1st time apartment renter, is this white mold?

There is a calibration procedure for those digital temp/humidity gauges. I'd get a reading with another gauge. Almost 90% RH with a/c running means the building has serious problems, the a/c system has problems or the gauge is inaccurate.
 

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I always used AcuRite brand meters back we the kids and I kept hermit crabs which require ~85% humidity all the time, and the cal check on them is done like this:



Pretty rare to find one off more than +/- 3%

Either way, even 70% humidity is too high in a situation like yours.
 
AC runs 24/7
I worked apartment maintenance for 1.5 years. If the A/C runs nonstop then maintenance needs to be in there asap. This will burn out the unit. It's either bad batteries in the thermostat which can cause issues cooling, low refrigerant, a bad compressor etc.
 
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Is this a ground floor unit? Is there a drainage issue outside?

I’d go get a second $12 humidistat at Hone Depot to verify. I would be able to feel 80+% humidity the moment I walked into the apartment. That is a breeding ground for mold growth at that high of RH and not good for your lungs, furniture or the building itself.
 
I always used AcuRite brand meters back we the kids and I kept hermit crabs which require ~85% humidity all the time, and the cal check on them is done like this:



Pretty rare to find one off more than +/- 3%

Either way, even 70% humidity is too high in a situation like yours.

I've currently got the hygrometer in a plastic bag with a salt filled soda cap and a few splashes of water. 3 1/2 hours to go.
 
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I worked apartment maintenance for 1.5 years. If the A/C runs nonstop then maintenance needs to be in there asap. This will burn out the unit. It's either bad batteries in the thermostat which can cause issues cooling, low refrigerant, a bad compressor etc.
I was instructed by management to run the ac 24/7 to keep moisture at a minimum.
 
Is this a ground floor unit? Is there a drainage issue outside?

I’d go get a second $12 humidistat at Hone Depot to verify. I would be able to feel 80+% humidity the moment I walked into the apartment. That is a breeding ground for mold growth at that high of RH and not good for your lungs, furniture or the building itself.

Yes, It's ground floor. I've also got a humidistat that I'm testing for accuracy. 4.5 hours in and is only 5% higher than it should be. 3.5 hours to go.
 
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It's only about 4-5 points off after purchasing it about 9 months ago. So it's still in the 70s and 80s humidity wise in the apartment.
 
Are you paying for electricity? Does it seem higher or lower than it should?
 
I was instructed by management to run the ac 24/7 to keep moisture at a minimum.
That means that the apartment complex you live in A) Has clueless and or inexperienced maintenance Technicians B) The apartments have abysmal insulation and ventilation or an undersized unit as the A/C should NEVER be ran 24/7. It's designed to get the temp down quickly and remove humidity then turn off. Go ahead and replace the batteries in the thermostat. Bad or weak batteries can cause issues.
 
That means that the apartment complex you live in A) Has clueless and or inexperienced maintenance Technicians B) The apartments have abysmal insulation and ventilation or an undersized unit as the A/C should NEVER be ran 24/7. It's designed to get the temp down quickly and remove humidity then turn off. Go ahead and replace the batteries in the thermostat. Bad or weak batteries can cause issues.
Batteries made no difference.
 
Bouncing around between 88 and 90 today with the rain. Here's a photo of how small the apartment is. Used to be hotel rooms in the 70s or 80s. Kitchen is off to the right.
What State and City are you located ? It's not even that humid in my basement .
 
If the AC is running constantly it should be much drier inside than 80%. Long AC runs are good for humidity removal. I think the sheets and your clothes would feel damp at that humidity level. Is water dripping from the ac unit outside? Maybe there’s a groundwater issue under the slab. I’d pester maintenance and have them bring in a dehumidifier and see what it does to the humidity level. What’s your location?
 
If the AC is running constantly it should be much drier inside than 80%. Long AC runs are good for humidity removal. I think the sheets and your clothes would feel damp at that humidity level. Is water dripping from the ac unit outside? Maybe there’s a groundwater issue under the slab. I’d pester maintenance and have them bring in a dehumidifier and see what it does to the humidity level. What’s your location?
This! longer a/c runs are better for removing humidity. Thats why you don't want to oversize an a/c system.

If the a/c is running 24/7 either its not working correctly or there is a water leak under the building/slab. OR BOTH!

If your complex can't correct it, i'd move. That's not healthy at all.
 
What State and City are you located ? It's not even that humid in my basement .
If the AC is running constantly it should be much drier inside than 80%. Long AC runs are good for humidity removal. I think the sheets and your clothes would feel damp at that humidity level. Is water dripping from the ac unit outside? Maybe there’s a groundwater issue under the slab. I’d pester maintenance and have them bring in a dehumidifier and see what it does to the humidity level. What’s your location?
Hampton roads Va.
 
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