KH/GH unit of measure questions

SnakeIce

SnakeIce

AC Members
May 4, 2002
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North Ga, USA
Real Name
Frederick
my hagen carbonate and general hardness tests have value ranges of the results of the tests.

For GH those numbers are 0-60 soft, 61-100 slightly hard, 101-200 moderately hard and over 200 as very hard. something in there about mg/L CaCO3

KH ranges by the tests are as follows <20 suggested to adjust with buffer, 20-80 is range that is low ph or neutral, >80 high ph and salt water to be between 105-125 and fiddle with buffer if needed. these are mg/L

I was just looking at the charts for CO2 and those are listed in degrees of hardness.

I don't know how the numbers the tests give are related to degrees and if you could explain or point me to the conversion table I would apreciate it.

my 20's tank values are currently at ph 7.4, kh 30, gh 40, nitrate 5 mg/L, Phosphate 1 mg/L, no test for K and no co2 injection. I just started testing on that which I have tests for and have dosed phosphate as that was at 0.

hagens 'master test kit' doesn't have the test for K levels. where would I find one and what brands do you use?

we have had such wild swings in water values here I am not sure what to do with water this soft or know if I need to do anything.
 
This should help...
http://www.thekrib.com/Plants/CO2/hardness-larryfrank.html

It seems your water is on the soft side but the more important "worry factor" is the wild swings. If you were to do a large water change, you would want to test the tank and tap water to be sure they aren't too different.
I don't think anyone tests for K. The general guidline is dose 20ppm per week and do 50% water changes per week.
 
well the wild swings are predictable in that they are related to the weather and season. the water systems source is a watershed and during the dry summer months the ph goes up abit although that tends to be a gradual thing. the wild swings I was refering to was the water system I just left which used well water part of the year. the aquifer water has a steady ph of about 8 and is very hard, although during the dry summer my first year here the ph hit 9.5 out of the wells.

the watershed is alot more stable only rangeing from 7.2-7.8 over the course of the year.

I've just never had water this soft befor and wanted to post my values to see if anyone saw a potential problem.

would I need to up the kh from the values I listed if I were to start CO2?
 
beviking said:
This should help...
http://www.thekrib.com/Plants/CO2/hardness-larryfrank.html

I don't think anyone tests for K. The general guidline is dose 20ppm per week and do 50% water changes per week.
Click to expand...

thanks for the link, thekrib is an awesome site but I forget about it as I find the archives abit dry and static unless its something I want to know.

are there just no tests available for K? or is it really not that important to test for....
 
LaMotte or Hach has one, LaMotte I believe, but it is $$$ and not paricularly useful. Your utility may have a figure for the average value. Beyond that, the sort of process beviking suggests is what most of us do.
 
You have a kH of 1.7°H. This is too low for safe injection of CO2. It must be brought up to 3.0 - 3.5°H to avoid a possible crash.
Baking Soda will raise kH. MgSO4 will raise gH. I dose 1/2 tsp. MgSO4 as a matter of course in my 10 gal. and 2 tsps. in my 40 and 55s. Your 20 would fall somewhere in the middle. MgSO4 doing is not critical so there's a bit of margin for error there. Bicarbonate of Soda can be a bit more touchy so you need to start low and see what it gives you. You will see an almost immediate increase in gH.
For water is as soft as yours, you can use crushed coral in a filter bag and placed in your filter, although the affect of this will take at least a week to be realized. I would use Baking Soda initially, in conjunction with the coral and eventually the Baking Soda should not be necessary.
I have been using Tetra Test for both gH and kH, with a degree of confidence. I have little confidence in 'hobby level' test kits, but instead use them as reference(did it go up or down).
For K, I don't even trust Hach or LaMotte, especially for the money they charge.

Len
 
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djlen said:
You have a kH of 1.7°H.
Len
Click to expand...

I'm a little confused as to how you got that number out of the kh 30 I posted having.

I confused the initial statment about gh(By definition, 1dGH = 10 mg/liter CaO) with what I am asking. I see the direction the equations go to get to degrees of carbonate hardness from gh, knowing some things I don't know about what I tested, but still don't understand how to come up with the number myself based on the 'kh' numbers my test give.

hopefully that wasn't to confuseing, its hard to make sence when you don't know what you are talking about.

I view chemistry as an awefull way to hide a little math, if I can see the math I might understand it but the work to do so makes it less than entertaining.
 
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I don't mess with math or equations. I simply typed the 30ppm into Chuck's calculator and the corresponding °H was 1.7°H.
Wasn't that one of the questions you requested an answer for?

Len
 
oh ok, but that was 30 mg/L not ppm. I should have stated that was the unit of measure when I posted the values.

I'll take a look and see how his calculator is set up as to the units of measure. that could be why I was a wee bit confused lol

I may be able to play with it and figure out the equation behind the scenes.
 
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