pH Control
pH is hard to control in a hyposaline solution because at this dilution, the buffer ability of the diluted saltwater is not good. Be prepared for this.
Make pH adjustments with pure baking soda (e.g., Arm & Hammer) you find in the grocery store, or better yet is sodium carbonate. Sodium carbonate can be made in the home oven. Take a pound of pure baking soda and spread it out evenly on a large cookie sheet. Put into a preheated oven to 350F. Bake it for 30 minutes. Take the sheet out of the oven, let cool to warm and put into an air-tight, clean container for use. Now the baking soda has been turned into sodium carbonate, a more potent pH + additive.
DO NOT try to control the pH with pH buffer or other off the shelf additives. Use only the two mentioned above or a specific strong pH+ control. Those buffers are expecting a full sp gr. They don't adjust the pH. BUFFERS DON'T ADJUST THE pH. Buffers just add chemicals in an attempt to balance magnesium, calcium, and alkalinity in the hopes of strengthening the buffering ability of normal salt water. They don't work in hypo!
Do not add the baking soda or sodium carbonate directly to the hospital/quarantine tank. Always thoroughly dissolve some powder in RO/DI or distilled water then drip/add that in slowly to move the pH up. One of the things about doing this treatment is that there will be some water evaporation. So dripping in a sodium carbonate solution can also help maintain the water level. It's trial and error. Make up the solution the same way each time, using the same amount of sodium carbonate prepared as noted above, and dissolved into the same amount of water. Then practice different drip rates, starting very slowly (1 drop every 5 minutes for a 15 gallon QT) and adjust it faster or slower in small increments until the pH remains the same. NOTE: Sodium carbonate doesn't dissolve well in water. Use distilled water or RO/DI water and add small amounts to it and stir well. Don't add more until what you've added before has dissolved.
If you mess up and the pH has lowered considerably (more than 0.2 pH units) below your target, then raise the pH VERY SLOWLY -- no more than 0.10 pH units per day. A large pH change can seriously harm a fish, especially a sick one.
PROCESS
Lowering Salinity
Over a period of about 36-48 hours (use 48 for most Tangs, Butterflyfishes, Lionfishes, Puffers, and Dwarf Angelfishes) lower the specific through water removal and RO/DI or distilled water additions. Watch pH and temperature of the added water -- match that of the water being replaced. Use only a refractometer to measure the specific gravity. Lower the specific gravity to a reading of 1.008 to 1.009 sp. gr. units. Hold it there throughout the treatment.
Maintenance
If the treatment tank has an active biological filter, don't assume it's working. When salinity is lowered the bacteria sometimes enter into a state of suspension and hold off in their metabolism of ammonia and nitrites. Controlling water quality and especially pH will be the challenge. Check for ammonia, nitrites, and pH twice each day at the start, until readings are zero for ammonia and nitrites. Don't count on the pH to remain steady. It must be checked no less than twice a day and if needed, adjusted.
Make water changes to control organics, ammonia, nitrites, nitrates, etc. If all is steady, still make water changes of 35% or more every other day. After the first water use, the only water to use to make changes is made up water from salt. DO NOT USE DISPLAY TANK WATER to make water changes in a treatment tank, no matter what disease is being treated.
Salinity Control
If the tank water salinity is allowed to go up, the Marine Ich parasite will not be killed or stressed into submission. If the tank water salinity goes below the target salinity, the fish are in danger. HOLD THE SPECIFIC GRAVITY very closely within 1.008 to 1.009 sp. gr. units.
Treatment Time
The fish is kept in hyposalinity 4 weeks after the last spot is seen. After the last spot disappears, the hyposalinity continues for another 4 weeks. If during that 4 weeks, if any spot is seen, the time/clock starts over. There must be a minimum of 4 solid weeks with no spot EVER seen PLUS another four week to verify the fish is cured.
Raising Salinity
Now raise the specific gravity slowly. The raising of the specific gravity is very stressful on fish and this part must be done slowly. It should take 6 to 7 days to return the water to its normal salinity. Raise the specific gravity by about 0.003 sp. gr. units or less, per day. Less is okay. No need to be ultra conservative and go beyond 8 days to do this. BUT in no way try to shorten the time to less than 6 days.
When the treatment time is over, there is no need to add back RODI water to compensate for water evaporated. Let that be part of the raising of the salinity. When you go to raise the salinity, add small quantities of high specific gravity mixed and aged salt water.
Continue to monitor all water parameters and chemistries.
PROOF
Verification
After the salinity is returned to normal, hold the fish in the treatment tank for another 4 weeks to verify it is cured. Look for spots every day, very closely. Observe the fish behavior, breathing rate, flashing (scratching) and look for any other Marine Ich symptoms. At the end of this time, the fish is cured/free of Marine Ich IF no other symptoms are seen/observed.
