What tests are most accurate for kh? Aquaforest salt low kh?

[kdubbz]

I switched to aquaforest salt a few months ago, had trouble keeping alk steady. Have to dose new salt, I measure to 1.025 salinity, mixed the bag and tested it with red sea kit, popped up as 5.6 Talked to fish store guy and he still recommends that one over the others so threw that bag out and tried a new bag and picked up an aquaforest kit which has a sample. Sample water included measured correct with aquaforest test kit but again the salt itself this time is measuring 6.7, red sea test kit showed 6.4, with the sample test showing perfectly I find it difficult to believe the tests are all way out of wack, but the salt itself is supposed to be tested on each batch. Magnesium was testing at 1430, calcium was 440 which was the only correct number. Is this a testing problem or a salt problem?
What other salts don't have crazy high alk? Most of the other ones I saw are 11-12 so when I do 20% water changes on my 30 gallon tank it spikes alk and makes things angry

 

[arking_mark]

How are you measuring salinity?

I suspect a salinity measurement issue if your Alk readings are correct.

Which salt are you using?

 

[Randy Holmes-Farley]

It's hard to say what the issue is. It is easy enough to add a little baking soda to the salt mix if you believe your test.

FWIW, raising the salinity to 35 ppt (sg = 1.0264) will also up the alk a bit.

As far as I can tell, there's no rationale for lower salinity in any reef aquarium (except salt cost).

 

[kdubbz]

How are you measuring salinity?

I suspect a salinity measurement issue if your Alk readings are correct.

Which salt are you using?

The top one! And using a refractometer that I calibrate every time!

 

[kdubbz]

It's hard to say what the issue is. It is easy enough to add a little baking soda to the salt mix if you believe your test.

FWIW, raising the salinity to 35 ppt (sg = 1.0264) will also up the alk a bit.

As far as I can tell, there's no rationale for lower salinity in any reef aquarium (except salt cost).

I was always worried about evaporation, I top up manually daily, but was worried I'd end up killing everything if it crept up any higher then 1.026 on hot days while I'm at work since its a smaller tank

 

[Randy Holmes-Farley]

I was always worried about evaporation, I top up manually daily, but was worried I'd end up killing everything if it crept up any higher then 1.026 on hot days while I'm at work since its a smaller tank

There's no concern about deaths at 1.027.

 

[arking_mark]

The top one! And using a refractometer that I calibrate every time!

I threw away my refactometer...I use a high-precision TM hydrometer.

Thread 'Salinity Measurement Troubles...' https://www.reef2reef.com/threads/salinity-measurement-troubles.835763/

Easy way to use a high-precision hydrometer is with a 500ml graduated cylinder...

Then I adjust my freshly calicrated EC meter offset to match.

 

[kdubbz]

There's no concern about deaths at 1.027.

That's fair! I started out with a 15 gallon, so I think my paranoia stems from there! Would magnesium being high in this salt be a problem if I upped the salinity a bit? Or not too bad unless it goes over 1500?

 

[Reef.]

Sounds to me it’s your salinity, if your Aquforest reference is correct then your salinity is most likely off. (But not by much)

AF at 1.025 has an alk of 7.4- 8, so your test reading of 6.7 is not far off the low end of the range, the salt in the bucket will not always match the label either.

Mag and cal are not the most accurate tests to read, so I wouldn’t take those readings as correct, alk is much easier to get a more reliable reading from.

I don’t think you have a big of an issue as you think.

 

[kdubbz]

Sounds to me it’s your salinity, if your Aquforest reference is correct then your salinity is most likely off. (But not by much)

AF at 1.025 has an alk of 7.4- 8, so your test reading of 6.7 is not far off the low end of the range, the salt in the bucket will not always match the label either.

Mag and cal are not the most accurate tests to read, so I wouldn’t take those readings as correct, alk is much easier to get a more reliable reading from.

I don’t think you have a big of an issue as you think.

Red sea test was reading magnesium at over 1500, aquaforest one was high 1400s if salinity was off on the low side then those numbers should reflect that considering the salt should be between 1250 and 1290 according to the bag correct?

 

[ti_lavender]

You can look up the individual batch results for the salt you have:

https://aquaforest.eu/en/icp-oes/

It's printed on the bag/bucket.

 

[Viperdragon]

I always make sure to mix the bag before I make water I have had this issue in the past with salt of some really high or low parameter cause things settled.

 

[Reef.]

Red sea test was reading magnesium at over 1500, aquaforest one was high 1400s if salinity was off on the low side then those numbers should reflect that considering the salt should be between 1250 and 1290 according to the bag correct?

Correct but as I said mag and cal are not easy to get a correct reading from a test kit, very unlikely your salinity is correct or a little low and your mag is 1500.,, even if high it would have to be way off for a 1500 reading to be correct.
AF is meant to be around 1350, so I would not be trusting your test kit.

AF also supply reference solution in their mag test kits, Salifert is also good for mag, but as said I would not test mag and get high reading then automatically think my salt was to blame.

