Hana ALK tester maybe not reading right?

[Gadbery]

So have been using the Hanan Dkh tester for 3 months now. My tank always would sit around 8.4ish and over a week dip to maybe 7.8 (no dosing as im just starting to dose Randys 2 part recipe 1)
When i mix a fresh salt water batch weekly for water changes (Red Sea Pro mixed to 1.025) its Dkh measures around 10 normally.

issue
last week iv measured my tank 3 times and get 6.2-6.4dkh (apex probe reads 8.2, though i use apex as a graph for change not exact value) tested fresh made salt water and it read 8 this time.... So im either losing my marbles and testing wrong all of sudden or my hana checker is giving me 2dkh off readings? Will add the reagent is about 3 months old i have ordered a new batch just waiting on it so could be the issue. Im taking a water sample to LFS today to get tested to see what numbers they are showing.

Figured id ask if any one has noticed this before

 

[legalizedreefer]

So have been using the Hanan Dkh tester for 3 months now. My tank always would sit around 8.4ish and over a week dip to maybe 7.8 (no dosing as im just starting to dose Randys 2 part recipe 1)
When i mix a fresh salt water batch weekly for water changes (Red Sea Pro mixed to 1.025) its Dkh measures around 10 normally.

issue
last week iv measured my tank 3 times and get 6.2-6.4dkh (apex probe reads 8.2, though i use apex as a graph for change not exact value) tested fresh made salt water and it read 8 this time.... So im either losing my marbles and testing wrong all of sudden or my hana checker is giving me 2dkh off readings? Will add the reagent is about 3 months old i have ordered a new batch just waiting on it so could be the issue. Im taking a water sample to LFS today to get tested to see what numbers they are showing.

Figured id ask if any one has noticed this before

Wait… what do you mean your Apex probe? Only way for apex to read DKH is through the trident. Are you confusing the PH probe with DKH?

also, how hanna reagent I’ve read to keep it refrigerated and do your absolute best to make sure sure it doesn’t get contaminated with anything else

 

[homer1475]

3 month old unrefrigerated reagent, would read low. I always have a salifert kit around if something starts reading wacky on the hanna.

Keep the reagent refrigerated, or use it up faster. I've noticed after about a month into using the same reagent bottle, it starts to read low.

 

[Timfish]

I was not impressed when I got my Hanna alkalinity tester. Went to a friends house and checked mine against thiers withthe same sample of water. Using both reagents in both testers we got 4 results that varied .9 dKH between highest and lowest readings.

 

[Gadbery]

3 month old unrefrigerated reagent, would read low. I always have a salifert kit around if something starts reading wacky on the hanna.

Keep the reagent refrigerated, or use it up faster. I've noticed after about a month into using the same reagent bottle, it starts to read low.

interesting ill have to start doing that and kkeep all liquid reagents in my fridge. I have a realy hard time with color shade testers so i prefer using hanna. Ill see what the LFS says today and look at snagging a back up test kit

 

[Gadbery]

I was not impressed when I got my Hanna alkalinity tester. Went to a friends house and checked mine against thiers withthe same sample of water. Using both reagents in both testers we got 4 results that varied .9 dKH between highest and lowest readings.

Ya my issue is i have hard time picking out different shades of a color on some of the other test kits. Like saliferts nitrate kit anything on the lower end all look the same to me. My hanna had always given me consistent results till now but as holmer mentioned a 3 month old reagent very well may be the cause. At the end of the day knowing the 100% accurate result isnt my goal as long as i get stable readings staying in a desired range. but the -2dkh was alarming for sure.

 

[billyocean]

A couple of factors..refrigeration and shaking before use is key. Also Saltwater Aquarium has sent out HI755s reagent when HI772s is what you need. The HI755s is consistent but it WILL read about .6 lower..forget exact number. So make sure you have HI772s to start with.

 

[Gadbery]

Verified my old reagent was HI772s. The new one I ordered came in today and I ran a test with both reagents.
old - 5.8
New - 8.7

so was definitely the reagent gone bad. Will refrigerate it going forward!

 

[n2585722]

Verified my old reagent was HI772s. The new one I ordered came in today and I ran a test with both reagents.
old - 5.8
New - 8.7

so was definitely the reagent gone bad. Will refrigerate it going forward!

Fauna Marin makes a Multi Reference solution you can use to check your checkers with. Here is a link https://www.coralvue.com/fauna-marin-multi-reference-100ml .

 

[Gadbery]

Fauna Marin makes a Multi Reference solution you can use to check your checkers with. Here is a link https://www.coralvue.com/fauna-marin-multi-reference-100ml .

Thanks, i like the idea of a reference solution to verify checker and stuff!!

 

[n2585722]

I got some and tested all of my testers recently. I am ok with the error range considering that these are not lab grade test. Below is a screenshot of the results. The phosphate checker I also did a test using the old reagent and it was off quite a bit in the opposite direction. So it looks like reagent could be the largest variable on these.