I have a blue long water filter under my house that needs to be changed i called a plumbing company and they wanted to charge me 5 "WTF" Im pretty thrifty so i want to try and change it myself. Ive tried to change it before but i could not unscrew it out of its base. What i need to know is how do i unscrew it because i think if i can take it out then i can change it, thanks in advance.
(That link seems to be pretty helpful but mine should be easier to install right? Because it just needs changing out.

My plumber recently installed a water filtration system under my kitchen sink and when he left I noticed that the filter was hooked up to the hot water instead of cold. I called him and asked him what to do and he told me to shut the water off. So now I am just wondering if it has been damaged because of the hot water running through it. Thanks in advance!

We are in badly need of such water treatment chemicals, thanks in advance.

I would like to perform a test to see if my Brita Filter cartridge is still effective. What would be your suggestion in designing an experiment to test the water filtered by these cartridge?

I have access to use microscope, petri dishes, incubator, x-ray diffraction machine, gas chromatography, pH meter, and regular chemical experiment equipments.

thanks in advance