KH reference solution

CEReefer · Nov 5, 2020

Hi everyone! I need a Kh reference solution, GHL has one, but it always takes forever to get anything from them, let alone the 15$ of shipping they ask.. so.. Do you guys know how much kh is in those lab solutions that are either 500 or 1000 mg/ml CaCo3?

Randy Holmes-Farley · Nov 6, 2020

CEReefer said:
Hi everyone! I need a Kh reference solution, GHL has one, but it always takes forever to get anything from them, let alone the 15$ of shipping they ask.. so.. Do you guys know how much kh is in those lab solutions that are either 500 or 1000 mg/ml CaCo3?

I do not know what lab solution you are talking about. There are commercial standards, or you can make your own.

What to use, however, depends on your intent with it.

LOVEROCK · Nov 6, 2020

Randy Holmes-Farley said:
I do not know what lab solution you are talking about. There are commercial standards, or you can make your own.

What to use, however, depends on your intent with it.

randy , is it safe to put sample line of KH director into alk reference from GHL, and then back into the sump ? or does it contaminate the sumps water

Randy Holmes-Farley · Nov 6, 2020

LOVEROCK said:
randy , is it safe to put sample line of KH director into alk reference from GHL, and then back into the sump ? or does it contaminate the sumps water

Depends on what it is. Alkalinity reference solutions in general are obviously not intended to dose to an aquarium, but they may be coincidentally safe.

CEReefer · Nov 6, 2020

@Randy Holmes-Farley so.. GHL has a 7.5 KH reference solution, suggest to sample it 3 times with KHDirector, average the results and adjust the %variation difference (measured - reference) that the device spits out. Unfortunately it takes forever for them to ship once you place an order (4-7 business days depends on the weather... so I was trying to get one of these reference solutions (link below) and kind of diluting it to make my own..

"Alkalinity, CaCO3 500 mg/L Calibration Standard"

Storage: 2-8°C

www.thomassci.com

Randy Holmes-Farley · Nov 6, 2020

I cannot tell from the site you posted what that actually is.

JimWelsh · Nov 6, 2020

Randy Holmes-Farley said:
I cannot tell from the site you posted what that actually is.

Randy, wouldn't it be reasonable to infer that it has 500 PPM of alkalinity, expressed as mg/L CaCO3, which would be 10 meq/L, or 28 dKH?

CEReefer · Nov 6, 2020

EDIT didn’t see JimWelsh post

CEReefer · Nov 6, 2020

Now, if I dilute it 1:4 (making it 125mg/ml) that should be 7dKH, correct? That would make it within the readable range of the KHDirector

The point is.. what shall I dilute it with? Is RO/DI pure enough?

JimWelsh · Nov 6, 2020

CEReefer said:
I believe it is a solution containing 500mg/ml of CaCo3, I was wondering if there was a way to come up with the dKH, knowing the concentration.

FIrst, it's 500 mg/L, not 500 mg/mL, but even so, CaCO3 isn't soluble enough. It's simply not possible for it to actually contain literally 500 mg/L of actual CaCO3 in aqueous solution. However, alkalinity is often expressed in units of PPM as mg/L of CaCO3.

CEReefer · Nov 6, 2020

Got it.. I thought it was actually CaCo3.. so.. do you know of any alk reference solutions that are in the 4-14 dKH range that I could buy as a laboratory standard?

JimWelsh · Nov 6, 2020

CEReefer said:
Now, if I dilute it 1:4 (making it 125mg/ml) that should be 7dKH, correct? That would make it within the readable range of the KHDirector

The point is.. what shall I dilute it with? Is RO/DI pure enough?

Assuming my interpretation of the product you linked is correct, and it is 28 dKH, then 1 part of that solution mixed with 3 parts RO/DI would give you a 7 dKH solution, yes.

CEReefer · Nov 6, 2020

Thanks @JimWelsh ! Now my next question is, do you believe it is more prone to errors making a DYI alkalinity reference starting from the powder as suggested by Randy in a previous post, or diluting a premade lab grade solution?

Randy Holmes-Farley · Nov 6, 2020

JimWelsh said:
Randy, wouldn't it be reasonable to infer that it has 500 PPM of alkalinity, expressed as mg/L CaCO3, which would be 10 meq/L, or 28 dKH?

Yes, but what form it is is unknown to me. If it is sodium hydroxide, it may not work correctly. I’m not certain what the kh director actually does.

Randy Holmes-Farley · Nov 6, 2020

JimWelsh said:
Assuming my interpretation of the product you linked is correct, and it is 28 dKH, then 1 part of that solution mixed with 3 parts RO/DI would give you a 7 dKH solution, yes.

would a hydroxide solution give the correct value?

JimWelsh · Nov 6, 2020

Now, I see your point, Randy.

Dr. Jim · Nov 6, 2020

How about this product:

Saltwater Multi Reference Solution

The only reference solution based on a saltwater matrix that includes 8 of the most popular parameters for saltwater aquariums in a single solution. Fauna Marin’s Multi-Reference Solution is used to check your home water test kits for accuracy. Using your water test kits at home, you can measure...

www.bulkreefsupply.com

And, you can check the accuracy of many of your test kits with this Fauna Marin product.

And, BTW, I have the GHL 7.5 dKH Reference solution. What disappoints me with this solution is that the accuracy is +/- 0.2 dKH. So, if I'm not mistaken, that would mean if your KH Director measures any where between 7.3 and 7.7 with the Reference Solution, then you are as "good" as you can get, but that would just mean that any measurement you make on your tank water can be + or - 0.2 dKH. So, if you measure 8.0, it can really be anywhere from 7.8 to 8.2. It seems that for such a high-tech instrument, they should be able to come up with a more precise value.

CEReefer · Nov 6, 2020

Dr. Jim said:
How about this product:

Saltwater Multi Reference Solution

The only reference solution based on a saltwater matrix that includes 8 of the most popular parameters for saltwater aquariums in a single solution. Fauna Marin’s Multi-Reference Solution is used to check your home water test kits for accuracy. Using your water test kits at home, you can measure...

www.bulkreefsupply.com

And, you can check the accuracy of many of your test kits with this Fauna Marin product.

And, BTW, I have the GHL 7.5 dKH Reference solution. What disappoints me with this solution is that the accuracy is +/- 0.2 dKH. So, if I'm not mistaken, that would mean if your KH Director measures any where between 7.3 and 7.7 with the Reference Solution, then you are as "good" as you can get, but that would just mean that any measurement you make on your tank water can be + or - 0.2 dKH. So, if you measure 8.0, it can really be anywhere from 7.8 to 8.2. It seems that for such a high-tech instrument, they should be able to come up with a more precise value.

That’s another reason why I wanted something more “precise”, like a lab grade standard

Dr. Jim · Nov 6, 2020

Do you mean you want something more precise than the Fauna Marin or the GHL? (I think you mean GHL.....I guess we don't know the accuracy of the F.M. I plan to buy it soon to check it out).

But, I think the GHL standard is considered "lab grade." I'm not sure you will find something with an accuracy better than that. I have the Hanna standard and it is worse... about +/- about 10%!! (So a reading of 8.0 could be between 7.2 to 8.8 !! Useless!!

To be precise with the Hanna: Standard is at 98 ppm +/- 10 ppm

Gravity · Nov 6, 2020

Here is a good source for lab grade just going to cost more but they are fast and could get within a week for normal shipping. Or do the two day option for more money.