Diluting samples to get within test kit range

[rhitee93]

Hi All,

Long story short, I've been waiting for a custom tank to show up for a few months as my re-entry into the hobby after 20 years. I know I am going to need a quarantine tank eventually, so I bought a little 10 gallon IM tank for that purpose. Since I have that tank, I decided to go ahead and set it up temporarily with some dry rock so I could run it through "the cycle". I'm really just doing this for fun, but it has helped me get back in the groove of testing and maintaining a tank.

I used Fritz bacteria, and added some Brightwell ammonia, and the cycle has gone pretty much as you would expect. It's been fun to watch the Seneye NH3 readings and how they compare the ammonia test from my Hannah kit. The ammonia is now down to 0.08ppm with the Hannah test after 7 days.

My Hannah master test kit only came with the ultra-low range nitrite test reagents, and I am still over the 200ppb range of the kit.

Am I right in thinking I could take the fully reacted sample, and keep doing dilutions with RODI water until I get within range to get an idea for where nitrites really are? I tired that today for the heck of it, and cut the sample in half 3 times before I got a valid reading. If this is at all valid, it would put my nitrites at 800ppb (0.8ppm)

There is no reason to really do this, I am just entertaining myself while I wait for my display tank to arrive :)

 

[SnazzyUrchin792]

You would need to do the dilutions in freshly-mixed saltwater.

 

[SnazzyUrchin792]

I would think you would have looked for this already, but some of the Hanna test kits include dilution instructions

 

[rhitee93]

I would think you would have looked for this already, but some of the Hanna test kits include dilution instructions

Ahh, I should check their website. I bought the marine master kit and it didn't really come with directions. It just walks you through the test with instructions on the screen for each step.

Hadn't considered sea water vs RODI as I was just thinking diluting the density of the color indicator, but sea water would indeed have a different absorbance than RODI water. I may play with that again tomorrow to see what happens. This is just for fun anyway.

 

[Randy Holmes-Farley Verified Community Expert]

Ahh, I should check their website. I bought the marine master kit and it didn't really come with directions. It just walks you through the test with instructions on the screen for each step.

Hadn't considered sea water vs RODI as I was just thinking diluting the density of the color indicator, but sea water would indeed have a different absorbance than RODI water. I may play with that again tomorrow to see what happens. This is just for fun anyway.

Density wouldn't matter. The concern between freshwater and seawater, when one exists for a given kit, is usually based on the relative pH buffering of those samples.