The problem you are having as Pyro has suggested is that not enough pressure is building up now almost 2weeks later. I personally do not think you have an issue with the diffuser but what I do gather from your explanation is that your brew mix isn't performing optimally if its giving
no co2 output after
only 1½ weeks. You should still be getting enough Co2 output to still maintain good levels depending on your size tank.
Here is my brew mix that was used for 1½yrs in my 20gal tall with a Rhinox 5000. Every 2 weeks a new brew was made so that Co2 levels were always optimal.
2 Liter soda bottle
2 Cups Sugar
1 Tsp Yeast 'not the fancy ones'
3Tsp Baking Soda
RO/DI Water to where bottle Curves
The mix above will give good performance in a 20~29 gal setup with any plants
but the mix
will have to be changed every 2 weeks.
DIY often builds up a yeast 'snot', especially if you don't use a trap. If that's what you've got, it will be a little harder to remove.
If you have this buildup (which will happen in time) you can also boil the diffuser in bleach water for 5~10min. I do not have a set amount of bleach that I use, I just pour in to what I think is enough to get good concentration. After boiling I let it cool to touch, proceed with shaking the diffuser to get the bleach water thats inside the chamber out, boil it again in fresh water with 1 cap of prime until the chamber is filled with water and then finished up with a final shake. It takes a total of 20~30min to get my diffuser
ultra clean.
This procedure I've been using for almost 2yrs now with the same diffuser "R5K" and have never had any issues. I've tried all types cleaning methods but the process outlined is ultra quick, gets the diffuser super clean and gives the best performance! If it's too much for you to do I understand
Good luck!