Adding water.

[Chef Steve]

This is just a general question about adding water to reef tanks. If ur salt is in desired range, let's say 1.025-1.026, and ur water is about to be irritating and drop below the rim. (Gerwin cringes at this thought, as read from previous posts). Would it be better to add fresh ro water And drop salinity to 1.024 or make fresh salt water and keep salinity in desired range?

[Dragont]

Wut I would do is add more saltwater but not fresh mixed to desired level. After each weekly water change I go ahead and rinse my container out and mix new saltwater for the next week. Throw in a powerhead and let it run for a week before I use it. I forget wut chemical it is that newly mixed salt releases but I know it's not good. Ammonia maybe? I forget where I read that from. Maybe this is the reason why gerwin doesn't want u using fresh saltwater.
Besides I don't see anything wrong with 1.024. Doesn't seem like much of a extreme drop in salinity. Should be ok eiher way.

[Scott Allen]

As evaporation happens you only lose freshwater because the salt doesn't evaporate. So if you are topping off evaporation, you want to use ro/di. You're salinity increases as the water level drops. So by adding more ro/di you are bringing the salinty down by diluting the saltwater back to the original level.

[Scott Allen]

On the other hand, if you're tank's water level is low due to using water for acclimation or some other reason then replace that with new salt water mixed to your desired overall salinity. If over time, your salinity levels have dropped due to salt creep you can bring the salinity up with slightly more salty water for top off, just go slow and don't move more than .001 sg in a single day.

[Gerwin]

well said

[Chef Steve]

Understood. I dnt typically always add salt water just add water that will keep my salinity in same area. Sometime fresh to bring down and sometimes salty to keep the same. My skimmer pulls water and lowers levels so really that is only time I use salt water or as mentioned for acclimation. As for freshly mixed saltwater being bad, is there any truth to this? I normally have mixed ahead of time, just want to make sure. Everything seems fine thus far. Including the duncan that just popped five new heads lol

[Scott Allen]

Understood. I dnt typically always add salt water just add water that will keep my salinity in same area. Sometime fresh to bring down and sometimes salty to keep the same. My skimmer pulls water and lowers levels so really that is only time I use salt water or as mentioned for acclimation. As for freshly mixed saltwater being bad, is there any truth to this? I normally have mixed ahead of time, just want to make sure. Everything seems fine thus far. Including the duncan that just popped five new heads lol

It's a very minor issue. You most likely won't ever see the effect of using new saltwater. I have read somewhere about the potential for precipitation of some unwanted something. But the average hobbyist doesn't need to worry about it. Just make sure it's well mixed and no salt is still visible.