Spa/Pool heater = huge gas bill

[Jeff Minc]

I just launched an STR in December with a pool and spa that each have a gas heater. It's my first time owning a pool and spa and now I'm getting hit with huge gas bills. I'm not heating the pool this time of year but allowing guests to turn on the spa heater whenever they want. I can see huge spikes in the gas bill when they use it. How do hosts with spas usually handle this? Do people usually install timers? I'm worried about turning on the pool heater because I'll have to add on a huge surcharge to cover the cost. Any experience or advice anyone has here is much appreciated, thanks.