I just refilled it and it runs fine for awhile, but then the "FL" code appears and shuts the system down. I can flip the breaker off for awhile and then reset it and will work fine for awhile again, but will always go back to the "FL" error code. Any help would be greatly appreciated!

Can you post a pic of the equipment or some model numbers?

It's my parents' spa and I'll have to follow-up on a model number once I get over there. Thanks!

The model number is VKI100. Any help would be greatly appreciated!

Sorry, I should have specifically asked for numbers off the control. In any event, you have a flow problem on the pump that puts water through your heater. This may be a small circ pump or a larger pump that runs on low speed to filter and heat the spa.

Given that you just drained and refilled, it's likely that the pump is air locked. The simplest way to solve this is to find the pump that runs the heater and open one of the lines on it to allow the air out. This will also allow a lot of water out, so don't wear a suit and tie or anything fancy.

Other possible issues include but are not limited to:
- A bad pump
- A dirty suction side filter
- An uncalibrated pressure switch, faulty flow switch, or faulty M7 sensor depending on your system

Try the air lock first.

Thank you very much for the "pointers"! I'll take a closer look at it next time I'm over there.