Raised my salinity too high

[jasonrusso]

So don't judge me, haha. I have never calibrated my refractometer with solution, I always set zero with RODI. The tank was thriving a couple months ago, but I haven't been too happy with it recently. I was doing a full workup this weekend and I noticed that my reef tank salinity had dropped to 30ppt. I figured that was the reason, because I was having an issue with my skimmer overflowing. The ATO lowered the salinity. It all made sense. Over the next 2 days, I raised the salt to 35ppt on my refractometer. At the same time, I ordered some calibration fluid on Amazon. When I checked it, I was surprised to see the reading at 30ppt. I did it twice to confirm and adjusted it to 35ppt. Of course, now my tank is at 40ppt!! Over the next couple days, I'll scoop some water out and let the ATO fill it up until I can get it back to 35ppt.

From what I can read, average PPT is 35ppt, but it ranges from 32ppt to 38ppt. So I don't think that 40ppt is THAT bad, it's not good but I think if I get it back down in a few days it isn't a death sentence.

Any other thoughts?

This is the fluid I bought, I figured that you can't screw this up too bad. It gets good reviews.

 

[Terri Caton]

Calibrate your refractometer Every time before you use it! They tend not to stay put at the right number.

Lowering the salinity slowly is the only thing you can do at this point. If nothing is looking stressed don't worry. If things begin to look stressed I'd do a larger WC to get it down quicker.

 

[NormanB]

I use that calibration fluid and it works well for me.

i think more frequent calibration checks are good till you see how stable for refractometer is then check and recalibrate as needed.

 

[Phildago]

Why would calibration fluid be any better than rodi? Presuming the rodi is 0 tds

 

[jasonrusso]

Why would calibration fluid be any better than rodi? Presuming the rodi is 0 tds

Right now, my Refractometer is reading 2-3 with rodi.

From what I can research, they are designed to be accurate in the 30ppt range. They lose their accuracy at the outer ends of the range.

 

[NormanB]

I am certainly no expert when it comes to calibration. My thought is to test at or near the value of the sample. In our case around 35ppt...whereas rodi is at 0 ppt much further from the target. Granted I don't know how linear the refractory is and surely varies by manufacturers and to some degree within a model. So, perhaps checking by a two point calibration would be better?

If I remember correctly, Randy has an excellent writeup on refractory calibration.

just my 0.02