What humidity level actually stops that basement smell without killing my electric bill?

The sweet spot for most basements is ussually right around 50%, but you have to give the machine enough time to actually pull moisture out of the materials in the room, not just the air. If you just turned it on, the air might hit 55% quickly, but your concrete walls, wooden studs, and storage boxes are still holding onto gallons of water. It usually takes a full week of continuous running before you can really trust the reading on the display.

I'd suggest setting it to 50% and letting it ride for seven days. If the musty smell is still there after a week, knock it down to 45%. Going all the way to 40% is defintely the safest bet for **mold prevention**, but like you said, it'll murder your electric bill because the compressor will almost never cycle off. Most mold species struggle to grow once you're consistently under 50% relative humidity. One thing to watch out for is why the humidity is so high to begin with. If that machine is running 24/7 just to keep it at 55%, you likely have water active-leeching through the foundation or a failing french drain. Dehumidifiers are great for managed dampness, but they can't win a fight against a steady outdoor leak. Check your gutters and downspouts to make sure they're dumping water at least five feet away from the house to stop the source of the dampness.

Also, don't crank the fan to max thinking it'll dry things faster. On many units, a lower fan speed actually allows the air to spend more time in contact with the cold coils, wich can result in more **water extraction** per hour. If the air moves too fast, it doesn't stay below the dew point long enough to condense properly. Stick with 45-50% and give it time to do its job.

That fan speed tip is wild, I always thought higher was better. I'm actually wondering about the sensors on these things. My unit says 50%, but a cheap hygrometer I put on the other side of the basement says 62%. Should I be moving the dehumidifier around every few days, or just getting a separate fan to circulate the air better? I'm realy trying to avoid buying a second unit if I can help it.

Don't bother moving the machine, especially since you have the hose hooked up. The sensor on the unit is always going to be optimistic because it's measuring the air right at the intake. Just get a cheap box fan or a Vornado and put it in that damp corner to push air toward the dehumidifier.

Also, keep an eye on your basement temp. If it's still chilly down there, your coils might be icing up, which kills efficiency. If you see frost, you'll need to turn it off for a bit or up the target to 55% until it warms up. Circulation is usally the missing link when the musty smell sticks around despite a 50% reading.

One thing that relly helped me was getting the unit up off the concrete floor. I put mine on a couple of cinder blocks and it helped with the drainage and air flow. Also, don't forget to check the filter every few weeks. Since you're running it on a hose, it's easy to just 'set it and forget it,' but a clogged filter will make that compressor work twice as hard for half the result. I keep mine at 50% year-round and as long as I keep the coils clean, the musty smell stays away without the electric bill going totally insane.