Specific gravity Problem

[taat2d]

For some reason my Specific has gone UP for a second time within a few days. Why would this be happening? When I add top off water to my tank it's RODI water and it UNSALTED.The reading has gone from 1.22 up to 1.30. Can someone please tell me why this is happening?

 

[TimberTDI]

Are you dosing anything?

 

[taat2d]

No Dosing. Ammo is 0, nitrates is 0, nitrates is 0. Tank is running 3 weeks. And the only water I've been adding is RODI top of water.UNSALTED.

 

[NYreefNoob]

gravity

what are you using to measure salinity ? this could be the problem

 

[taat2d]

what are you using to measure salinity ? this could be the problem

A Deep Six Hydrometer. Made by Coralife I believe.

 

[digitalreefer]

Did you recently do a water change?

If you're using one of those plastic hydrometers, make sure you rinse it well with freshwater before using it. Then toss it and get a refractometer.

 

[taat2d]

Did you recently do a water change?

If you're using one of those plastic hydrometers, make sure you rinse it well with freshwater before using it. Then toss it and get a refractometer.

Whats the diference between a hydrometer and a refractometer? Got a pic of the latter?

 

[digitalreefer]

A refractometer is much more accurate. The hydrometer you're using is probably not giving you a very accurate reading.

http://www.marinedepot.com/aquarium...ters_captive_purity_refractometer.asp?CartId=

 

[NYreefNoob]

salinity

id say 99% sure it isnt changing like you think, throw that meter away and buy a refractometer. i used the same thing for 3 months and new something wasnt right. so i bought a refrac and there was a differance from it and the other of refrac 1.23 coralife was reading 1.26 tested refrac on another tank to make sure it was right and it was. if someone is near you and they have a refrac id ask them to stop by and test it to be sure

 

[taat2d]

id say 99% sure it isnt changing like you think, throw that meter away and buy a refractometer. i used the same thing for 3 months and new something wasnt right. so i bought a refrac and there was a differance from it and the other of refrac 1.23 coralife was reading 1.26 tested refrac on another tank to make sure it was right and it was. if someone is near you and they have a refrac id ask them to stop by and test it to be sure

I think you're right. I just rinsed out the hydrometer with clean tap water and tested the water again and this time I got a 1.22 reading. I need to order a refractometer I see. But why would rinsing the hydrometer with water make a difference?

 

[TimberTDI]

Because when the water that's left dries off it leaves a salt residue. What do you think happens to the salt in the hydrometer when you add water again?

 

[taat2d]

Because when the water that's left dries off it leaves a salt residue. What do you think happens to the salt in the hydrometer when you add water again?

I rinse it in clean water every time AFTER I use it though. Could it still make a difference to rinse it BEFORE too?

 

[digitalreefer]

The hydrometer can also be affected by dust, etc... always rinse before and after.

 

[Henrye]

If you're using one of those plastic hydrometers, make sure you rinse it well with freshwater before using it. Then toss it and get a refractometer.

Any air bubbles on the arm can also skew the result. There are too many variables to throw off a swing arm hydrometer, unless you calibrate it against a refractometer/salinity probe, and are rigorous in performing your measurements the same way every time, and keep the hydrometer meticulously clean of any salt buildup.

I agree, toss the hydrometer and get a refractometer. It's impossible to run a SW tank without having faith in your ability to determine the s.g./salinity of your water. Personally, I wouldn't bother rinsing the hydrometer in fresh water before tossing it, though.