2nd Batch: Low salinity partly my own fault
2nd Batch: Low salinity partly my own fault
ESV's instructions say it's mixing to 1.0256 @ 77 degrees. But in my first batch I had to add an additional 1 cup to 5 cups, 2 tsp called for in the mix instructions to bring my water a little above 1.025. It initially mixed to around 1.021.
Yesterday I mixed up my<sup></sup> 2nd batch, and it too mixed to about 1.021. ESV's instructions "“ see my 2nd post "“ clearly states "œTest and adjust salinity if necessary" after the mixing is complete. So wondering if this was something that they considered "œnormal" I gave ESV a call, and spoke to two very nice, VERY helpful gentlemen "“ Rich and Bob. They indicated that what I was experiencing was DEFINITELY not normal, and that following their instructions my salt should mix to something very close to their stated levels.
Realizing something was wrong, I began the process of questioning everything. My initial RO/DI volume, the accuracy of the measuring spoons. The accuracy of the ESV measuring cup. You name it.
I did a massively, painstakingly detailed physical measurement of my mixing container. Where I had previously calculated its volume (when full of RO/DI) to be 16.79 gallons, I found it to be closer to 17.04. That means I was starting with 1/4 gallon more than I was mixing for. That's about a 1.5% error. Not much. Material, but I something else was wrong.
Then I used my gram scale to weight ESV's 250ml measuring cup full of water. It weighed exactly 250.0 grams. Perfect. That is a strong indication that my scale is accurate, and so is ESV's cup. So that's not it.
Then I weighed a cup of ESV's salt, measuring the cup out with ESV's supplied measuring cup. It weighed 299 grams. By ESV's calculation it should be 302 grams. OK. Off by 3 grams. Meaning that in using their measuring cup, I was providing 1% too little salt.
So far I'd figured out reasons for my salt mix being 2.5% too low. But my mixing was coming out more lit 20% too low. Something else was wrong. And then I found it"¦ a REAL problem.
When I mix salt, first I always calibrate my refractometer with Pinpoint 53.0 Calibration Fluid. Then I test my salt, and then I test the calibration fluid again. If the final test does not show the calibration fluid at 35 ppt, I recalibrate and start over. I'm a real stickler for making sure I've got a good reading. I'd been using this particular bottle of calibration fluit since I started my tank about year ago. And I've got two spare bottles too. So I ripped the plastic baggie off a spare bottle (it was shipped in the airtight plastic bag), and took a reading"¦
WOW!
It was WAY LOW! So I tested the other spare bottle. It too was way low. Wow. There was only one conclusion "“ over time, my calibration solution has been evaporating, increasing the salinity of the solution. Recalibrating with the newly opened bottles, I found the old bottle to be causing me to take readings about 0.002 sg too low. Uh oh.
So when I thought the ESV was mixing to 2.021, it was actually mixing to 2.023!
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Well, that closes the gap. I still had to add 1/2 cup additional salt to get the mix up to 1.025 today. So something else is still wrong. But I've cut the error in half.
And I learned that I've got to start storing my calibration fluid in air tight baggies. Lean something every day.
But my bigger problem is my tank. Realizing that I've been using bad calibration solution, I was shocked to find that my tank is over 1.027, pushing 1.028. And it looks great! Go figure. And I'm lucky I figured this one out. Eventually I'd have killed everything, and would have been scratching my head trying to figure out why.