Contradicting salinity results

[Night Reefer]

I have a 180 gallon set up with 70 gallon sump. I set the sump up to use the triton method. I set up my apex unit and started adding Coral pro salt. I added salt to cover 200 gallons of water. I figured I would get the additional salt once the tank settled after a day or two. Well after three days apex reported my salt was at 54. This confuse the hell out of me I know my rocks and my sand can’t be taking up 70 gallons of water. I went ahead and did a water change and then realized that the problem may not be the probe is not correct. So I pulled out my refractometer and it showed 25. I contacted Apex and did recalibration and it showed 26 to 27. At this point I added additional salt to cover 55 gallons of water of the same Red Sea product. After a day my apex unit is reading 32.2. I recalibrated my refractometer and it is now reading 34.5. If it was .5 off it would be no big deal maybe even 1 but to be 2.3 off it’s too much . What should I believe???? Temps. are at 77-78 Refractometer was purchased from BSR. Also I noticed as I enter the additional sold my pH is dropping. I have no lights on during the cycle and my pH is currently at 7.65.

 

[Tony Thompson]

I don`t` know for certain why your probe seems to have an apparent discrepancy. But I use Tropic Marin salts and I know the Bio Active version gives a false reading on my conductivity probe. This is explained on the products info sheet. Is it possible the elevated params of Coral Pro Salt can throw of the conductivity probe. I must admit I do not know enough about the chemistry involved.

Have you tried the probe in a fresh mix before you put it in the tank, just to make sure there is no interference. Would be interesting to see if their is still a discrepancy. Also if the probe is in the water when you add the salt, maybe this caused some problem. I always wait for my salt to dissolve before putting my probe in.

I am sure some one with more knowledge will explain.

Following with interest.

 

[Randy Holmes-Farley Verified Community Expert]

I don`t` know for certain why your probe seems to have an apparent discrepancy. But I use Tropic Marin salts and I know the Bio Active version gives a false reading on my conductivity probe. This is explained on the products info sheet. Is it possible the elevated params of Coral Pro Salt can throw of the conductivity probe. I must admit I do not know enough about the chemistry involved.

Have you tried the probe in a fresh mix before you put it in the tank, just to make sure there is no interference. Would be interesting to see if their is still a discrepancy. Also if the probe is in the water when you add the salt, maybe this caused some problem. I always wait for my salt to dissolve before putting my probe in.

I am sure some one with more knowledge will explain.

Following with interest.

Do you have a link to that claim about false readings? I don’t believe it. [emoji3]

 

[Randy Holmes-Farley Verified Community Expert]

I have a 180 gallon set up with 70 gallon sump. I set the sump up to use the triton method. I set up my apex unit and started adding Coral pro salt. I added salt to cover 200 gallons of water. I figured I would get the additional salt once the tank settled after a day or two. Well after three days apex reported my salt was at 54. This confuse the hell out of me I know my rocks and my sand can’t be taking up 70 gallons of water. I went ahead and did a water change and then realized that the problem may not be the probe is not correct. So I pulled out my refractometer and it showed 25. I contacted Apex and did recalibration and it showed 26 to 27. At this point I added additional salt to cover 55 gallons of water of the same Red Sea product. After a day my apex unit is reading 32.2. I recalibrated my refractometer and it is now reading 34.5. If it was .5 off it would be no big deal maybe even 1 but to be 2.3 off it’s too much . What should I believe???? Temps. are at 77-78 Refractometer was purchased from BSR. Also I noticed as I enter the additional sold my pH is dropping. I have no lights on during the cycle and my pH is currently at 7.65.

Many people have issues with controllers and conductivity measurements, but you are giving very confusing numbers without units so I can’t really understand. For example, 35 ppt seawater has a conductivity of 53 mS/cm and a sg of 1.0264.

 

[Tony Thompson]

Do you have a link to that claim about false readings? I don’t believe it. [emoji3]

Hi Randy, hope you are having a great spring break.

Its Tropic Marine themselves that state this. I noticed it once I read the instructions, Something I should do at the beginning and not the end. ha ha. Her is the statement from their website.

