此情况下独立运行不再加任何东西，这个问题几乎会自己完全解决，参数会降回到正确的红色区域里（同样如果你这时间再等长些，它也将会降到问题区域2里去）。

这区域表明的现象是钙浓度和硬度都被提升过高，对这种情况通过从水体中移出部分碳酸钙成分，同样可通过生物吸收形成珊瑚的骨胳或钙藻，或通过物质沉淀，如在加热棒上，经过上面的各种方法钙浓度和硬度将会降至合适的浓度值。更确切的说，珊瑚缸的这些参数是沿着与本区域两条边缘线平行的直线方向移动，并会直接进入红色目标区域（例图2中蓝色箭头）。如果你的珊瑚缸恰好在这两条边缘线中间，可看例图2，那么参数会继续沿着这两条边缘线的中间值来移动并下降至目标区域。

可看出这种移动方向如继续下去将会离开目标区域的最底线（进入区域2），当然，当珊瑚缸的参数降至目标区域内时，你会不得不重新考虑加入正常的钙和硬度添加物。

处在区域2的情况同样是一个很容易更正的问题，并且非常普遍。在这案例里，钙浓度和硬度都低于正常值。如果你有任一个参数均在红色目标区域的珊瑚缸，让珊瑚和钙藻（例如钙化）生长，同样也会进入区域2。正如前面（例图2），向下移动方式是平行于区域的两条边缘线。为何会普遍存在这个问题的原因是：任何没有添加足够钙和硬度去平衡珊瑚缸的需要几乎都会踏入这区域。

要更正这种情况并回到红色目标区域，有人想到是用一种平衡方式添加钙和硬度。有幸的是，实现这种平衡有很多方法，例如使用石灰水（kalkwasser），碳酸钙/二氧化碳反应器，和许多已经平衡了钙浓度和硬度的添加物（例如B-ionic，C-Balance等等）。这些产品您加的越多，更正的步伐就更往前一步（例图3中蓝色箭头）。当然，过量添加将会再次进入问题区域1中，但是真的这种情况出现了，那么您可停下来不加任何东西然后观察等待它自各降回到目标区域里。在文章的最后我将会再讨论这平衡添加物。

当然,您可以添加缺乏平衡关系的钙离子和硬度（也就是彼此之间在特定浓度方面没有任何关联）。例如，添加氯化钙和碳酸氢钠也能工作很好，但是您必须对每样要添加的数量做出精准的调整。因此，您假使使用的是这种添加方式,那么对钙浓度和硬度水平的观测就要更加细心。

请记住一点就是产品的建议用量是针对维持珊瑚缸正常消耗方面，而不是进行本质性的纠正用量。在进行上述纠正时，您添加的份量必须比建议的还要多。如果您所添加的是一个平衡添加剂（PH值不会超出7.9至8.5范围），那么最坏的情况莫过于是过量添加（甚至极度过量）而导致浪费一些金钱及在您的加热棒和珊瑚缸的某些部位上出现额外的碳酸钙沉淀。在本文章的末尾将更多地讲述到这些平衡添加剂。

另一方面，如果使用独立的钙和硬度添加剂，您就必须非常小心避免其中一个相对另一个添加过多而出现不平衡情况。为了确定这些添加物究竟低了多少，您将依赖比建议次数还要多的日常测试来决定添加多少这些添加物进珊瑚缸里。

最后，如果您已经添加了大量的钙和硬度添加物，但是仍不能维持在所希望的数值内，您也许要测量下水体中镁离子的浓度水平。镁离子对阻止形成碳酸钙沉淀上扮演着重要角色，如果镁离子被大量消耗并延迟下去的话，钙离子浓度和硬度将以极其快的速度降下来。在我看来，镁离子浓度出现问题的频率要远远高于其正常情况，但好在于很容易使用测试剂测量和必要情况下很容易进行补充，此问题发生时一定不能置之不理。本人建议镁离子维持在天然海水里的浓度水平约1300ppm。

对区域3的更正方法

Zone 3 problems are a little harder to correct, and are fairly common. It is, in fact, the problem in the real question posed at the beginning of this article (it doesn’t say so there, but the alkalinity was 3.2 meq/L). This problem is typically caused by overdosing alkalinity RELATIVE to calcium, but does not necessarily imply that calcium is either too high or too low (though it is almost always too low). To correct problems in this zone, monitoring of calcium and alkalinity values during correction is especially important.

