Personal opinion, but dosers are very expensive... I think it would be a better use of money to invest in a calcium reactor. The new Two little fishies triple doser is around $350, and you can get the basic reactor with C02 regulator for about $400 or so. While the initial investment is higher, upkeep is much lower. You don't have to keep buying those expensive supplements like calcium buffers. You would still need to add iodine, but not calcium, carbonates, strontium, and other traces. The substrate in the reactor needs to be changed about every 6 months, but it can also be used for sand in the tank.
Sonny