Sudden drop in salinity

[capdippe]

Any ideas on a sudden drop in salinity? Checked it last night and got 1.023 after a water change. Checked it this morning and got 1.025. Checked it at 3pm and got 1.024, then again at 7:30 and got 1.020. This was after a feeding of oyster feast, mag and calc dosing, Matt.

 

[lvsuckerfish]

what are you testing with?

 

[tat2z_21]

Temperature will increase and decrease salinity. What is your temperature during this slight swing of salinity. I do believe that there are several things that will effect your salinity. However if you are using a float to check your salinity that could also be another contributer.

 

[capdippe]

I'm using a refractometer calibrated with RO/DI water at 68F. The tank has a cheep chiller that keeps the tank at 76F-78F. I checked the salinity at 10:30PM and it's 1.024. I can't figure out what caused the sudden change other than maybe my refractometer was hot from being in the garage where I mix salt water.

 

[returnofsid]

Do you have an auto top off that could be topping off too much fresh water, into the tank? Or a possible leak, where saltwater is leaking, and being replaced with fresh water, through an ATO?

 

[capdippe]

No auto top of unit, but that is something I'd never thought of. Another item to put down on the list of "things to watch out for".

 

[Faciosity]

You say it happened after a water change, if the water you put in was a different salinity as the water already in the tank, it could have still been mixing and adjusting.

 

[capdippe]

True, but the drop was 14 hours after the change; and I mixed the water for for about 4 hours before it went into the tank.

 

[capdippe]

It seems to be fine now, I think I'll need to give more time between dosings and let the tank settle.

 

[returnofsid]

I would suggest that your refractometer may not be keeping it's calibration.

 

[Kurt_Nelson]

And you also want to calibrate it using 53mS calibration fluid like this:

http://www.bulkreefsupply.com/store/pinpointr-salinity-calibration-fluid.html

Refractometers are not necessarily linear, and calibrating with RO/DI just sets it at 1.000. Better to calibrate with something closer to what you're testing.

 

[blk822822]

If you take your refractometer to Barrier reef they will check it for you. Brie calibrated mine for me. I keep forgetting to buy some calibration fluid when I go up there. And some refractometers will read differently due to temp. When you test put the water on the tester and wait a few for the temp to drop to room temp and check. Thats what I have read about some testers.

 

[burning2nd]

it not suppose to be calibrated with rodi water.

 

[thatguy559]

if anything calibrate it with distilled water. thats how i calibrated mine and its dead on. tested against three other refractomers

also as stated above temp has a lot to do with salitinty, mix your water for about 24 hours make sure the water is warmed up or room temperature before mixing in the salt it disolves and mixes easier.

 

[tat2z_21]

I calibrate mine with yak urine. Works like a champ every time. Just kidding. But does temp effect salinity. I know on the grander scale (the world) the places where it hot the salinity is higher on average then the other areas of the world.

 

[capdippe]

Thanks guys, I reread the instructions and sure enough I need to use distilled water. I'll get it checked this weekend. Thanks!

 

[DonW]

If your worried about it being absolutly perfect then you need cal fluid. RODI water is fine for most of our use. Temp will affect a refract especially if stored in a hot room. Most have temp compensation but will not work well if they get to hot. They can only compensate so much.

Don