How ofter should i change the air filter for the house?

I am sorry dont know what they are called. just removed and it had thick layers of gunky dust. OMG tottaly gross. i hope we dont get sick. no wonder my husband and daughter are sneezing all the time.

HOW OFTEN TO CHANGE? WHERE TO GET IT? WHICH ARE BEST?
How ofter should i change the air filter for the house?
They are just known as air filters. They keep your coil from getting dirty and it helps stimulated the air flow. Plus it aides in keeping dust down a little bit. Absolutely change it every 30 days. If you do, then you will notice your heat/air unit working more efficiently therefore, keeping your costs down a little more than if you didn't change your filter as you should.

If you have a common size-you can buy them very inexpensively at Walmart-If you have an odd size, try calling a heating and air conditioning company in your area. They usually have all sizes, but they are a little more expensive (even with the regular sizes) as they can't buy them as cheap as the mass market stores.They have all kinds but really as long as you change it like you should, the brand doesn't matter.

Be sure to measure so you have the correct size.

By the way, they also have the washable type of filter. You don't have to buy new ones with it-but to me it's just easier to buy the ones you can just toss out.
How ofter should i change the air filter for the house?
Once a month, but if I live there every day.
Every 3 months
you should normally change the air filter about once every month. if you live in an area where there is a lot of construction such as new housing developments or businesses like i do, you should change it every 3 weeks. you can go to home depot to get the filters. believe it or not, the cheap ones actually work the best.
spring and fall ....
once a month