Another Idiot Alert

[Mark Goode]

For the last 10 months I have used a Red Sea refractometer and an Apex conductivity probe to measure my salinity. After a bit of a shaky start when the Apex probe seemed to be away with the fairies, I found a place where it seemed happy, and the two salinity measures were broadly in agreement. Then, a week ago, around the time of my last water change, the Apex probe started pinging high salinity alerts. I checked with the refractometer, and it still said 34 - 35, so the Apex probe reading of 42 is clearly wrong. However, the refractometer has not been calibrated since I bought it in June of last year, so I went to my LFS yesterday for some calibration juice. They had none.

I ordered a cheap swinging pointer hydrometer from Amazon (a Fluval, a name I'd heard of) to do a quick check while I waited for calibration fluid. It arrived today, and after a good rinse with RODI I filled it with tank water. The pointer swung upwards, off the scale. In a panic, I set the RODI running, and wracked my brains to try to understand where the extra salt had come from. Have I been filling my ATO from the saltwater bucket? No, that was still full. Could I have put too much salt in the mix when I changed the water? It's possible, but surely not by that much?

I returned to the tank while the RODI unit did its thing and watched to see what the high salinity killed first.

Then I noticed the tiny bubble on the underside of the swinging pointer... Once that was dislodged, the needle pointed to 35ppt.

Somebody shoot me.

 

[Tamberav]

Always best not to panic and make drastic changes. Equiptment and test kits can be finicky and like you said... where would the drastic change in salt come from? Are the corals/inverts/fish all happy? yes? Trust your instincts

At least you caught it

 

[bushdoc]

“Have I been filling my ATO from the saltwater bucket?”
And there is also time proven organoleptic method. It is a bit crude and binary as it differentiates only between fresh water and saltwater.

 

[Mark Goode]

“Have I been filling my ATO from the saltwater bucket?”
And there is also time proven organoleptic method. It is a bit crude and binary as it differentiates only between fresh water and saltwater.

I'm not sticking my organ in the tank, thank you very much, there's a venomous foxface in there!

 

[snorklr]

Tropic Marin glass hydrometer and a $10 500ml plastic graduated cylinder...i like to keep things simple...of course it needs to be measured at 77 degrees and i have 3 digital thermometers that dont agree but thats another story...