RedSea vs API readings?

[jiggysmb]

I have noticed my API kit readings are always much different than my RedSea. Any advise on which I should be following or do I assume my numbers are somewhere in the middle? Is there another test kit I should be using?

For example,
PH - API 7.8 vs RedSea 8.1
KH - API 10 vs RedSea 8
PO4 - API 0 vs RedSea .25

 

[EricR]

I'm sure most will say Red Sea over API.
Time for an alkalinity reality check on another test kit or have your LFS check it.

Only API/RedSea crossover I have is pH and they, surprisingly, always match (whenever I spot check).

 

[jiggysmb]

I'm sure most will say Red Sea over API.
Time for an alkalinity reality check on another test kit or have your LFS check it.

Only API/RedSea crossover I have is pH and they, surprisingly, always match (whenever I spot check).

I assume many will say redsea but the funny thing is I use Reef Crytal salt and that is 13dkh according to manufacturer, 10-11dkh according to other posts. I mixed up a 5 gallon bucket to proper salinity and tested with both and the API showed 10 which is closer, the RedSea showed 8 which threw me off and made me question RedSea since it showed it was so much lower than it is supposed to be.

 

[EricR]

I assume many will say redsea but the funny thing is I use Reef Crytal salt and that is 13dkh according to manufacturer, 10-11dkh according to other posts. I mixed up a 5 gallon bucket to proper salinity and tested with both and the API showed 10 which is closer, the RedSea showed 8 which threw me off and made me question RedSea since it showed it was so much lower than it is supposed to be.

Interesting -- I use Red Sea for alkalinity and my alk has always been low (6.0)
Hanna digital checker for alk (dKH) is scheduled to be delivered this afternoon so we'll see...

 

[nereefpat]

My post from the other thread:

I would say the pH readings are close enough to being the same. And I wouldn't worry about pH anyway.

Once phosphates are close to natural seawater range, the color comparison type kits aren't very useful. The Hanna Ultra low range kits are really the only kits useful in our range.

Both alk kits should work fine. Stability is more important than a specific number. FYI, you can lower the resolution of the API kit by increasing the test sample volume. For example, if you double the sample volume each drop will equal 0.5 dKH instead of 1.0 dKH.

 

[EricR]

Interesting -- I use Red Sea for alkalinity and my alk has always been low (6.0)
Hanna digital checker for alk (dKH) is scheduled to be delivered this afternoon so we'll see...

Only in case of interest to jiggysmb -- my Hanna dKH checker showed up so I ran my first test (comparing to test of same tank water with Red Sea titration test, done at same time)

Red Sea = 6.0 dKH (consistent at this for months)
Hanna = 6.7 dKH

Next stop -- run both tests again and have LFS test on my next trip there (probably this or next weekend)

 

[jiggysmb]

Only in case of interest to jiggysmb -- my Hanna dKH checker showed up so I ran my first test (comparing to test of same tank water with Red Sea titration test, done at same time)

Red Sea = 6.0 dKH (consistent at this for months)
Hanna = 6.7 dKH

Next stop -- run both tests again and have LFS test on my next trip there (probably this or next weekend)

Thank you for posting your findings!

 

[EricR]

Thank you for posting your findings!

...and yet another update (dead thread anyway so what the heck):

LFS test vs Home tests, new comparison (same water sample):
LFS test = 6.4 dKH
Home Hanna = 6.3 dKH
Home Red Sea = 5.5 dKH

 

[nereefpat]

What is the LFS using for alk test ?

 

[EricR]

What is the LFS using for alk test ?

Oh,,, yeah...

LFS said they use "Red Sea Pro" kits for most parameters, whatever that means.
Didn't see any boxes of the actual kits but for sure they were not using any Hanna digital testers and were doing some kind of titration test for the alk.

*aside, my home Red Sea pH/Alk kit is titration (for alk) and the reading steps are in 0.5 dKH increments so no more granular than that (...5.5, 6.0, 6.5, etc)

 

[nereefpat]

Oh,,, yeah...

LFS said they use "Red Sea Pro" kits for most parameters, whatever that means.
Didn't see any boxes of the actual kits but for sure they were not using any Hanna digital testers and were doing some kind of titration test for the alk.

*aside, my home Red Sea pH/Alk kit is titration (for alk) and the reading steps are in 0.5 dKH increments so no more granular than that (...5.5, 6.0, 6.5, etc)

Pro is just a box that contains 3 kits for Alk, Ca, and Mg.

Titration is best, and 0.5 dKH resolution is plenty close enough.

 

[EricR]

Pro is just a box that contains 3 kits for Alk, Ca, and Mg.

Titration is best, and 0.5 dKH resolution is plenty close enough.

I wonder how my LFS came up with 6.4 dKH -- might have to ask for more details next time I'm there. (I assumed they had some high resolution test,,, maybe the guy just said, "uhhh, almost 6.5 but not quite,,, I'll call it 6.4" ... DOH!)

For now (at home), I guess I'm trusting my Hanna digital.

 

[nereefpat]

"uhhh, almost 6.5 but not quite,,, I'll call it 6.4" ... DOH!)

That sure could be. If he was using a Salifert titration kit, 6.4 dKH would be a possible outcome. It goes by 0.3 increments.

 

[jiggysmb]

...and yet another update (dead thread anyway so what the heck):

LFS test vs Home tests, new comparison (same water sample):
LFS test = 6.4 dKH
Home Hanna = 6.3 dKH
Home Red Sea = 5.5 dKH

I was told by a pretty knowledgeable guy that APIs KH is more reliable than red sea, as well as nitrate and phosphate. He used Red Sea strictly for calcium, magnesium and a few others