Difficulties measuring salt level accurately

[the_chef_pierre]

I seem to be having difficulties finding the correct level of salt in my aquarium. I have a vertex refractometer I was given, and have calibrated it to 0 using RODI water. After this, when I measure my salt level it's reading around 1.025. If I use my Deepsix Hydrometer it tends to read around the same (but I find my measurements are not always accurate using this).

Recently, I purchased some Brightwell Aquarium Reagents refractometer calibration standard thinking that this would help truly accurately calibrate my refractometer. The directions for this solution ask to calibrate to 35 ppt using it and then measure your water after, yet when I do this my readings now read significantly lower salt levels (arund 1.021-1.022). Should I assume that this is the most accurate and increase my salt concentration in my water or is it better to just stick with my original calibration using the RODI water since this gives me similar reading when using my hydrometer? Any advice

 

[B7Joe]

Mine specifically indicates in the directions that it must be calibrated using a 35ppt solution and not RODI. Maybe someone with experience with your unit will chime in.

 

[the_chef_pierre]

Hmm, maybe youre right. It could vary depending on refractometer model. The manual for mine does say to calibrate with RODI water so maybe its different for each model

 

[vetteguy53081]

I would take refractometer and a water sample to a trusted LFS and have them test and verify your readings and see how they compare with yours and also see if your refractometer matches with readings

 

[the_chef_pierre]

True. I'll see if the lfs near me does that. I feel that they dont care that much and are actually just simply trying to push the sales of their products, which is why I love asking all you guys questions on here because everyone here is way more helpful and knowledged than my lfs

 

[vetteguy53081]

True. I'll see if the lfs near me does that. I feel that they dont care that much and are actually just simply trying to push the sales of their products, which is why I love asking all you guys questions on here because everyone here is way more helpful and knowledged than my lfs

Sorry to say but I'd seek s new LFS. I drive over an hour to one that treats me right and has earned my trust .

 

[fcmatt]

I will be blunt. Those hydrometers that are plastic with a swing arm are junk. Yes some are accurate and if you are unlucky it is not. They are meant for fish tanks in my opinion where being close enough is good enough. Cheap. Starter stuff.

Calibrating with rodi is not as good as a 35 ppt solution. The solution is always an improvement.

A refractometer with a brand new solution is your most accurate tool right now.

Buy another solution from a diff manufacturer. Use 2 to calibrate.

Then trust it.

Solutions need to have cap on tight all the time. Open, use, cap back on quick. Dont leave it sitting out open for 20 minutes each time you use it. Replace every 1 to 2 years.

 

[the_chef_pierre]

I totally agree. I wish we had better places here in Canada, but there isn't that many. The smaller ones either sell garbage products with really dirty tanks or the larger one just overstocks their fish and is simply pushing products down everyones throats. I guess theyre trying to run their business, but youre right that that is definitely not the best way to keep returning customers

 

[the_chef_pierre]

What hydrometers would you guys recommend, because so far i've only used the swing arm prism type and the plastic garbagy one that you sink in the water to fill it. Definitely preferring the prism type one so far, but maybe it is an issue with the one i have or even the solution. Ill try to see if my lfs can actually check my water without them giving me a hard time about it

 

[legrunt]

I had a similar experience. Calibrated to 0 using distilled water. Even took it to the lfs and calibrated it to their tank water at 1.025. Then one day, bought the same calibration liquid as you and found out my tank was actually at 1.020. way too low. Got fed up with hard to read and inaccurate refractometers and purchased the hanna conductive meter.

 

[birdy123]

The Hanna checker is a wonderful piece of kit but as has been said as only as accurate as it’s calibration.
Also the sample that you use and what you use to take the sample has to be clean as this can upset the reading. The swing arm type hygrometer in my experience becomes inaccurate as soon as the salt residue starts to build up. A good quality refractometer cleaned, calibrated using a clean sample is a good compromise.

