what test to trust
- Thread starter bobt2
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mcgyvr
New member
Assuming that both reagents are not expired and that you have performed more than one test and that you are testing correctly you trust neither at this point.. Get another test done to compare.. Got a fish store close that can test alk for you?
Bring your test kits to run all 3 at one time..
Bring your test kits to run all 3 at one time..
I doubt the 7.2 number, you would not have had great success with that number
NanoGeek0815
New member
You could always pick up a calibrated solution and find out which one is closer.
Sent from my SM-G975U using Tapatalk
Sent from my SM-G975U using Tapatalk
You use the same vial and sample for both the calibrate/control sample and the test sample w/ reagent? If not, I would not trust, if so, I would.
They give you two vials and a common mistake is using one for the first read and then the second w/ reagent for the second read. The test is all about measuring the refraction of light in the sample before the reagent is added--the control--to that after the reagent is added.
Using different vials/samples for these two steps introduces variability into the equation from vial imperfections and differences in the samples themselves. Best technique is to wear gloves, rinse the vial w/ tank water first, then add the tank sample (and measure w/ a pipette or something similar--NOT the line on the vial). Wipe the vial w/ a lint free cloth and ensure no air bubbles. Place vial in reader when instructed w/ the "10ml" facing forward. When instructed, remove vial, add the reagent, and gently invert 5-6 times to mix. Then wipe w/ lint free cloth again, check for air bubbles, and put back into reader w/ the "10ml" facing forward (this allows you to standardize the glass thickness).
Following this method I would trust over Salifert. I have always had trouble detecting the color change on their alk test which is why I switched. Other tests are fine (Ca and Mg).
Also, my tank runs about 7.6 and it is doing great. You could have had great success w/ an alk of 7.2 if it was stable. If I remember right, my alk was lower than what the Salifert was telling me too but I'd have to dig back through my logs to verify.
They give you two vials and a common mistake is using one for the first read and then the second w/ reagent for the second read. The test is all about measuring the refraction of light in the sample before the reagent is added--the control--to that after the reagent is added.
Using different vials/samples for these two steps introduces variability into the equation from vial imperfections and differences in the samples themselves. Best technique is to wear gloves, rinse the vial w/ tank water first, then add the tank sample (and measure w/ a pipette or something similar--NOT the line on the vial). Wipe the vial w/ a lint free cloth and ensure no air bubbles. Place vial in reader when instructed w/ the "10ml" facing forward. When instructed, remove vial, add the reagent, and gently invert 5-6 times to mix. Then wipe w/ lint free cloth again, check for air bubbles, and put back into reader w/ the "10ml" facing forward (this allows you to standardize the glass thickness).
Following this method I would trust over Salifert. I have always had trouble detecting the color change on their alk test which is why I switched. Other tests are fine (Ca and Mg).
Also, my tank runs about 7.6 and it is doing great. You could have had great success w/ an alk of 7.2 if it was stable. If I remember right, my alk was lower than what the Salifert was telling me too but I'd have to dig back through my logs to verify.
five.five-six
Well-known member
There has to be something quite wrong with either your methodology or the reagents in either one or both tests. .5 DKH variation would be unsurprising, anything over .75 would give me pause for concern. They are both very high quality kits and I would expect them to be very close if not exact. As mcgyvr said, I wouldn’t trust either until you get this figured out.
five.five-six
Well-known member
This^
I shoot for 8.0 DKH. Really the only reason to run at 9-10 is if you are having pH problems or going for slightly extra fast growth rate but running 9+ leaves you exposed to al sorts of potential problems that could be dogistrophic. Dip in nutrient levels, dip in Mg levels or a spike in alk can be much more harmful much faster if you are starting from a point of 10.0 DKH than if your starting point was 7.5-8.0.
Agree. Another thing with Salifert I noticed was sometimes my readings got a little off when I was near the bottom of the titrating reagent bottle. Always assumed evaporative loss over the 6 months or so for me to use it up just concentrated the solution--changing results over time.
But would assume this would cause a lower than actual reading since you would get color change sooner.
0.762 out!
boxfishpooalot
Active member
Hey make your own check solution its in my signature.
hkgar
Active member
There is a calabration checker for the Hanna.
https://www.saltwateraquarium.com/h...6MSqgoLYQAfp4buDa_jtkiWjgqkR4gXYaAgOvEALw_wcB
