I have run a midwest for almost five years now. Some initial steps need to be taken that take a little thought and fineese and once it is running at a rate according to your nitrate production it is almost maintenance free. The trick in the beginning is to start with a real slow rate and let the unit build up the bacteria to eat up the nitrates, about 1 drop per second. Once your output tests at zero nitrates, increase it slow at only one more drop per second and leave it there until it zeros out again. At first when you test the output the nitrates will show off the charts, mainly due to the unit also producing nitrite as it cycles, skewing the test results. Be patient and let the unit do its work (cycle) and all will be fine. Most people have issues because they try to get it up and working too rapidly. They also tend to cycle better with lower tank nitrates opposed to high nitrates, re 20ppm vs 80ppm. What are your tank nitrates now??
I just rinsed my sulphur and changed the crushed coral media last week after running it for about 16 months straight. Just check your drip rate and watch the in and out lines as they can tend to fill will algae and reduce the flow rate. Also not sure about the Korallin unit but Midwest uses john guest quick connects for these lines, and the tubing is different then regular airline tubing, so if they are the same make sure you replace it with the right stuff or you will have a drip leak at the tubing/valve connection.
PM me when you have the unit if you have questions, I will try to help.
