With hobby grade dosers, if you are looking for reliability, a Spectrapure Litermeter is going to be the winner. They will work for 20 years or more. Litermeters are absolutely NOT cheap, mass produced Chinese dosers. They are manufactured in Tempe, Arizona with robust components.
I currently use 2 of them, with 2 remote pump modules as slaves. I bought both of them used, and both of them have manufacturing dates that are 13 and 16 years ago. Ive replaced the tubing on both of them.
Each unit has its own pump and will control 2 additional pumps, each with its own dosing volume. The newer model 4 will control more I believe.
They have to be calibrated, which entails pumping 500ml of water and pressing the stop button when that has been reached, the unit is measuring how many seconds that takes and then it can calculate the time needed to pump any given amount of water.
I use mine as an ATO as well as dosing 2 part. They are rock solid day in and day out. The desired dose is split up into 150 incremental doses over a 24hr period.
Historically they have been fairly expensive, a LiterMeter III is still common in the hobby but a model 4 has been around a while now. Anything from Spectrapure is considered a high end piece. They are not cloud based or WiFi, all of the logic is internal to the unit itself, a plus in my opinion.
I paid $125 for the first used one I bought, and $25 for the “parts only” unit that I bought shortly afterwards. Ends up the “parts only” unit just needed new tubing lol.
The only drawback I’ve found so far is that they have a minimum 50ml per day rate, that is because they spread out the dose 150 times over 24 hours. Early on when I was using them to dose 2 part I had to make the 2 part half strength and double the dosage so the LiterMeter could accurately dose it, I needed less than 50ml per day. Ends up it was an easy workaround.
You really can’t go wrong with a LiterMeter. I will never get rid of mine they have so many uses. There is no reason they won’t work for another 20 years.
I hope someone can use my review.