One more word about this zone before getting to solutions: Many tanks end up here because aquarists are trying to correct pH problems by adding “buffer.” In my opinion, one should not try to correct any pH problem by simply adding an alkalinity supplement. If you are low on alkalinity, it is a fine course of action to raise the alkalinity. But if alkalinity is OK, or even high, adding an alkalinity supplement to alter the pH may simply create a worse problem. Better solutions to pH problems are discussed in this recent article⁶.

If this problem is extreme (i.e., you are far from the line at the right hand edge of zone 3), then water changes may be the best way to correct to the problem. In most cases, however, water changes aren’t necessary.

I would advise correcting this problem by adding a calcium chloride supplement until you have moved into the target zone (or zones 1 or 2 that you can then treat as described above) as shown in Figure 4. Almost any brand of calcium chloride will do (Kent Turbo Calcium, Kent Liquid Calcium, ESV, etc.). Certain other calcium supplements may also be OK (such as just the calcium component of the two-part calcium and alkalinity additive systems), but you do not want to add any alkalinity. You CANNOT use limewater or a calcium carbonate/carbon dioxide reactor to correct this problem. Any of the balanced calcium and alkalinity additive systems will move you parallel to the line at the edge of the zone, while you want to move over to it, and cross it.

If calcium is less than 400 ppm, I’d suggest using this handy online calculator⁷ to determine how much dry calcium chloride is necessary to move back to the target zone. Note that it is a minimum estimate because it does not know how much alkalinity you have, so it cannot know if you are only raising calcium directly (which it calculates) or are also precipitating calcium carbonate (when alkalinity is high this will probably happen, but is typically not a problem other than that it uses up some of what you add).

If the calcium is above 400 ppm in this zone (unlikely, but it does happen), then you can safely either do nothing until it drops and you need to add more calcium, and treat it as suggested in the previous paragraph, or you can add some calcium immediately, move into zone 1, and then just let it drop on its own.

Zone 4 problems are also a little harder to correct. It is typically caused by overdosing calcium RELATIVE to alkalinity, but does not necessarily imply that alkalinity is either to high or too low (though it is almost always too low). To correct problems in this zone, monitoring of calcium and alkalinity values during correction is especially important.

If this problem is extreme (i.e., you are far from the line at the left hand edge of zone 4), then water changes may be the best way to correct to the problem. In most cases, however, water changes aren’t necessary.

If alkalinity were less than 4 meq/L (11 dKH; the most common situation in zone 4; shown in Figure 5), I would advise correcting this problem by adding an alkalinity supplement until you have moved into the target zone (or zone 1). For systems with a pH of 8.2 or above, baking soda (sodium bicarbonate) is a good choice. For systems with a pH below 8.2, washing soda (sodium carbonate) is a good choice (though use some baking soda too if the correction is a large one and the pH gets too high; that is, above pH 8.5 or so).

To raise 50 gallons of tank water by 1 meq/L will require about 16 grams of baking soda (sodium bicarbonate; sodium hydrogencarbonate). Since a level teaspoon of baking soda weighs just under 6 grams, then 1 teaspoon will raise the alkalinity in that 50 gallons by ~0.4 meq/L (~1 dKH).

To raise 50 gallons of tank water by 1 meq/L will require 10 grams of washing soda (sodium carbonate). Since a level teaspoon of washing soda weighs just over 6 grams, then 1 teaspoon will raise the alkalinity in that 50 gallons by ~0.6 meq/L (~1.7 dKH).

One special note about washing soda: Apparently some Canadian brands of washing soda contain surfactants. VIP brand, in particular, contains them and a reef keeper using them on my advice turned his tank into a bubble bath. On questioning, the manufacturer did indicate that a surfactant is present. The same reef keeper says the local Arm & Hammer brand in Canada smells strongly of perfume. I’d avoid perfumed brands, if possible. My Arm & Hammer Super Washing Soda purchased in the US apparently contains no significant surfactants, and is not perfumed. Nevertheless, anyone using washing soda for the first time ought to put some in water and stir it around to see if soapy bubbles form. If so, I’d suggest finding another brand.

