Problem found! Salinity @ 31.5 ppt

Nerdist Aquarist

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Jul 12, 2019
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For the last 6 months I've been experiencing slow SPS and Zoa degradation and some deaths. Not once have I thought it I was low salinity. Every water change I calibrate my refractometer with calibration fluid, and also compare against a hydrometer. Somehow both were way off! I do have a Hanna salinity checker but never used it more than once. Why, because it was giving a low reading , lol. I've done 2 recent ICP tests and they pretty much match the Hanna, so all this time the Hanna was right when I thought it was defective!

My Salinity is now at 31.5 ppt, I'm actually impressed that corals are not deteriorating faster than they are. This has been going on for more than 8 months looking back at the salinity reading from a previous ICP test.

So now I start the process to slowly raise it to 35. I've been dosing sodium hydroxide for almost a year now. I was really close to stopping it, thinking it must have been some contaminant. I'm still puzzled how the refractometer and hydrometer could be so wrong at the same time.

Here's a couple pics of recent coral fatalities.

IMG_20220705_183019.jpg IMG_20220705_182852.jpg
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