Did you postprocess and stack your images?
First, remember that the filter wil not make the nebula any brighter, it simply makes the background sky and stars dimmer, while the good narrowband filters will only attenuate the nebula by a little (cheap narrowband filters will attenuate more, and require longer exposures). A narrowband filter basically makes something like a Bortle 7 picture look like Bortle 4 to 5 picturer, depending on how narrow band it is -- the narrower the passbands, the darker the sky. And they only work with emission nebulas.
A single frame with a slow OTA will still show very little brightness, even for something as bright as NGC7000. They just need to be properly histogrammed (stretched) with post processing.
Here is a single ASI2600MC 180 second, gain 100 image of NGC7000 on an FSQ-85 with a 0.73x reducer (330 mm focal length @ f/3.8), and a Radian Quad filter):
If you have an f/5.6 OTA, expect to expose an ASI2600 with gain 100 for 360 seconds to get the above, and with an f/8 OTA, expect to expose for 720 seconds to get the same brightness. With gain 0 (10 dB less gain), and a f/8 OTA, until histogrammed properly, the single frame would show almost nothing with a 300 second exposure.
Next is a stack of just 6 of the above captured images, and postprocessed with AstroPixelProcessor, Affinity Photo, and macOS Preview (equivalent to a 1000 second exposure at f/3.8 and 10 dB of camera gain):
Remember too that nebulas are extended sources; so, fast f-numbers help, no matter whether you are undersampled or oversampled for stars. The above images are basically a little faster than f/4. With a f/5.6 scope, you would need to double the exposure time to get the same image, with an f/8 OTA, you would need 4x more exposure time (total integration time of 4000 seconds, with ASI2600 at gain 100) to get the second image.
Avoid cheap filters; you get what you pay for. I know it is too late for you. Get at least Antlia or Optolong quality class. If you can afford it, get Astrodons and Chromas. You will eventually get disgusted with the cheap filters, and end up in total paying more when you end up upgrading the filter (this is how the poor becomes poorer). Cared for properly, filters last a loooong time; treat them as a long term investment. Thay will outlast many, many cameras as long as the size is suitable for future cameras.
With NGC7000, for example, look at the bright star Cyg Xi -- the bright star near the bottom right of center in the above images. Cheap filters will show bright halos and other aberrations. With the Horsehead Nebula, the Orion belt star Alnitak is a good star to judge quality of a filter.
I did notice that on NGC 7000 when I tried with the Luminance filter
With respect to your comment about Luminance filter -- with a good narrowband filter and the same exposure settings, (1) the brightness of NGC7000 nebula itself with the H-alpha filter should be really close to the brightness with the Luminance fiter, and (2) the background sky with the narrowband filter should be virtually black compared to sky background with the Luminance filter. If both cases are not true, return the narrowband filters, since those are the bare minimum of what basic narrowband filters are supposed to deliver.
By the way, I notice you are also using a ZWO filter wheel. Those wheels have terrible light leaks right around the white stepper motor. Make sure you use black electrical tape and tape off the gaps between the motor and the metal body of the wheel. Be sure not to tape over the shaft and bearing (there is no leak there).
Chen
