water testing

[demifelix]

I just got back into reefing recently, broke down my main tank and started all over. It's been running for 2 months now. All parameters seem to be in check, but last week I decided to just calibrate my test kits (just for the sake of it since the kits are like 2 years old - but not yet reached the expiration date yet). I found that using the control solution my alk reads around 9.5 although the control solution is supposed to only read around 6.7 (+- .3). My tank water reads around 8.5 from the test. Does that mean that my alk test is way off and the actual alk of my tank water is only around 5? Can the control solution be bad prior to the expiration date? My other tests don't have the control solution so I can't say, but now I'm just skeptical. Any help is appreciated. Thanks.
Felix

 

[marquiseo]

demifelix;971229 wrote: I just got back into reefing recently, broke down my main tank and started all over. It's been running for 2 months now. All parameters seem to be in check, but last week I decided to just calibrate my test kits (just for the sake of it since the kits are like 2 years old - but not yet reached the expiration date yet). I found that using the control solution my alk reads around 9.5 although the control solution is supposed to only read around 6.7 (+- .3). My tank water reads around 8.5 from the test. Does that mean that my alk test is way off and the actual alk of my tank water is only around 5? Can the control solution be bad prior to the expiration date? My other tests don't have the control solution so I can't say, but now I'm just skeptical. Any help is appreciated. Thanks.
Felix

Which test kit? The control solution is that for a reason. It is the one variable that doesn't change. If it is wrong then something is off.

 

[acroholic]

The standard solution could be bad, or the kit reagents bad, or both. You could test your water, then take a sample to a LFS for comparison. I usually replace my test kits yearly.

I would get new test kits myself.

 

[demifelix]

Salifert kit.

Yeah Dave, I'll take the water to a LFS and probably get new kits.

 

[acroholic]

demifelix;971482 wrote: Salifert kit.

Yeah Dave, I'll take the water to a LFS and probably get new kits.

I use the Salifert KH test, and I have used the standard, and they have always matched up very closely, so I'd say it is probably the age of the kit. But my KH test was not very old.

It will be interesting to hear what your results are. Not sure about KH standards, but pH probe calibration solutions usually come with expiration dates.