Coral Reef Forum

Hyposalinity:

Bringing the salt content down to a range of 1.010 to 1.008 (specific gravity) to be effective and truly considered as such.

All marine creatures require freshwater just as we do to survive, they just process it differently. Since their bodies are less salty than the water surrounding them, to prevent the loss of needed freshwater they take in seawater, process it to eliminate the salt molecules, and then retain the freshwater to maintain a balance with nature. When the salinity of seawater is lowered, or hyposalinity is applied, it results in a lowering of the osmotic pressure of the water at the same time, thus the related name Osmotic Shock Therapy (OST). Fish and a few other sea creatures can withstand and adjust to this change in pressure, but protozoan (Cryptocaryon/White Spot Disease, and Brooklynella/Clownfish Disease), dinoflagellate (Oodinium/Velvet or Coral Fish Disease), and flat worm (Black Spot Disease) ich organisms cannot. Reduce this necessary pressure, particularly rapidly, and they literally explode! Although delicate corals and invertebrates may not immediately rupture as ich parasites do, these too are marine animals that cannot tolerate exposure to low osmotic pressure, resulting in a rather quick death.

When to use Hyposalinity:

• While treating fish in a QT, lowering the salinity can help prevent newborn ich organisms that might be released from mature cysts from reinfecting the fish during the quarantine period.

• As a preventative measure, when new fish are brought home and placed in a QT for several weeks of observation before introducing them into the main aquarium.

• Hyposalinity should NEVER be used in a reef system, as it will kill corals and all types of delicate invertebrates. Since most people in all likelihood will not want to disturb these animals, not to mention have to hassle with removing them and set up another tank to put them in, the easiest thing to do for a reef tank is to leave it devoid of all fish for at least 4 weeks and allow the ich to run its life cycle and die off.