From JBJ's manual on their chiller:
Q: How do you Back Flush a chiller?
A: Over time, the titanium heat exchanger will accumulate calcium build up that will impede the cooling process. You may also have particulate matter and debris accumulating on the integrated temperature probe giving inaccurate readings. We recommend Back flushing the chiller every 6 months.
Step 1
Items needed:
a. 5 gallon bucket
b. 3 gallons fresh water
c. 1 gallon of household vinegar
d. Submersible pump
e. Vinyl tubing
Step 2
Add 3 gallons of freshwater and 1 gallon of household vinegar into bucket.
Step 3
Connect vinyl tubing from the buchet to the submersible pump and into the “OUT” side of the chiller.
Connect vinyl tubing to the “IN” side of the chiller and place back into the 5 gallon bucket.
Step 4
Let the pump run through the chiller for 1 hour in the opposite direction. This will help clean the temperature probe as it is located on the “IN” of the chiller.
Step 5
Turn off submersible pump after 1 hour, and discard liquid inside the bucket. Refill the bucket with 4 gallons of fresh water and run the submersible pump for another 30 minutes to remove any residual vinegar from the chiller.
Step 6
Reconnect chiller to original set up and re-program the set point back to your desired setting.