Do you dose the display or the sump?

Used to dose into the sump but decided I like it better when I dose right in front of my vortech in the DT.

 

I used to dose into my overflow box, then when I got a drilled tank, I dosed into the overflow in the tank. I thought this assured maximum dilution before introduction to the DT, like 2in10 said above. At that time I didn't use mechanical filtration, but if I did, I probably would have dosed elsewhere. In retrospect, dosing fluids into the overflow was probably not the smartest thing since the next device down the line is the skimmer. Calcium into the impeller isn't so good, calcium getting foamed away into the collection cup also defeats the purpose. (Whether or not that happens, I don't know).

Every scenario is different, but in general, dosing should take place in an area with high flow, to prevent pockets of water rich in dosing fluid flowing past corals and fish. It's dependant upon the method of dosing. When pouring manually from a cup into the system, the location is potentially more dangerous if done from the wrong area. If you're dripping it from a dosing pump--the location has less bearing.


Now that I use a dosing pump that administers 15-20 drops/minute, I have it dripping into the return chamber in my sump, the next stop is the return pump, then to the DT. With a drip, IMO, the dosing fluid will be readily dispersed without the chance of high concentrations making way to corals. As long as regular maintenance routines are employed, including running vinegar/water through the pumps--calcification of the impeller is less likely to be an issue.