Understanding the Salifert KH/Alkalintity Test

[jmc]

I have started dosing my 46 gal w/10 gal sump FOWLR with 2-part Calcium/Buffer system (B-Ionic) using manufacturers directions. I tested for KH and Alkalinity with a Salifert test kit and with two tests wound up with .25 ml KH reagent left in the syringe.

The instructions say to do some simple math to determine both values:

KH in dKH = (.25x16) 4
Alk in meq/L = (.25 x 5.71) 1.43

The instructions also has a table where it looks like readings [from left over reagent in the syringe] translate into KH and Alk values - huge differences from what is computed in example above.

Can someone tell me how to definitively use this test?? If I use the values derived by the multipliers I'm way low in both KH and Alk but don't know how this could be if I'm dosing and already have calcium present from my salt mix...

Based on these readings, should I remain dosing at product instructions or increase?

 

[steve-s]

I've never bothered with the calculation myself. I simpley use the chart provided. 0.25 ml on the syringe would yield a reading of 12 DKH or 4.29 mEq/l. That is the upper level of where alkalinity should be maintained. Higher values will not benefit the tank in any real sense.

Just to clarify your math though, your calculation is wrong.
(1-0.25)x16 = 12 DKH
(1-0.25)x5.71 = 4.2825 mEq/l

Cheers
Steve

 

[jmc]

steve-s,

Thank you - I was not subtracting the remaining reagent from the 1 ml total volume...

So, my tests indicate that both may KH and Alk are at the high end... How do I translate this into how much Calcium/Buffer I should be dosing? I've got 75 lbs of LR. I started noticing dieback in my coraline algae - hence the dosing. Is the Calcium/Buffer going to bring KH/Alk down?

Thanks again!

 

[steve-s]

How do I translate this into how much Calcium/Buffer I should be dosing? I've got 75 lbs of LR. I started noticing dieback in my coraline algae - hence the dosing.

Coralline die off can be caused by many things so don't be in too much a hurry to elevate numbers in hopes of spuring new growth. Simpley target NSW levels (at the higher end if you wish) and seed the water column with spores. Simpley placing a powerhead in front of a heavily incrusted area will do plenty. You can even scrap it or rub it with a toothbrush.

As far as what you should dose and how often, that will depend on your rate of depletion. I would hold off on any further dosing for the next few days at least and test daily recording the results. Once you can determine what the depletion rate is (if any), then you can determine how much product may be required.

Is the Calcium/Buffer going to bring KH/Alk down?

Buffer maintains the alkalinity so you don't need any help there. Before you can do much more you should post the Ca numbers. It is equally important to maintain the balance between alk/Ca as maintaining the chem overall. Check your >>http://www.andy-hipkiss.co.uk/caalkcalc.htm]balance here[/url]<< and see what you come up with. Once things are balanced then start testing instead of dosing to map the rate of depletion. Don't knock yourself out looking for exact numbers though, just be in the general range.

Depending on the level of Mg, Ca additions will impact alkalinity even if slightly and force the numbers down some. I would post your complete numbers before you do though.

Cheers
Steve