I am really quite surprised why anyone would like the SpectraPure LiterMeter. I bought one about a year and a half ago and was shocked by the lack of quality for the price that they charge. For my small tank (29 gal) I needed a device to deliver a steady flow of Kalkwasser overnight. The LiterMeter would shoot like a machine gun for about 15 seconds, then remain silent for about nine minutes. This highly uneven dosing procedure was completely unacceptable since I was dosing directly into the tank (I don't have a sump). I called up SpectraPure technical support to see if my unit was defective and even let them hear how loud it was over the telephone. The assured me that there was nothing wrong and it operated as designed. Needless to say, I sent it back very quickly and fortunately got a full refund.
I looked all around to find something of high quality and came across a product from Reef Dosing Pumps called the Sentry. It is based on a high-precision medical pump, is built like a tank, and lets me connect it to a timer/pH controller so it delivers only when needed. Furthermore, I can control the dosing to such a fine degree that I literally can add one drip per second or even slower. I have had it running continuously (and silently) for a year and a half without ever having to do any maintenance on it.
As a VP of Engineering I honestly can't see how anyone can shell out $300 for a LiterMeter that uses a motor that my son has in his toy racing car. The housing is cheap soft plastic, the peristaltic rollers are cast and uneven, and the electronics also consists of a cheap circuit board with no conformal coating. In contrast, I have recently found out that the Reef Dosing Pumps Sentry is based on a medical unit that costs over $1000 when new. Additionally, since it was designed to be used on human beings, it obviously had to pass the toughest quality and ruggedness standards set by the Federal government. Otherwise, the medical manufacturer would be sued by the public in no-time.
I would NOT use a LiterMeter if I got one for free! All you have to do is open it up to see that is a very low quality product. The Sentry from Reef Dosing Pumps wins hands-down.
NOTE: I am in no way associated with the Sentry product. I am just and Engineer who demands high quality in all the products I buy whether it be a car, toaster, watch, etc. Sorry if I sound so tough about the LiterMeter, but I just can't stand shoddy products, especially when the price far exceeds the value.