lower salinity issues

[Randy Holmes-Farley Verified Community Expert]

I had thought the distilled water we buy at the store was a steam distillation, and very pure. Do you not recommend using distilled water for those that don't have an RODI? I've used it at times myself without any issues I knew about. Thank you in advance!

Most large stills likely use stainless steel for condensation, and the metals released will be acceptable in reef use. But I think it is not correct to say it must always be ok since almost no analyses of distilled water for copper have been published.

Here’s one that I found a while ago:

https://www.reef2reef.com/threads/r-o-vs-distilled-water.729787/page-2#post-9483096

 

[Fish Fan]

Most large stills likely use stainless steel for condensation, and the metals released will be acceptable in reef use. But I think it is not correct to say it must always be ok since almost no analyses of distilled water for copper have been published.

Here’s one that I found a while ago:

https://www.reef2reef.com/threads/r-o-vs-distilled-water.729787/page-2#post-9483096

Thank you for your reply!

 

[Uncle99]

Related question from new tanker: I have a 55gal tank on a cannister filter, initial water loaded in 2 months ago, first two fish 1 month ago and nothing since. Parameters are stable. Open screen-covered top, low lights for now. Evaporating about 1/2 gal/day.

I was told the salt doesn’t evaporate so just top off with RODI, which I do. But I’ve noticed twice now my salinity has dropped from 34ppt to 32ppt and I’ve had to add saltwater / water change to bring it up.

Is this normal? What causes salinity to go down? Just trying to learn what’s normal and what’s a problem.
Thanks!

Use an ATO to ensure accuracy in salinity due to evaporation

 

[dippy-bird]

Related question from new tanker: I have a 55gal tank on a cannister filter, initial water loaded in 2 months ago, first two fish 1 month ago and nothing since. Parameters are stable. Open screen-covered top, low lights for now. Evaporating about 1/2 gal/day.

I was told the salt doesn’t evaporate so just top off with RODI, which I do. But I’ve noticed twice now my salinity has dropped from 34ppt to 32ppt and I’ve had to add saltwater / water change to bring it up.

Is this normal? What causes salinity to go down? Just trying to learn what’s normal and what’s a problem.
Thanks!

(Maybe not really relevant for a 55gal tank) -
If you are running a skimmer and you are running it wet you export a significant amount of saltwater out of the tank, with a ATO you refill it with RODI water and your salinity can drop over time

 

[MNscoe]

Good questions. I haven’t been that precise so far. I add 0.25 - 0.5 gallons of RODI each morning. I have a spot on the rim I kinda eyeball for consistent water level.

I measure salinity before adding new RODI. Using an Aqualife Pro.

Well, dangnabbit, turns out my salinity tester was going out of calibration. I went to do a water change and was adding salt, and when I added a bit more salt my test readings went DOWN. As a newbie, that was the first time I realized you need to calibrate (and monitor the calibration of) the Aqualife Pro tester! Dang.

Therefore when I thought my tank salinity was going down, and I starting using saltwater to top it off, I was actually increasing salinity to about 38ppm. Oops! Fixed now.