Hanna alk checker off by almost 2 dkh?

[wanderer]

I’ve been using hanna alk checker. It’s been pretty consistent but recently I noticed the alk had increased more than expected. It was reading 10 yesterday. It was 10.5 five days prior. I rechecked using the diy test using 500 mL (drawn up with a 50 cc syringe 10x and then confirmed weight with a kitchen scale) and the diy test gave me 8.2

The alk reagent itself had an expiration date of 9/2023 though it was stored mostly in a cool dark place. I’m also at the last cc or 2 of the reagent so it’s possible the remainder is more concentrated

For another question. I have an apex and I disconnect the probe and attach it to a handheld pinpoint marine to check for the diy test (the two readings of tank water are identical). What’s the best way to use a checker? I could get another probe but I hate throwing them out every year. Is this my best option? Would litmus paper or a pH pen be good enough for the diy test ?

 

[lapin]

Note: Hanna sells Standards. You can use these to check if your checker is out of spec. You might also try replacing the battery.

 

[ThaBeast]

I’ve been using hanna alk checker. It’s been pretty consistent but recently I noticed the alk had increased more than expected. It was reading 10 yesterday. It was 10.5 five days prior. I rechecked using the diy test using 500 mL (drawn up with a 50 cc syringe 10x and then confirmed weight with a kitchen scale) and the diy test gave me 8.2

The alk reagent itself had an expiration date of 9/2023 though it was stored mostly in a cool dark place. I’m also at the last cc or 2 of the reagent so it’s possible the remainder is more concentrated

For another question. I have an apex and I disconnect the probe and attach it to a handheld pinpoint marine to check for the diy test (the two readings of tank water are identical). What’s the best way to use a checker? I could get another probe but I hate throwing them out every year. Is this my best option? Would litmus paper or a pH pen be good enough for the diy test ?

Hanna Alk reagent loses potency if not stored in the refrigerator once opened. I have recently switched to Salifert Kh test for alk and can repeat the test results consistently

 

[WhatCouldGoWrong71]

Yesterday with my Hanna I was getting wild swings. Turned out the battery was low. I didn't know that about the fridge trick.

 

[ThaBeast]

Yesterday with my Hanna I was getting wild swings. Turned out the battery was low. I didn't know that about the fridge trick.

There is a thread about it in the chemistry section here. Happened to me (2dkh + off with Hanna), fortunately I just had liverock in the tank and some coralline growing, was just monitoring stability to see when to add corals.

 

[wanderer]

Thanks for the responses. Makes sense that the reagent has gone bad. I think I’ll stick with the DIY testing since it’s pretty easy to do and pretty reliable as long as one has good ways to accurately measure