When “HL” error message is flashing, it means the system shut down because the water temps in the spa reached 112ºF (44ºC). In this condition, only Smart Winter Mode will remain active. DO NOT GO IN THE WATER. Remove spa heat cover to allow the water temp to cool down.Click to see full answer. Similarly one may ask, what does HL mean on hot tub? system shut the heater down Beside above, how do I fix the hardness in my hot tub? If your hot tub’s calcium hardness level drops below the recommended 150 ppm the easiest and most common way to raise calcium hardness is by adding a calcium hardness increaser such as calcium chloride to your hot tub. Keeping this in view, how do you fix the OH code on a hot tub? Open the spa cover and let the spa cool down for 10 minutes, then touch the control panel to reset the circuits, or push a red reset button on air systems. For OH, HH or HOT trouble codes, an overheating hot tub is not usually a heater problem.How do I reset my hot tub control panel?You can reset a hot tub control panel by switching it off, waiting for between 10 and 20 seconds and then switching it back on again. If the error signal continues on the control panel then you will need to consult your hot tub manual to see what the problem is.