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Sv: Aquatic Plants Digest V3 #727, "hardness and plants"

Hello everybody and Merry Christmas.

+AD4-From: Dave Gomberg +ADw-gomberg+AEA-wcf.com+AD4-
+AD4-Subject: Hardness and plants
+AD4-A couple of remarks have appeared on this list lately that I fear may be
+AD4-confusing to tyros.  Some folks have intimated that +ACI-hardness+ACI- is bad for
+AD4-plants.  First, I am not an authority on this subject so I used the Tropica
+AD4-catalog as a reference.  Second, European water is ofter VERY HARD, so when
+AD4-Europeans say hard they mean something like OK or West Texas.  Where a
+AD4-teapot lasts a week before it fills up with CaCO3 deposits.  These remarks
+AD4-also apply to those who are concerned about using a substrate containing
+AD4-shell fragments for planted tanks.  I will not address the needs of fish
+AD4-here.  Some fish DO require soft water.

In Denmark very hard water is usually considered water with a TH (+AD0-GH)+AD4-20 DH. I have +AH4-22 DH, some have
+AD4-That said, hardness is a blessing.

Soft water is a blessing, explanation follows later

   Hardness comes in two kinds, permanent
+AD4-and temporary.  Chemists, forgive me, I know this is obsolete terminology.
+AD4- But I am trying to deal with whatever folks may conceive hardness to be.   
+AD4-Permanent hardness is ordinarily a sign of calcium in the water (sometimes
+AD4-Magnesium).   Both of these are essential plant nutrients and used in
+AD4-significant quantities.  Calcium and sulfur are sometimes called the +ACI-other
+AD4-Temporary hardness is permanent hardness plus transient hardness.
+AD4-Transient hardness is often due to CO2, another serious nutritional
+AD4-requirement of plants.  It is not necessarily bad.

+ACI-soft +ACI- water does not sort out any of these nutrients, we are not talking +ACI-destilled+ACI- water.

Your explanation, allthough maybe not wrong, might confuse one or another, I think, so let me try it +ACI-my way+ACI-:

The traditional +ACI-hardness+ACI-, be it TH or GH ( G for gesamt (+AD0-total in german)) is a measure of the kations
Ca+-+- and Mg+-+-. Nothing else, although I don+ALQ-t know if there is a test kit out there that measures differently.

The TH/GH or the old fashioned soaphardness does not tell anyting about what anions are following the measured kations. And anions are always following.
For this purpose we have the KH, that measures the amount of carbonate and bicarbonate, thus telling (roughly) how many of the kations come connected with carbonate/bicarbonate and how many come connected with other anions( like sulfate or cloride among others). The KH is IMO not a hardness-measure. It is more a measure of alkalinity ( alkality?). And alkalinity is of prime importance for the pH as pH, CO2 and alkalinity are interactively connected. For futher explanation see thekrib, Nestor 10 or Steve Pushak .

Many places in Europe the KH is about 1/2 to 3/4 of the TH

+AD4-Going thru the Tropica catalog, I found only two plants that will not
+AD4-tolerate what Tropica calls +ACI-average+ACI- hardness (which is about 150-200ppm
+AD4-in most of Europe, I would guess).  They are the rare Eusteralis stellata
+AD4-and our old +ACI-buddy+ACI- Glossostigma elantoides.  And there are folks who will
+AD4-tell you Glosso requires hard water.   So go figure.

With all due respect for Tropica, it is an amazing compagny producing a great variety of high quality  plants.
Some plants needs acid water to grow.
Some needs alkalic water to grow.
But most plants can grow under different condition while having preferrence for one specific condition.
In most cases it is not a question of either - or, but a question of a gradual transition. Was it not so, our planted tanks with many different plants
would not be possible.

One of the reasons for confusion in this area is IMHO the uncritical use of the expression +ACI-hardness+ACI-, sometimes used for TH, sometimes for KH. To describe reasonably well a waters quality you need both
measures (KH and TH). An example from the extremes might explain: At some places, but not many, the majority of minerals in the water are from common soda (Na2CO3). The TH in such a water is very low, but the
KH very high. And that is soft water but unsuitable for most purposes other than washing +ACE-

In many cases it brings more sense to talk of a waters pH than of its +ACI-hardness+ACI-, but of course the more relevant parameters mentioned, the better is the describtion.

Back to the +ACI-soft water is a blessing+ACI-
A good compromise (for many reasons) - and we have to compromise all the time when dealing with many different plants and fish from tropical rainforests -  is neutral to slightly acid water. And neutral or slightly
acid water is not possible ( with a safe for the fish amount of CO2) unless the KH is low. See the charts of CO2/KH/pH at one of the before mentioned sites.
In this scenario i consider TH of little importance. 
With water like that I have (TH+AH4-22, KH+AH4-14) it is a nuisance to make it suitable, but it certainly is worth the trouble: Pencilfish breeding in a community tank, no algae problems and most plants growing well ( C. crispatula-type being an exception, is a good example of the +ACI-not either- or+ACI-. It prefers alkaline water, but grows in acid.)
So to me soft water would be a blessing. If Rif Vally cichlids or livebeares were my interest, my type of water would be a blessing. This, I guess, answers your last message: 
+AD4-Please don't spend a lot of money, time and energy fooling around with your
+AD4-water unless you KNOW you need it.  It is more likely to cause harm than good.

Cheers Ole