 

[the_chef_pierre]

oh sorry, i got confused. by swing arm i thought you meant the refractometer and were refering to the plastic part that swings over the lens. But i agree, the refractometer is much better. I just have to solve whether it should be calibrated with RODI water or calibration liquid. Just checked the manual for it and it says to use distilled water to calibrate to 0, so maybe it has something to do with needing to be calibrated to 0 using just RODI water. I may check doing that and then using the calibration solution to see if it reads 35 ppt again, but maybe its just an issue with the solution i just bought. Could have been sitting on their shelves for awhile or something

 

[tstar]

In my limited experience, the temperature of the sample/calibration fluids has to be the same. I draw my tank sample and leave it out on the counter with the 35 ppt calibration fluid for several minutes. Then calibrate, clean the refractometer and read the sample of the DT.

Tim

 

[legrunt]

The Hanna checker is a wonderful piece of kit but as has been said as only as accurate as it’s calibration.
Also the sample that you use and what you use to take the sample has to be clean as this can upset the reading. The swing arm type hygrometer in my experience becomes inaccurate as soon as the salt residue starts to build up. A good quality refractometer cleaned, calibrated using a clean sample is a good compromise.

It comes with 4 sachets of calibration fluid and it's a more or less idiot proof method of calibration.

oh sorry, i got confused. by swing arm i thought you meant the refractometer and were refering to the plastic part that swings over the lens. But i agree, the refractometer is much better. I just have to solve whether it should be calibrated with RODI water or calibration liquid. Just checked the manual for it and it says to use distilled water to calibrate to 0, so maybe it has something to do with needing to be calibrated to 0 using just RODI water. I may check doing that and then using the calibration solution to see if it reads 35 ppt again, but maybe its just an issue with the solution i just bought. Could have been sitting on their shelves for awhile or something

Calibrating the instrument closest to where you would be using it most of the time would be the best practice, regardless of what it says on the manual. I calibrated mine at 0 with distilled water. Still ended up severely under reading my tank.

 

[homer1475]

Never, never calibrate a refractometer with RO/DI. You need 35PPT calibration fluid.

If you calibrate to 0, and you test 35PPT(1.026SG), it will be off because of the linear measurement of a refractometer.

Also someone said you have to wait a few minutes so temps stabilize. Also mot true if your kit says ATC on it(which means Automatic Temprature Compensation), it has already has a temp curve built into it.

If your calibrated refractometer(using 35PPT solution) is telling you your tank is closer to 1.020, then you calibrate with RO/DI and it reads 1.025, which do you think you should believe?

 

[Waters]

I feel your pain...I have even found calibration solutions to be off from one bottle to the next which complicates things even further. I use a refractometer and a digital Milwaukee, and I am still not sure my number is exact. As long as you are close and you aren't seeing swings, stick with whatever you are reading (assuming the tank looks good).

 

[mike550]

I’ve been using a Hanna checker since day one. It’s easy to use, adjusts for temp, and pretty much foolproof. I calibrate once a month (which is also easy) and run maybe 15-20 tests / month.

 

[BeejReef]

Just adding to chorus.. by the book, calibrating ur refracto w 35ppt solution is the "best."
Exactly what I do as well. Still, whenever there's uncertainty with THE most important parameter, I'd seek to doublecheck it.

 

[Tuan’s Reef]

This is personally my favorite tool in the hobby

 

[Super Fly]

I seem to be having difficulties finding the correct level of salt in my aquarium. I have a vertex refractometer I was given, and have calibrated it to 0 using RODI water. After this, when I measure my salt level it's reading around 1.025. If I use my Deepsix Hydrometer it tends to read around the same (but I find my measurements are not always accurate using this).

Recently, I purchased some Brightwell Aquarium Reagents refractometer calibration standard thinking that this would help truly accurately calibrate my refractometer. The directions for this solution ask to calibrate to 35 ppt using it and then measure your water after, yet when I do this my readings now read significantly lower salt levels (arund 1.021-1.022). Should I assume that this is the most accurate and increase my salt concentration in my water or is it better to just stick with my original calibration using the RODI water since this gives me similar reading when using my hydrometer? Any advice

I calibrate refractometer before each use with calibration fluid. Also please note that the temp of refractometer will affect the reading so it should be close to tank water temp and not 10-20 degrees cooler. Which is why I always leave refractometer on 1F of house vs basement where tank is located. On very cold days even leaving refractometer in basement for 30 mins will affect my reading, in which case I have to warm it up using a space heater.