# is hardwater a good thing?



## Kurt Reinhart (Mar 4, 2003)

I wasn't really sure where to put this posted but thought that a lot of people in this section use a range of techniques (high, medium, and low tech) for their tanks.

I've ordered a used copy of Diana Walsted's book. So maybe this is all covered in her book... If so shame on me for being impatient. Anyway, I noticed that many recommend adding oyster shells to the soil media if doing a low tech tank. However, many books and posts seem to frown upon adding shells, limestone rock, etc. and seem to try avoid hard water. I think this is because it interferes with CO2 levels in the tank and makes it hard for plants to acquire nutrients.

Here is a picture from a Florida spring (this is also posted under local biotopes- "Florida Spring").









I've been amazed at how well the plants grow in these springs and how the conditions seem to contradict many aquarium practices. For example, I came across a dissertation describing the water chemistry of Florida springs they are described as-

"As a group, Florida springs exhibit a wide range of water chemistries. However, the springs, in general, can be characterized as alkaline (pH averaging 7.4) and chemically rich (specific conductance averaging 713 μS/cm @ 25 C). Total alkalinity and total hardness values average 137 and 244 mg/L as CaCO3, respectively; thus the springs are considered to be hardwater. The waters are also nutrient-rich with total phosphorus concentration averaging 0.054 mg/L and total nitrogen concentration averaging 1.6 mg/L."
http://etd.fcla.edu/UF/UFE0008963/strong_w.pdf

I'm pretty sure that 1 mg/L =1 ppm.

So 244ppm of CaCO3 is pretty high by most people's standards. I don't think that the nitrates or phosphorus are high relative to levels recommended for a planted tank (P=0.05ppm, nitrates=1.6ppm). High CaCO3 is supposed to make it difficult for plants to acquire nutrients and CO2 (right?- I'm a newbie so may be completely off). Anyway, these plants are growing incredibly well IMO. I've read that some plants can use CaCO3 as a source of carbon. Is there a hidden value to this type of water?

So I'm wondering if having high CaCO3 levels in a tank planted with plants adapted/acclimated to utilize CaCO3 might negate needing CO2 supplements (not that you're all using them especially in this section). Are people avoiding high CaCO3 because many plants are not able to use it as a carbon source?

I'm considering designing a FL Spring biotope tank and am interested in the pros and cons of high CaCO3 levels in a tank. It seems if you use the right plants that things can go well. Maybe I'm way off base though. Please enlighten.


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## mistergreen (Mar 3, 2007)

wow, that's a pretty picture.. If somebody can ID those plants, it would be cool.

It depends on the plants if it can flourish in hard conditions but if you're going to mimic this biotope, you'll be fine.


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## Kurt Reinhart (Mar 4, 2003)

Here is a link with more discussion on the springs and photos.
http://www.aquaticplantcentral.com/forumapc/local-biotopes/46508-florida-spring-biotope.html

I did not take the picture. Based on the photographer's expertise and my own, I think the plants are as follows:

(from right to left)
chara, red ludwigia, and either Sagittaria kurziana or Vallisneria americana

Both the Sag and Val often dominate these springs. Most springs that I've researched on the internet report Sag. kurziana being dominant. I'm not really familiar with chara. It is listed as inhabitating several springs. If you look carefully there is actually a lot of it to the left as well as the right. It looks weedy. It is technically not a vascular plant (its macroalgae according to http://naturalaquariums.com/plantedtank/0508.html) and may compete well with algae...


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## mistergreen (Mar 3, 2007)

you should be fine then... All these plants love hard water..
chara is an algae.
http://www.aquaticbiologists.com/aquatic_plants.html
I guess you can use dwarf hairgrass in chara's place.

If you can mimic those rolling slopes that would be awesome.


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## Kurt Reinhart (Mar 4, 2003)

Thanks for the link. The person that shared the picture thought that it was chara in the foreground. I'm not really sure though. It looks too linear (i.e. grasslike) and dark green. All the chara photos that I've seen make it look more yellowish and its segmented along its stems (sort of like the Milfoil picturs on your link). 

I keep hoping that someone will see it and immediately have a better idea.


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