High Salinity or Defective Refractometer

[dragonfisher33]

Got my first refractometer from BRS this week just in time for Christmas and calibrated to the 35PPT as indicated on the instruction. As a sanity check, i checked my RODI water, which turns out to be 0PPT. Next i checked my actual tank water. the reading is 40PPT. so i added about 3 gallons of RODI water slowly into my tank. Checked the refractometer reading again. Still 40PPT. Add 2 more gallons of RODI, STILL 40PPT. Scratching my head a little and checked the calibration fluid reading again. Still at 35PPT.

So, either this new refractometer is defective or my tank for some reason has high salinity.

Any Idea?

If the refractometer is reading the calibration fluid and the RODI water correctly, can i assume that the refractometer is functional?

 

[Trex]

What size tank?

When you calibrated it, you looked at a light source. When you tested your tank's water, did you use the same light source when you looked into the refrac?

 

[dragonfisher33]

What size tank?

When you calibrated it, you looked at a light source. When you tested your tank's water, did you use the same light source when you looked into the refrac?

~40 gallon of water. same light source

 

[Trex]

Hmm.

When you added the water, where did you add it ?
Where did you take the water out to measure it?
How much time elapsed between adding the water and the re-measure?

 

[Greenstreet.1]

High salinity

 

[dragonfisher33]

Hmm.

When you added the water, where did you add it ?
Where did you take the water out to measure it?
How much time elapsed between adding the water and the re-measure?

i added the water directly into the tank because I don't have a sump.

the tank water is measured 10min after the addition of the rodi water

 

[dragonfisher33]

the measurements did not change between yesterday when ni rodi water was added and when around 4 gallon of rodi water was added. just checked the water reading again and still at 40PPT

 

[Greenstreet.1]

Try calibrate it with rodi water to zero then test the tank and see what you get

 

[dragonfisher33]

well, the instructions that came with the BRS refractometer says not to calibrate to rodi water

 

[Greenstreet.1]

I understand that but you are trying to find out if it has a problem correct ? so if your tank is 40ppt you should get 40 when you use rodi to calibrate then calibrate it back with the solution

 

[Greenstreet.1]

I use the same one from brs

 

[DMan]

try mixing up a small batch of fresh salt water and use less salt so you know the salinity is low. check and see what the refractometer says. also what were you measuring with before.

 

[dragonfisher33]

I understand that but you are trying to find out if it has a problem correct ? so if your tank is 40ppt you should get 40 when you use rodi to calibrate then calibrate it back with the solution

understood. let me try that out

 

[dragonfisher33]

so I calibrate the refractometer using rodi water and did a reading on the tank water: 41ppt

 

[Greenstreet.1]

so I calibrate the refractometer using rodi water and did a reading on the tank water: 41ppt

Well now you know that your salt is high

 

[saltyhog]

Well now you know that your salt is high

Yep it's amazing how much RO/DI it takes to lower salinity much even in a tank that size.

 

[Greenstreet.1]

Yes it takes a lot