Many commercial alkalinity supplements will also be fine for this purpose, as long as no significant calcium is added. In general, I don’t prefer those that contain substantial borate. The alkalinity component of the two-part calcium and alkalinity additive systems would be OK. You CANNOT use limewater or a calcium carbonate/carbon dioxide reactor to correct this problem. Any of the balanced calcium and alkalinity additive systems will move you parallel to the line at the left edge of the zone, while you want to move over to it, and cross it.

If alkalinity is more than 4 meq/L (11 dKH; an uncommon situation), then you can safely either do nothing until it drops and you need to add more alkalinity, and treat it as suggested in the previous two paragraphs, or you can add some alkalinity immediately, move into zone 1, and then just let it drop on its own.

Just as in many other fields of human endeavor, the easiest way to solve reef tank chemistry problems is to prevent them from happening in the first place. That may sound trite, but there are ways to maintain reef tanks that require substantially fewer measurements of calcium and alkalinity than are required with other supplementation schemes. In fact, I haven’t measured either in my tank for over a year, and yet I expect that the levels are fine, just as they have always been whenever I have measured them. So while I am not saying that you should never measure things, I am saying that using appropriate methods may greatly cut down on the likelihood of having chemical problems, and thereby on the required frequency of measurement.

Calcium is largely consumed by formation of calcium carbonate. This happens biologically³ in corals, coralline algae, mollusks, and a variety of other organisms. It can also happen abiotically¹, such as by precipitation on heaters and pump impellers. In a reef tank with rapidly calcifying organisms, this effect will so predominate any other calcium export mechanism, that no others need be considered for this purpose.

Alkalinity² for our purposes here is comprised of bicarbonate and carbonate. The vast majority of alkalinity depletion in most tanks also comes about by the precipitation of calcium carbonate, as described above. In this process, as alkalinity is depleted by 1 meq/L, calcium will be depleted by 20 ppm. There are some other processes that can lead to alkalinity depletion, including partial cycling of nitrogen (from organic compounds to nitrate and no further) and the incorporation of magnesium into calcium carbonate, but these are generally much less important than calcification.

Consequently, alkalinity depletion in most tanks (especially in short time frames) is tightly coupled to calcium depletion, and if one supplements calcium and alkalinity in proportions equal to those that they are being removed, then it is MUCH less likely that calcium and alkalinity will become imbalanced⁴ and thereby trickier to correct. That is, the only problems that you will encounter are those in zones 1 and 2 (not enough or too much of these additives). Using a balanced scheme, you should not ever end up in zones 3 and 4, where you have substantial imbalances between calcium and alkalinity.

Additionally, overdosing of balanced additives typically seems to simply result in an increase in the amount of calcium carbonate that is being precipitated in the tank, and does not, in general, lead to substantial increases in dissolved calcium and alkalinity. This fortunate circumstance comes about largely because of the supersaturation of calcium carbonate¹ in reef tanks.

There are many ways to add calcium and alkalinity to reef tanks in ways that are balanced with output. These include limewater (kalkwasser)⁸ regardless of how it is dosed, calcium carbonate/carbon dioxide reactors, the two-part calcium and alkalinity additives (e.g., B-ionic, C-balance, Kent Tech CB, etc.), and a small selection of one-part additives, such as calcium acetate. I strongly recommend that you adopt on of these in your tank maintenance routine, and then never add any other calcium or alkalinity sources unless you are certain of what you need.

If you choose to add limewater, but find that using saturated limewater to replace all evaporated water does not quite keep up with calcification demand⁹, you can stretch the capacity of limewater by adding vinegar to the solution to enhance the solubility of the calcium hydroxide¹⁰.

I hope this article proves useful is understanding and dealing with the different types of calcium and alkalinity problems encountered by reef keepers. Once you get calcium and alkalinity under control, you are far along the road to having your tank chemistry optimal for its inhabitants. Once you accomplish that, then you can spend your time either enjoying your tank, or reading additional reef chemistry articles.