# How important is a low pH?



## HeyPK (Jan 23, 2004)

Just because many soft water crypts live in soils where the pH gets down to 4, does that mean that they can't be grown or grow poorly if the pH is higher than 4? Is there actual evidence to show that good growth is dependent on a very low pH and not on something else that is not dependent on low pH? 

The table, below, shows nutrient availability in soil over a wide range of pH.


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## DelawareJim (Nov 15, 2005)

The chart shows why horticulturalists always recommended a pH of 6.5 - 7.0 for growing most plants. It's the range in which the most number of nutrients are readily available to the widest range of plants.

Plants generally, are adapted to the environmental conditions where they have the least competition from similar species. Lower pH growing species have a greater tolerance to growing in more adverse conditions and often have a lower need for certain chemicals that generally raise pH like calcium or magnesium. One effect of raising pH is that copper, iron, manganese, nickel, and zinc become less available to plants. If Crypts have a high need for these chemicals some stunting may occur. Also phosphorus changes from H2PO4- to HPO4-- as pH increases from about 5.5 to 7.5 altering availability to plants.

In short, they may or may not grow poorly in higher pH conditions depending on whether the chemicals that raise pH generally have toxic effects when concentrations reach high levels or if the change alters a chemical to an unavailable form. The only way of really knowing is to try growing some in higher pH conditions and studying the effects.

Cheers.
Jim


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## HeyPK (Jan 23, 2004)

That's exactly what I think needs to be done---try growing some of the species that come from low pH environments in near neutral environments that still consist of a semi-decayed leaf substrate.


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## SCMurphy (Jan 28, 2004)

I can't seem to write this in a way that doesn't sound sarcastic to me, I apologize. The European guys have tried growing the crypts in higher pH soils/substrates and found that they need the low pH. They have written about it in AquaPlanta the German aquarium plant publication. My German is non-existent and I don’t have the back issues other than a couple Jan gave me so I can’t hand you the papers, the important ones are probably translated on Jan’s site. Anyhow, what I’m hoping is possible is ‘weaning’ them off the need for an acid environment. If they are freshly collected there is no chance of moving them right to a neutral environment, they have evolved past ‘tolerant’ to ‘obligate’.


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## dennis (Mar 1, 2004)

Chris's substrate is near neutral, if I remember correctly, and that is with "proper" testing. I believe he is growing some of the acid loving species in this substrate and obviously having good success. Let's not forget also that these uber low pH's (is that a word) would normally mean toxicity for many elements, especially Fe and Al. That is in a soil solution, not a soilless solution like we have. Using straight litter negates the Al issue and also the Fe issue to some extent. I wonder if the Al toxicity aspect is the reason that Jacobsen seems to imply in his litter paper that the best success was with straight litter that had no mineralized soil mixed in.

If crypts adapt anything like many terrestrial "houseplants" then it should be possible to condition successive generations to handle different conditions.


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## HeyPK (Jan 23, 2004)

What is needed is a controlled experiment that shows that it is the pH that is necessary for good growth, not some other factor. I looked over the articles on Jan's site and, as far as I can tell by the titles, the only one that discusses growth needs is Jacobsen's article on using beech leaf litter.


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## DelawareJim (Nov 15, 2005)

I think Dennis is right in that it will take generations to evolve some of the "uber-low pH" plants to a higher pH. Or as Dennis alludes to, it could be something as simple as some soil chemical binding process that a slurry bypasses.

And as PK (Paul is it?) points out, only controlled systematic testing would really quantify that. Hopefully that is something we are willing to determine.

Cheers.
Jim


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## HeyPK (Jan 23, 2004)

I wrote Jan an email to see what he thinks about this question. I don't know if I used the right email address. Last record I have of his sending emails to the Crypts mailinng list was that emails to and from him were going through Richard Sexton's site. (crypts at bart dot nl) But, that was back in 2004.


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## SCMurphy (Jan 28, 2004)

The point I'm trying to get across is that the ECS guys have already invented this wheel, systematically, repetitively, in several languages. They have collected data from the plant localities, they know what conditions the plants were living in, they have been successfully cultivating these plants for a while now, they have been collecting the cultivation data. That's why they have moved into the area of trying to find the best litter to get the conditions they want, based on the area that the plants were collected. They have systematically tested litters that varied in pH and found the blackwater crypts did the best in the lowest pH litters. So to answer the original question, yes there is actual evidence.

If you used crypts at bart.nl then he'll get it.


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## EDGE (Feb 28, 2004)

There was a post with an article by Jacobsen a while ago. low pH isn't the major reason for success with blackwater crypts. acids such as humic, fulvic, amino, and etc that causes the low pH is the important element. Humus to simplify things.

If low pH was the case, than anyone can use phosphoric acid to bring pH down to 3.


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## Xema (Mar 24, 2004)

I use to used ortophosphoric acid to drop pH value, 50% diluted, 1 or 2 drops every week, that is keep my pH around 3,8/4,00... I have a mesh bag with beech, pine leaves and peat sumerged into the water.


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## blacksmith37 (Oct 10, 2006)

I would say low pH is not required , as long as you are in a reasonable range like 6 to 7.5. 
The bulk solubilities of various ions vs pH. is not very important. Because the root hairs produce enzymes (and ?) that will complex with the elements the plant wants ; and make them soluble as a complex. I remember PHDs in chem and p.chem noting in internal reports, they were suprised how effective this enzyme action was; bulk pH was not a factor. Admittedly this was work with corn and soybeans, but a crypt should be as smart as corn and beans.


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