ALK Testing Results

[Jillianh]

Hello,
I have been using the Hanna checker to measure ALK in my mixed reef. After realizing that the numbers may have been influenced by old reagent, I purchased new reagent as well as a Red Sea foundations test kit. I run each of the two tests 2x each. The numbers I’m getting from the two tests are not in agreement.
Here are the actual numbers I’m getting:
Hanna ALK 7.8; 7.8
Red Sea ALK 6.8; 6.6
I would like to get my numbers in the 8 range, but based on the tests, I’m not sure how to dose.
My Ph is measuring fairly consistently at 8.0 (night) and 8.2 with Milwaukee probe.
My question is, can I infer any information from the Ph measurement and the above numbers as to the true measurement of ALK?

 

[((FORDTECH))]

Hello,
I have been using the Hanna checker to measure ALK in my mixed reef. After realizing that the numbers may have been influenced by old reagent, I purchased new reagent as well as a Red Sea foundations test kit. I run each of the two tests 2x each. The numbers I’m getting from the two tests are not in agreement.
Here are the actual numbers I’m getting:
Hanna ALK 7.8; 7.8
Red Sea ALK 6.8; 6.6
I would like to get my numbers in the 8 range, but based on the tests, I’m not sure how to dose.
My Ph is measuring fairly consistently at 8.0 (night) and 8.2 with Milwaukee probe.
My question is, can I infer any information from the Ph measurement and the above numbers as to the true measurement of ALK?

Go in the middle and call it 7.3 won’t hurt

 

[Miami Reef]

If you’re really curious, you can make an alkalinity standard and see how the Red Sea test kit preforms.

That standard won’t work for the Hanna checker though.

 

[Randy Holmes-Farley]

My question is, can I infer any information from the Ph measurement and the above numbers as to the true measurement of ALK?

Nope, sorry.

 

[Dburr1014]

Hello,
I have been using the Hanna checker to measure ALK in my mixed reef. After realizing that the numbers may have been influenced by old reagent, I purchased new reagent as well as a Red Sea foundations test kit. I run each of the two tests 2x each. The numbers I’m getting from the two tests are not in agreement.
Here are the actual numbers I’m getting:
Hanna ALK 7.8; 7.8
Red Sea ALK 6.8; 6.6
I would like to get my numbers in the 8 range, but based on the tests, I’m not sure how to dose.
My Ph is measuring fairly consistently at 8.0 (night) and 8.2 with Milwaukee probe.
My question is, can I infer any information from the Ph measurement and the above numbers as to the true measurement of ALK?

My question is, did you test at the same time of day on all of the test results? Alk swings will change results, obviously. I would choose a time of day to do the test, then compare and adjust as needed.

 

[flyingscampi]

What happens when you test a fresh batch of seawater. Which kit is closest to the salt manufacturer's published KH at your salinity level? Do both test kits retain the same margin between measurements?

If I get a suspect reading with the Hanna, I test with a Salifert kit which always measures up to 0.5 dKH lower than the Hanna.

 

[Jillianh]

I do test at the same time with both tests. I will test a fresh batch of saltwater and get a measurement from that. Perhaps a standard mix is is my future- or maybe purchase a third test?
Thank you all for the input. I’ve got a fairly new tank (Feb 22) and I would like to get it right before I run into a problem.

 

[flyingscampi]

Testing a fresh batch of seawater is good practice because if the KH, Ca, & Mg all differ from the manufacturer's published figures, it means your salinity is probably different to what you are measuring.

How salinity affects element levels is demonstrated on this label from a bucket of Red Sea’s ‘Coral Pro Salt’: