I have a 10 year old hot tub built by a local company here in michigan. I have had very little issue with it up until this summer when the lights quit working and it stopped heating. I popped the top on the heater to find the element covered in calcium or whit crystals. I assume I need an element or a new heater?
The tag on the heater says
Vertical Heater assembly
4.0 Kw/240-EP
Plastic Enclosure

So can I upgrade this unit to a larger heater? it takes a good day to heat from 80 to 105. I would like it to heat faster.

Also the fiber lights don't work so I pulled the lightbox which seems to work ok with 110v applied to it. it is plugged into a small control box EXM-5-AMP. Is there a replacement for this unit? Do they go bad.
Thanks in advance for the help.