Don't use old test kits!

[hatfielj]

Just a word of caution from my experience.
I just set up a new system a couple weeks ago and I've been adjusting my Alk/Ca/Mg levels ever since. I've been using some old Salifert test kits that technically weren't expired yet, but had been used from my previous system which was taken down over a year prior.

I got my levels where I thought they should be just today using the same test kits. However, I also received new kits in the mail today since my old ones were just about gone...I re-tested my levels and my calcium was 500!! The old test kit was reading 410! I'm assuming this may be due to some sort of evaporative issue making the Ca-3 solution more concentrated than it should be, thus resulting in a false low reading? I dunno? I noticed the same problem with my expired Mg test kit. It was reading a level of like 990, but when I replaced it with a new test kit and rechecked my levels were actually over 1400! The alkalinity test kits old and new read similar levels thankfully.

SO, if you have old Ca and Mg test kits, don't use them. It's better to be safe than sorry and replace them when they get old.

 

[Brew12]

Just a word of caution from my experience.
I just set up a new system a couple weeks ago and I've been adjusting my Alk/Ca/Mg levels ever since. I've been using some old Salifert test kits that technically weren't expired yet, but had been used from my previous system which was taken down over a year prior.

I got my levels where I thought they should be just today using the same test kits. However, I also received new kits in the mail today since my old ones were just about gone...I re-tested my levels and my calcium was 500!! The old test kit was reading 410! I'm assuming this may be due to some sort of evaporative issue making the Ca-3 solution more concentrated than it should be, thus resulting in a false low reading? I dunno? I noticed the same problem with my expired Mg test kit. It was reading a level of like 990, but when I replaced it with a new test kit and rechecked my levels were actually over 1400! The alkalinity test kits old and new read similar levels thankfully.

SO, if you have old Ca and Mg test kits, don't use them. It's better to be safe than sorry and replace them when they get old.

Great advice!

I would also add to it that you should order your next test kit prior to running out of the old one. That way you can overlap tests to see how close they read. This can be important in maintaining system stability.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the reminder.

 

[ajm83]

It could also be that the new test kit is misreading...

 

[Daniel@R2R Verified Admin]

Yep. Those things have an expiration date. Definitely be sure to check it. Thanks for reminding me. *going to check test kits now*

 

[anthonys51]

A mg text of 990 would indicate to me something is wrong with the test Randy can chime in but I don’t think it’s possible in a new tank

 

[Cory]

Ive noticed the same thing! The only way to be sure is to make a standard.

For alk you can use 1.135 grams of sodium bicarbonate and 1 gallon of ro/di will be 10 dkh. May not work with Hanna checker. But will with acid based titration like salifert.

 

[ajm83]

Well I've just replaced my salifert mag test and I've got the same thing.

Old kit - expiry 09/2019 - reading 1335
New kit - expiry 04/2021 - reading 1425

Double tested, same result twice in a row. Probably explains why every bucket of salt I would buy had (apparently) low mag levels...!

Interestingly the KH and Calcium tests are near enough bang on with the new and old within 3%

 

[Kershaw]

Out of curiosity could leaving them open or possible contamination. Cause readings to be off. Or maybe not cleaning the test tube well enough, or syringes they come with. Just wondering. Thanks.

 

[ajm83]

Out of curiosity could leaving them open or possible contamination. Cause readings to be off. Or maybe not cleaning the test tube well enough, or syringes they come with. Just wondering. Thanks.

Don't know, but I clean my tubes with RODI every use and always cap the reagents and store them upright, in a cupboard at room temp so I don't think that's what's happened to mine.

 

[Drewbacca]

I am out of reagent for my hanna calcium test which i was using because trident is erroring on calcium only.. but i have an expired red sea pro test.. based off this experience of yours.. im thinking i could test with it for now and at least know what the minmum is and that its prob higher? Maybe even test some fresh mixed sw to see what the general range is? Thoughts?

 

[Randy Holmes-Farley Verified Community Expert]

I am out of reagent for my hanna calcium test which i was using because trident is erroring on calcium only.. but i have an expired red sea pro test.. based off this experience of yours.. im thinking i could test with it for now and at least know what the minmum is and that its prob higher? Maybe even test some fresh mixed sw to see what the general range is? Thoughts?

Assuming if or how the kit may be off is tricky. Trying on some new salt water and at least knowing the tank tank is near the new salt water (or not) may be fine until you get a newer test.

 

[SteveMM62Reef]

I have the old SeaTest Kits, and had a source for the powdered Reagents, till 2018. Even though they are expired, they still work. Spot on with more expensive recent test kits. Wish they’d bring them back. Also I have a Low Range Chorine Test Kit, for Tap Water, that looks just like the SeaTest. Can’t find the Reagents anywhere!