Unless you have a small tank using a dosing pump to do water changes is a bad idea. The pump will burn out as they aren't really made for that purpose.
DOS pump MTBF is 5000 hours * 60 min/hr * 250ml max DOS / minute gives about 75,000,000 ml until the average DOS pump dies. That's about 20,000 gallons. You can do the math from there to estimate how long it will last. It's about 6 years if you're doing 8 gallons a day. If you cut the pump rate to 125 ml/min you just may have just cut your pump lifetime from 6 years to 3 years (depends on how they tested it and what 5000 hrs really means to Neptune).
DOS pump MTBF is 5000 hours * 60 min/hr * 250ml max DOS / minute gives about 75,000,000 ml until the average DOS pump dies. That's about 20,000 gallons. You can do the math from there to estimate how long it will last. It's about 6 years if you're doing 8 gallons a day. If you cut the pump rate to 125 ml/min you just may have just cut your pump lifetime from 6 years to 3 years (depends on how they tested it and what 5000 hrs really means to Neptune).