Which Test Kit's

[redpine42]

So my Apex "Lab Grade" salinity sensor has always been off, I ended up getting a Milwaukee salinity tester and use it as Truth.

My Ph has alway rangeed from 7.8 to 80 with my Apex "Lab Grade" sensor, but now I compare it to my Red Sea Ph test and the difference today is .4.

What is a good Ph sensor?

Also, don't care about ORP, but should I be concerned about the temp sensor also?

 

[chipmunkofdoom2]

pH test kits are good enough, but a properly-calibrated pH electrode will likely give you much better accuracy than a test kit. You also can't easily test that a kit is accurate, but you can easily double check the reading of a pH electrode in a solution of a known pH. Either the pH probe or the test kit could be right. Conversely, they both could be wrong. I would not assume either one is correct until you can calibrate the probe and get a more trustworthy answer.

Also, if by "Milkwaukee salinity tester" you mean the Milwaukee digital refractometer, it's worth mentioning that this device doesn't actually measure salinity. It measures refractive index, or how light passes through a sample of seawater. How important this is can be debated. I think it's always worth knowing what we're measuring because different measurement techniques are susceptible to different types of interference and inaccuracy.

 

[doughboy]

did you get your apex used? ph probe has a useful life and needs to be replaced when it can't provide a stable reading or hold calibration value. Just search for double junction ph probe on amazon. I've used pinpoint and milwaulkee brand and they are fine.

apex salinity probe is a pain to calibrate and not so easy to maintain it to give a good reading. It's like the elephant in the room no apex owner wants to talk about.

 

[redpine42]

did you get your apex used? ph probe has a useful life and needs to be replaced when it can't provide a stable reading or hold calibration value. Just search for double junction ph probe on amazon. I've used pinpoint and milwaulkee brand and they are fine.

apex salinity probe is a pain to calibrate and not so easy to maintain it to give a good reading. It's like the elephant in the room no apex owner wants to talk about.

All new, I did calibrate it, but that doesn't mean much too me. When I calibrated the salinity probe first time, I kept adding salt and it was going down. I knew there was something wrong and learned about the bubbles in the probe and re-calibrated.

 

[redpine42]

pH test kits are good enough, but a properly-calibrated pH electrode will likely give you much better accuracy than a test kit. You also can't easily test that a kit is accurate, but you can easily double check the reading of a pH electrode in a solution of a known pH. Either the pH probe or the test kit could be right. Conversely, they both could be wrong. I would not assume either one is correct until you can calibrate the probe and get a more trustworthy answer.

Also, if by "Milkwaukee salinity tester" you mean the Milwaukee digital refractometer, it's worth mentioning that this device doesn't actually measure salinity. It measures refractive index, or how light passes through a sample of seawater. How important this is can be debated. I think it's always worth knowing what we're measuring because different measurement techniques are susceptible to different types of interference and inaccuracy.

Well I just sent in my first ICP, we'll see which tests agree with it.

 

[redpine42]

Got a hanna ph/temp kit. Both Apex ph and temp are spot on!

 

[redpine42]

Yesterday both Hanna and Apex read 7.8 ph. I opened the windows and Hanna today reads 8.2 and Apex 8.0. I assume Hanna is the better measure.

 

[jda]

Any of those sensors can shift or fail. Remember that they are only hobby grade. I forgot about a PH probe about a decade ago - I do have a PH Pen that I use for water changes. Salinity should be with a quality refractometer calibrated with a known solution - never trust a probe or hydrometer.

pH can drastically change when you are away from the tank for even a few minutes. The CO2 can leave the water and the pH rise. I would not trust the pH of an ICP test to tell you what is in the tank. All of this said, if you have some aragonite sand and/or lots of live rock and your alk is good, then the PH is fine and you can forget about what value it actually is. Just open the house up to exchange air every once in a while.