Sleepydoc
Valuable Member
- Joined
- Apr 10, 2017
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- 1,423
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- Location
- Minneapolis, MN
- What state or country do you live in
- Minnesota
As mentioned above, the Apex salinity probe is notoriously prone to interference, either from wires running close to it or from micro bubbles. Routing the wire separately and mounting it at a 45º angle can help. FWIW, I've heard of similar issues with similar probes from other companies. Continuously measuring minute changes in conductivity in a reef tank over a long period is actually more difficult than one would think.
I spent a bunch of time messing with my salinity probe when I first got my Apex, then forgot about it. A few months ago I actually looked at the graph and realized it's actually tracking pretty well. It's not accurate, but I haven't calibrated it in 18 months, I can't really complain about that. Regardless, I don't consider it reliable or accurate enough to truly rely on without another measurement. I got a Hanna salinity probe and have found it much more accurate and reliable.
What I realized is that of all the probes that come with the Apex, the salinity probe is probably the least important. You can't use it for your ATO; a float valve or optical sensor is far more accurate for that. My setup is a 120 display + 40b sump with a 10G ATO reservoir. Even if the entire reservoir got dumped into my tank, the sump wouldn't overflow and the total change in salinity would be less than 0.002 (i.e. it would drop from 1.026 to about 1.0241.) Not desirable, but far from catastrophic and likely not enough to cause significant issues. Other setups may be different, but for me the combination of the lack of reliability and the lack of true need to follow salinity continuously means it isn't something I worry about.
I spent a bunch of time messing with my salinity probe when I first got my Apex, then forgot about it. A few months ago I actually looked at the graph and realized it's actually tracking pretty well. It's not accurate, but I haven't calibrated it in 18 months, I can't really complain about that. Regardless, I don't consider it reliable or accurate enough to truly rely on without another measurement. I got a Hanna salinity probe and have found it much more accurate and reliable.
What I realized is that of all the probes that come with the Apex, the salinity probe is probably the least important. You can't use it for your ATO; a float valve or optical sensor is far more accurate for that. My setup is a 120 display + 40b sump with a 10G ATO reservoir. Even if the entire reservoir got dumped into my tank, the sump wouldn't overflow and the total change in salinity would be less than 0.002 (i.e. it would drop from 1.026 to about 1.0241.) Not desirable, but far from catastrophic and likely not enough to cause significant issues. Other setups may be different, but for me the combination of the lack of reliability and the lack of true need to follow salinity continuously means it isn't something I worry about.
