Seachem Marine pH and Alkalinity Test Kit

[LucidGoblin]

The instructions on the Seachem Marine pH and Alkalinity test kit state: "Each drop [of alkalinity reagent] is equal to 0.5 meq/L. The number of drops to get to yellow [from blue] divided by 2 is the total alkalinity." It took 4 drops of reagent for my test sample to change color. Does this mean my Alkalinity is only 2? According to the test kit, "aquarium water should have a total alkalinity of 4-6 meq/L." So my alkalinity is only half of what it should be, correct?
This worried me, so I dissolved 1 1/4 tsp. of baking soda in 1 cup of hot distilled water, let it cool, and started a slow drip into the sump area of my 30 gallon tank. Does anyone have any input or advice on this method?

 

[Dan_P]

What was the alkalinity after adding the baking soda? What is the salinity level in the aquarium?

 

[nereefpat]

Your math is correct. 4 drops would equal 2 meq/L.

The 4-6 meq/L recommendation is wrong, however. 4 meq/L = more than 11dKH, which is too high. 6 meq/L = 17 dKH, which is WAY too high. 3 meq/L (8.5 dKH) would be a better target. Bring it up slowly with baking soda, as you are doing.

 

[LucidGoblin]

Thanks for the replies. After running the baking soda drip throughout the night, the test changed color after 7 drops this morning. This would suggest an alkalinity of 3.5 meq/L. I'll do a small water change later to see if it'll bring it down a little bit, but I haven't seen any abnormal behavior from any of the tank inhabitants, so I think we're good.
(I have a DIY distilled water drip system that keeps my salinity at a constant 1.026.)

 

[bertoni]

I would target more like 3-4 meq/L with that kit. 2.5 meq/L is fine, but I'd leave some margin for testing error. 3.5 meq/L is fine.