"Note: The review of the conductivity of freshly prepared BIO-ACTIF seawater will show about 10 % too low results. We recommend measuring the specific gravity with the Tropic Marin® HYDROMETER."

 

[Night Reefer]

Many people have issues with controllers and conductivity measurements, but you are giving very confusing numbers without units so I can’t really understand. For example, 35 ppt seawater has a conductivity of 53 mS/cm and a sg of 1.0264.

The numbers I listed are in ppt. Refractometer is measuring Higher than the apex salinity probe. The probe was just calibrated the second time the with technical support from Apex. I did shake the probe to remove any air bubbles that might’ve been in there.

 

[Randy Holmes-Farley Verified Community Expert]

Hi Randy, hope you are having a great spring break.

Its Tropic Marine themselves that state this. I noticed it once I read the instructions, Something I should do at the beginning and not the end. ha ha. Her is the statement from their website.

"Note: The review of the conductivity of freshly prepared BIO-ACTIF seawater will show about 10 % too low results. We recommend measuring the specific gravity with the Tropic Marin® HYDROMETER."

Thanks. Just had a nice walk with the family at a local nature preserve!

I do not believe they are correct on the conductivity issue. There's no reason for this to be true unless they have not fully dissolved the salt mix.

 

[HB AL]

"Note: The review of the conductivity of freshly prepared BIO-ACTIF seawater will show about 10 % too low results. We recommend measuring the specific gravity with the Tropic Marin® HYDROMETER."

My first thought was they are pushing people to purchase "there" hydrometer, because other brands won't be accurate with "there" salt. I have no idea if that's an accurate statement from them but I'm sure someone in there marketing department is doing there job to create more revenue$$$$$

 

[Tony Thompson]

My first thought was they are pushing people to purchase "there" hydrometer, because other brands won't be accurate with "there" salt. I have no idea if that's an accurate statement from them but I'm sure someone in there marketing department is doing there job to create more revenue$$$$$

Its only Conductivity that they say will show discrepancy 10% low. Not a refractometer or Hydrometer. It is only mentioned for the Bio Active Salt. They do not say this for any of their other salts.

Thanks. Just had a nice walk with the family at a local nature preserve!

I do not believe they are correct on the conductivity issue. There's no reason for this to be true unless they have not fully dissolved the salt mix.

I use Tropic Marin salt on a regular basis. I sometimes use the Bio Active but generally use the Pro Reef. The levels of both are the same but the Bio Active has slightly higher Alk 8 dKH compared to 7dKH on the Pro Reef.

I never read my salinity till after the salt has mixed for at least 12 hours overnight, so I have not noticed the 10% difference. I always measure conductivity with my Hanna meter.

I must say that the Bio Active salt certainly doese produce a notable reaction in my LPS corals. (10% water change) They seem to inflate their polyps more than usual. Similar to when I dose my Prodibio or Polyplab Poly Booster before feeding reef roids. I have not noticed this reaction with the Pro Reef salt.

I have spoken to the guys at Tropic Marin Before and they where very amenable. I will have a chat with them and ask for an explanation on the 10% difference on conductivity. I will post the answer after the holiday break.

 

[Randy Holmes-Farley Verified Community Expert]

Its only Conductivity that they say will show discrepancy 10% low. Not a refractometer or Hydrometer. It is only mentioned for the Bio Active Salt. They do not say this for any of their other salts.


I use Tropic Marin salt on a regular basis. I sometimes use the Bio Active but generally use the Pro Reef. The levels of both are the same but the Bio Active has slightly higher Alk 8 dKH compared to 7dKH on the Pro Reef.

I never read my salinity till after the salt has mixed for at least 12 hours overnight, so I have not noticed the 10% difference. I always measure conductivity with my Hanna meter.

I must say that the Bio Active salt certainly doese produce a notable reaction in my LPS corals. (10% water change) They seem to inflate their polyps more than usual. Similar to when I dose my Prodibio or Polyplab Poly Booster before feeding reef roids. I have not noticed this reaction with the Pro Reef salt.

