Another Victim of Refractometer...

[hilde123]

I have been naive for the last 20 years thinking my refractometer was a reliable tool to check salinity. I just did my 3rd Fauna Marin water analysis test over the last year and I guess this one was more comprehensive then the one I typically do and checked basic values which included salinity. To my great surprise it indicates my salinity is 30 ppt and I have checked monthly for the past several years and it is rock solid at 35 ppt from refractometer. In fact I tested all my values the day I made the ICP sample for comparison. Since I use ATO and calc reactor I rarely have to make any adjustments to meet ideal salinity. With a little internet research I see the refractometer and using RO/DI to calibrate isn't really the proper way. I'm going to make up a known solution of 35 ppt tonight and check but I'm sure the ICP test is accurate... In doing my reading it looks like Hanna pen is way to go so I went ahead and purchased one of those for future use. My question is how slowly should I raise. Calculator says I need to add 9.5 pounds to get to 35 ppt (~200 gallon system). Also, how much should I expect my alk and calcium levels to increase in raising salinity noting they are already on the high side. Also, I should note tank is full of SPS, LPS, anemones, and clams. Attached is the water analysis.

 

[exnisstech]

Just a heads up in the Hanna. I've had two and they both read 0.002 low when calibrated with Hanna solution. I've seen others report the same. Others say they work fine so.... If you want something affordable and reliable never needing calibration maybe look at the TM hydrometer. I use one and use water tested with it to calibrate my refractometers.

 

[BryanM]

This is the way: TM hydrometer.