Water Hardness? How do you mean?

[Watcher74]

Ok, I need a lesson here.

I understand that Carbonate Hardness (KH) is a measure of carbonate and bicarbonate ion concentrations and is a measure of the buffering capacity of your water.

I also understand the General Hardness (GH) is a measure of magnesium and calcium ion concentrations in your water.

But here's the thing...

My tap water shows 17 dKH of Carbonate Hardness...

but only 3 dGH of General Hardness.

And I'm being wishful with that high of a reading of the GH. There is hardly any coloration at all on that test.

So do I have hard water? (KH?)

Or soft water? (GH?)

And what implications do these readings have for an aquarium and/or planted aquaria?

BTW: Ph of 8.5

 

[RTR]

You have both, one for each scale. Your Ca/Mg levels are fairly low = soft, your alkalinity is high = hard. The water is very highly buffered, but dandy for laundry and dishwashing.

Do you by chance have a salt-exchange softener operating? It is not required to have highly variant hardness readings on the two different scales, but it is the most common case on the boards. The tests are scaled using CaCO3 as the standard, but that says nothing about whether the hardness is all Ca++, or Mg++, or less often a few others at low levels, but generally a combo principally of the first two. Alkalinity is generally an equilibrium of HCO3- and CO3--, but it too can include others such as phosphate - but those tend to be very low in unpolluted natural waters (and are used in some water processing).

 

[Watcher74]

Salt-exchange softener?

By this do you mean at the local water company?

I found the local water report at:

http://www.cstx.gov/docs/water_quality_report.pdf

at the bottom right of page 4 it shows:

Alkalinity (Bicarbonate) 366
Alkalinity (Carbonate) 11
Alkalinity (Phenolphthalein) 5
Alkalinity (Total) 377
Calcium 2.96
Chloride 56.8 250 ppm
Dissolved Solids 541 1,000 ppm
Fluoride 0.36 2.0 ppm
Magnesium 0.65
pH 8.46 6.5 - 8.5
Sodium 200
Specific Conductance 891 mhos/cm
Sulfate 6.78 250 ppm
Total Hardness (as CaCO3) 8.14
Turbidity (2003 results) 0 - 0.44 NTU

I'm not sure if this is of any help. But if I was concerned as far as aquatic plants, would hard water plants be more at home in my local water?

Or would soft water plants?

Man, I wish I could go back to school and aquire about 3 more areas of knowledge for all this.

I appreciate your help on this RTR. Or anyone else that might know how to tell me more about this. Or where I can find the applicable information maybe?

 

[RTR]

The almost complete selection of aquatic plants prefer hard water over very soft water - I think that Tom Barr lists 3 or 4 plants which do not do well in other than soft water, and only a collector of plants would demand that. The plants commonly used in tanks will do fine in most tap water.

When breeders (and most books) speak of hard water, they are talking about the Ca/Mg hardness, as those ions are the ones affecting egg membranes adversely in blackwater fish. Yours is soft there, but you do have a decent proportioning between Ca and Mg, so should be fine with regular routine changes which should cover the replenishing of those ions just fine.

Your KH/alkalinity is high/hard, no question. If you go for compressed CO2, it will take some push to get much pH reduction and much CO2 dissolved. I like and use the chart on the San Franciso groups's site:

http://www.sfbaaps.com/reference/table_01.shtml

If you go without CO2 gas supplement and use lower light, little mineral supplement, you should not have any issues. I'm sure that you already know that your pH is stable as a rock.

If you want to browse for more detailed plant info, especially for the DIY types (not me, I am too lazy- I am low/moderate light, some supplements - but all those straight from the shelf, mainly Seachem's stuff), a good start is available on Chuck Glad's site:

http://www.csd.net/~cgadd/aqua/

And for commercial stuff, Seachem's site:

www.seachem.com/

The Krib is a universal source for info, but can be confusing as it presents all viewpoints in many voices:

www.thekrib.com/

HTH