I have spoken to the guys at Tropic Marin Before and they where very amenable. I will have a chat with them and ask for an explanation on the 10% difference on conductivity. I will post the answer after the holiday break.

Great, thanks. Maybe Lou Ekus can just post their rationale here so we can understand and debate it.

 

[Tony Thompson]

Great, thanks. Maybe Lou Ekus can just post their rationale here so we can understand and debate it.

That would be great. I wasn't aware the Tropic Marin USA where on this forum. I have left a message for the guys in Germany as well so hopefully we may be enlightened. Best wishes.

 

[Randy Holmes-Farley Verified Community Expert]

That would be great. I wasn't aware the Tropic Marin USA where on this forum. I have left a message for the guys in Germany as well so hopefully we may be enlightened. Best wishes.

He sometimes pops in when he thinks I’m not being fair to their products. [emoji23]

 

[Night Reefer]

This went way off subject. Lol

 

[Randy Holmes-Farley Verified Community Expert]

The numbers I listed are in ppt. Refractometer is measuring Higher than the apex salinity probe. The probe was just calibrated the second time the with technical support from Apex. I did shake the probe to remove any air bubbles that might’ve been in there.

Which refractometer?

Did you calibrate it with a seawater 35 ppt standard? If so, I’d believe it. If not, maybe it is not even the right type of refractometer??

 

[Tony Thompson]

Sorry Night Reefer, I sincerely apologize.

I hope you don't feel your question has been sidetracked. If you would prefer I could try and start a new thread.

It could be a number of things. It may be something as simple as a problem with the probe, the refractometer. or even a margin of error. Impossible to tell at the moment.But please stick with it. Lets start by investigating the salt mix itself first, that way we may even learn a little about what may or may not cause a discrepancy in conductivity.

My field is Electronic Engineering not Chemistry. We are lucky to have the attention of a very qualified and respected member of our reefing community to shed some light on the matter.

With a little luck we may also grab the attention of others that may have an explanation.

The only advice I could offer is test your probe against a known reference. That way you can investigate the possibility that the probe is not drifting off calibration. You could also test the refractometer against a reference solution. of 35ppt @25c. Does the apex salinity probe give a reading in mS/cm?

Its late here in England, I just noticed your comment and felt the need to apologize. I will check back in the morning. Best wishes.

 

[Randy Holmes-Farley Verified Community Expert]

If you used a perfectly made salt refractometer (most are) and calibrated perfectly with ro/di, it WILL read 1.7 ppt too high in seawater . That sounds like it matches your current variance fairly well.

 

[Tony Thompson]

Sorry I must have missed something. What make of refractometer are you using?

I assumed if you have a Neptune Apex you would have a refractometer calibrated for sea water and a reference solution to calibrate the probe.? To be honest I could never get my head round my Red Sea Refractometer it always seemed to drift. That`s why I use a calibrated conductivity meter.

Still, it will be interesting to see why Tropic Marine Bio Active is advertised as having a 10% discrepancy conductivity when freshly mixed. Probably something very simple, but would be nice to know.

 

[Tony Thompson]

Hi Randy, just realised that this original question is posted on the Randy Holmes-Farley Reef Chemistry forum. Hope I have not jumped in uninvited. I really do need to get used to these media forums. I can be a real nuisance at times, ha ha.

I have left a message for Hans-Werner Balling at Tropic Marin Germany. He is out of office at the moment so hopefully he will give us some answers after the break.

I noticed the was developer of the "Balling Method" So I have learnt something new already. It will be very interesting to see what information he can offer.

 

[Randy Holmes-Farley Verified Community Expert]

Hi Randy, just realised that this original question is posted on the Randy Holmes-Farley Reef Chemistry forum. Hope I have not jumped in uninvited. I really do need to get used to these media forums. I can be a real nuisance at times, ha ha.

Everyone is welcome to post any question, comment, or answer in this forum.

 

[Gareth elliott]

Does the ec probe report the same values on the tank water in a separate vessel? Perhaps theres voltage leakage some where?