I'm sure a lot of people are already aware of this but I figured I post it again in case someone might have missed it. I had been using the BRS 1.1ml dosers for about three years now. When I first set them up I checked the accuracy of them to set up the programming through the Apex. Both of them were pretty close to 1.1ml. After that I basically just let them run and never thought about it again. Over the winter I got two more pumps to dose other additives and set them up and just let them run. While doing maintenance one day I just happened to noticed two of the pumps running at the same time and saw one of the older pumps going a lot slower then the other newer one. I thought oh man the pumps must be getting old. So I replaced the tubes thinking that must be it. Started them up same thing. So I just figured that's it they are done. Since then I switched to the Neptune DoS and today I was talking to another member who was intrested in the BRS pumps. I got into it about how they started slowing down. Well I had some spare time and said ah let's just see how off they are. I ran all four pumps for 5 minutes and collected the water in graduated cylinders. Can you guess which samples are from which? The two older pumps are still getting darn near close to 1.1ml per minute and both newer pumps were almost double that at 2ml +/- a few tenths. So I just want to say don't be lazy like I was and take for granted that everything is doing what you think it's supposed to. Testing is so important in this hobby and I'm lucky I wasn't dosing something that could have caused major issues being overdosed at 2 times what I thought it was.