Yes, I would agree with SCSInet. If you can get your hands on a IV drip, then those make awesome drippers.
I use one on my calcium reactor. The problem with gravity fed and pinch type drippers is as the volume decreases in the container, so does the drip rate. With less pressure pushing down on the pinch valve. This is probably not a significant amount, and can be avoided by using a syphon feed out of the bucket as opposed to a bulkhead etc. I used for well over a year a float valve. Now this is what the Kent GF ATO uses. And may be what you've been reading about. However, myself, I have never had an issue with them./ I believe they get a bad rap. You do need to perform maintenance on the valve. Monthly soaking in vinegar works, as well protect it from critters/ But placing it in thee return compartment as it needs to be anyways, and some egg crate or gutter guard as a fence does the job.
Another method I used was a 10 gal with a Aqualifter and float valve. You can place the Aqualifter on a timer and dose only at night this way. However timing it many times throughout the night for short intervals works best. Otherwise the pump will add all the days evaporation rather quickly. Then not much else throughout the night. I have an aqualifter I have used in this fashion(first dosing Kalk, now doing just ATO RO) since February I believe with no issues. These are inexpensive pumps and do work rather well. I am using one feeding my reactor right now.