AF is a very good salt, I would trust the salt more than your test results.

 

[kdubbz]

Red sea test was reading magnesium at over 1500, aquaforest one was high 1400s if salinity was off on the low side then those numbers should reflect that considering the salt should be between 1250 and 1290 according to the bag correct?

Yep, which I don't expect the mag to be accurate but if one thing is low and my salinity is off that should be low not wayy higher. use calibration fluid for my refractometer at 35ppt as well as using distilled to check if its hitting 0 so I feel like thats impossible that my salinity is that far off on the low end

 

[arking_mark]

Based on your original post...something is off if you trust your "low" Alk measurement. In my opinion its most likely one of three things:

1. Alk measurement is wrong and this is an Alk testing issue.
2. Alk measurement is correct and this is a concentration issue which would also result in low salinity.
3. Alk measuement is correct and you have a bad batch of salt.

As our hobby-grade test kits are prone to issues and user error, I'm betting on #1 or #2.

I experienced salinity testing issues using various testing equipment (including two refractometers) until I switched to the high-precision hydrometer. Hence my suspicion of #2.

Based on the salt you are using and your target salinity of 1.025, your expected Alk is 7.3 to 7.7. As our Alk kits are usually +/- 0.5 accuracy (or worse) a slightly lower salinity could produce a 6.7 Alk reading as that's within its accuracy range. So everything may be as it's supposed to.

If you really want to dive deeper, you have to triple check and verify that your measurements are accurate. This comes down to what test kits you trust.

 

[kdubbz]

Based on your original post...something is off if you trust your "low" Alk measurement. In my opinion its most likely one of three things:

1. Alk measurement is wrong and this is an Alk testing issue.
2. Alk measurement is correct and this is a concentration issue which would also result in low salinity.
3. Alk measuement is correct and you have a bad batch of salt.

As our hobby-grade test kits are prone to issues and user error, I'm betting on #1 or #2.

I experienced salinity testing issues using various testing equipment (including two refractometers) until I switched to the high-precision hydrometer. Hence my suspicion of #2.

Based on the salt you are using and your target salinity of 1.025, your expected Alk is 7.3 to 7.7. As our Alk kits are usually +/- 0.5 accuracy (or worse) a slightly lower salinity could produce a 6.7 Alk reading as that's within its accuracy range. So everything may be as it's supposed to.

If you really want to dive deeper, you have to triple check and verify that your measurements are accurate. This comes down to what test kits you trust.

Which is mostly why I made this post. I don't believe I have a salinity problem. If its a testing issue and im using 2 different test kits should I be trying a different one? Which ones are most accurate? Based on the test solution the aquaforest seems more accurate then the red sea one.

Should I just switch salts to a higher alk one and do smaller water changes? Or is there another salt on the lower spectrum that will work better?

The low alk i believe because I killed some euphyllia when my alk was testing below 7 with these kits and that stopped once I raised it above 8 and my new ones are healthy and thriving, but also the reason why I'm so worried about the alk and my salt.

 

[arking_mark]

Which is mostly why I made this post. I don't believe I have a salinity problem. If its a testing issue and im using 2 different test kits should I be trying a different one? Which ones are most accurate? Based on the test solution the aquaforest seems more accurate then the red sea one.

Should I just switch salts to a higher alk one and do smaller water changes? Or is there another salt on the lower spectrum that will work better?

The low alk i believe because I killed some euphyllia when my alk was testing below 7 with these kits and that stopped once I raised it above 8 and my new ones are healthy and thriving, but also the reason why I'm so worried about the alk and my salt.

Dying Euphyllia, or any livestock for that matter, usually triggers a cause and effect search. Something to remember with Coral is that often the initial cause is typically something that probably happened weeks before you noticed the impact.

If you're interested in why it may have died you should ask about that and be prepared to provide far more info on your tank and parameters...

But focusing back on the question. You trust your salinity and mostly trust your Alk reading from Aquaforest. That being the case, your salt isn't getting you the target parameters you're looking to keep. Simply change salts. I personally use TM Pro and am very happy with it except for the higher cost.

 

[gbroadbridge]

Which is mostly why I made this post. I don't believe I have a salinity problem. If its a testing issue and im using 2 different test kits should I be trying a different one? Which ones are most accurate? Based on the test solution the aquaforest seems more accurate then the red sea one.

Should I just switch salts to a higher alk one and do smaller water changes? Or is there another salt on the lower spectrum that will work better?

The low alk i believe because I killed some euphyllia when my alk was testing below 7 with these kits and that stopped once I raised it above 8 and my new ones are healthy and thriving, but also the reason why I'm so worried about the alk and my salt.

All hobby grade tests will not give you better than 0.3dkh accuracy, so if for example you are reading Alk at 7.0 it could be anywhere from 6.6 to 7.4.

That is absolutely normal with all the hobby tests out there, including the digital Hanna Checker.
Just pick a test, and try to keep the number, whatever it may be, stable.