Terrible Advice Tuesdays (T.A.Tues): If your saltwater tank’s salinity level is under 1.024 specific gravity (32 ppt), then your corals will die.
The rest of the story: Corals are less tolerant of lower salinity levels than fish and most corals will survive with levels as low as 1.020 (26.6 ppt). Granted the corals likely won’t be happy – they may turn brown or bleach – they can survive.
Recommended salinity levels for a reef tank are 1.024 – 1.025 (32 – 33 ppt) and if you are slightly below or above that level (1.022 – 1.027), your tank will be just fine. Of course if your levels are out of the 1.024 – 1.025 range, I do recommend you bring them back in check.
If your salinity level is low, I recommend doing a series of water changes with higher salinity water to bring your salinity back to the recommended levels. For example, if my tank’s salinity was 1.022, then I would do my weekly 5% water changes with saltwater with a salinity level of 1.030. After each water change, I would test the salinity of my tank’s salinity to monitor the salinity changes.
If your salinity level is high, doing water changes with lower salinity water or replacing small amounts of your tank’s volume with straight RODI water will lower your salinity levels.
I DO NOT recommend you mix salt directly into your tank, or even into a high flow area of your sump! Salt crystals can burn corals or fish! Also, chemical reactions are happening as the salt and other chemicals are dissolving in water and you don’t want your livestock in the direct path of these reactions.
Mix your salt in a bucket or mixing container, then do your water change.Browse the Store! Questions?