help with apex salinity probe

[rschneid]

Hi, I am a noobie... So I am sure I am making mistakes. I am setting up a 75 gallon tank with sump from scratch.
I have an Apex with Salinity Probe. Out of the box it was measuring 3.2 in my tank when it was filled with R/O water. (possibly in retrospect this is part of the problem) Why is it measuring anything - shouldn't it be zero?
After adding 48 cups of reef crystals, the measurement fell first to 1.6 and then gradually rose to 2.6. So I am really confused. Shouldn't this be rising not falling as I add salt?
No I did not calibrate it. I don't have any solution but I did find on the web where I can probably make some, but before I do that I could really use a little bit of help from someone with one of these salinity probes to tell me what it should be doing.
If i put it in a glass of distilled water, should it be reading 0 or something else?
As I add salt shouldn't the reading be rising?

I have searched the web and I am not having much luck finding answers to some of these questions.

Rich S.

 

[edsbeaker]

Welcome to CR.

I have an apex, but not a salinity probe. I was looking on Bulk Reef Supplies website and they have a video on how they need to be set up. If they are not set up correctly and calibrated with a temp probe and in water that isn't moving they will not work properly, and your readings will be high, low and everywhere in between. It looks like the probes are very fussy. So, I can't answer your questions per se, but maybe this link to the BRS video can help. Good luck. I've used neptune controllers for years, and have been able to figure out most of everything, but I have to say, this video looks complicated!!!!

https://www.youtube.com/watch?v=NyC8x57E5DA#t=14