I had an aquariumplants.com (now carbondoser) and the solenoid or whatever froze up this year. I called them up and they said it wasnt worth fixing, which is kind of irritating because right on their page it says the exact opposite. (If it ever breaks send it in and we will fix it for under 50$. This is the last regulator you will ever buy!) BS
Don't get me wrong, I had it for almost 6 years without issue, but my point is they can ALL break.
I currently have a milwaukee on a Koralin 1502. Fillling it up is a pain, but once its dialed in the reactor is rock solid. I only use the regular size ARM media. The more coarse the media, the more C02 it takes to dissolve. Some media also is relatively high in phosphates as well.
Make sure you have a GOOD pinch/ball valve too. Trying to adjust a drip rate with a cheap one is an exercise in futility.