If u need doser only with out any other controls I would get the GHL STAND ALONE doser. I have the full set and have it now for two years without any issues
I use one from reefdosingpumps.com. It's dual lines on one pump and it's a medical grade pump that has been refurbished. The part I like is I don't need a timer. It can dose such small volumes that mine runs 24/7 and has for a year now. And because I dose soda ash for alk, the 24/7 dosing keeps my pH at 8.25 all day every day (even at night).
I just got in the 2 part doser from BRS. Supposedly it's made by a company that only makes dosing equipment so it's very reliable. I am hooking mine up this weekend. I got it to dose alkalinity and calcium.
I have 2 dosing pumps but no controller for timers. I have 2 dial timers I can use with an extra power strip. The only thing is it seems to turn on/ off only every 30 mins. Didn't start dosing but would like to start tonight. Is this 30 minute intervals too long?
I use a Bubble Magus for CA, ALK, and MG. It's been running about 6 months fine so far. PH was always good but it locked down like on rails once It all became automated. The only acro bleaching incident since the addition is when some evil critter makes them touch (at least now I know who wins the monti-birdsnest matchup).
I was contemplating purchasing another magus but instead just going to buy just plain $15 peristaltic heads (from amazon) and run them from the apex to do vitamin C and Acro power (based on R2R articles I might add). Those are less mission critical. I'm also thinking of making rotifer soup and just pumping that into the tank but I have to think more about how to get the rotifer and not the sludge and backwash the tubes when done, maybe a timer circuit triggered by the apex.
On one of my tanks I run a GHL, which cost a lot of money, although it is very easy to use and seems to be reliable, as I haven't had a problem with it for about 3 years. On another tank I am running a cheap chinese doser, this unit has run seemingly without incident for the last 4 months, the only downside to this unit is that it is a pain in the *** to program. It requires you to program each individual dosing times, which I find rather inconvenient considering that the interface to program the times is tedious.