Salinity close to 40ppm, new tank cylcing.

[JustJax]

I am cycling my new waterbox 20 cube. I got ocean water from my LFS and I am getting readings of 40ppt or 1.030. I know this is a bit high. I have a refractometer I got off of amazon for $20 and used the calibration fluid. Am I possibly doing something wrong?

 

[redfishbluefish]

Is it an ATC (Automatic Temperature Compensation) refractometer. Cold water results in higher salinity numbers.

 

[JustJax]

Is it an ATC (Automatic Temperature Compensation) refractometer. Cold water results in higher salinity numbers.

Yes it is, temp is about 80 F. Think that is the issue?

 

[reefinatl]

Am I possibly doing something wrong?

Always possible, do you have a swing arm tester as well by chance? Could check one against the other make sure they are close.

Temperature has an affect of sg, but not much if you are within 10 degrees of the calibration temp it'll be only .001 off.

1.030 is high but nothing to worry about in a panicked way, especially during cycle.

Go get an RO system and do a few WCs with 1.026 that you mixed yourself over the next month and all will be fine.
Welcome to reefing

 

[Azedenkae]

I am cycling my new waterbox 20 cube. I got ocean water from my LFS and I am getting readings of 40ppt or 1.030. I know this is a bit high. I have a refractometer I got off of amazon for $20 and used the calibration fluid. Am I possibly doing something wrong?

Might just be something during your water mixing stage and you added a bit too much salt. Presuming there was no issues with the refractometer, and calibrating it, of course.

If you want to get it down to 35 ppt (the usually suggested concentration), then just do a 12.5% water change with fresh water.

 

[davidcalgary29]

From someone who's definitely been there:

-is the refractometer for salinity, or alcohol? I of course got the one for alcohol.

-how often do you calibrate the refractometer? I check mine with 35ppt fluid about once per week

-if the readings are true, then use some RODI water to lower salinity. If you can't find any, just get distilled water from the supermarket and dilute slowwwly. Not perfect, but it'll do in a pinch.