salinity question

Supertanker · Mar 31, 2019

I'm currently cycling my 125ga tank, no livestock. My apex says my salinity is 35.5 (I assume this is ppt, it doesn't have units). When I check with my Milwaukee refractometer I get 34ppt, and an SG of 1.026. I think I'm where I should be...please recommend the ideals. I plan on being a softie tank + a few easy fish and a clam for a year or more until I learn, then I may move to LPS. I realize SG is useless as it varies with temperature, and also that measuring devices differ a bit. But any suggestions are appreciated.
Also, just from a protocol standpoint, I started this thread new without looking if others had asked the same question in a different thread. What's the best way to get such a question answered...new thread or ask in someone else's? Isn't the latter "hijacking"?

afuel · Mar 31, 2019

I would trust the Milwaukee and use the Apex just to watch for any big changes

IslandLifeReef · Mar 31, 2019

I agree with @afuel and trust the Milwaukee reading and use the Apex as an alert to larger changes.

Mastiffsrule · Mar 31, 2019

You can always start a thread to ask questions. If you have a question relevant to a thread you are reading could ask as well. We are all here to learn or teach.

Do you have an ATO to keep water level constant?

eggplantparrot · Mar 31, 2019

a refractometer with calibration fluid is your best friend

Ruben's Reef · Mar 31, 2019

Hi @Supertanker. 1.025 or 1.026 is a good salinity especially if you will add some corals in the near future. I also have a Milwaukee digital refractometer and I keep my salinity at 1.026 but I have a few corals. Like @Mastiffsrule said an ATO is a must to keep a salinity stable. Water evaporate but not the salt so if the water is not replaced constantly you will see a salinity change.

Marco S · Mar 31, 2019

Just be glad your Apex is fairly close to what you get with the refractometer. Mine says 31.2 Ppt when my refractometer says 35 Ppt. I started a thread and got a lot of responses that it is normal for the Apex Salinity probe to be off and to trust my refractometer so that's what I am doing. I even tried to manually calibrate my Apex probe and went back to automatic and tried temperature factor in the advanced settings and it consistently stays at 31.2 Ppt so I am using the 31.2 Ppt as if it is 35 Ppt and will make sure it stays at that level.

The good news it that the other probes seem to be very accurate so I'm not too upset.