[Fish]

Hey Justin,

For sump dosing, normal topoff pumps will work. The reason I first came across this pump is I was looking for something that would be ultra accurate at dosing even very low quantities (like in a nano) and something that would be able to inject into my pressurized, hidden plumbing, without risk of back-flow.
The pump is a diaphragm style chemical metering pump. This one is an 'A Series' made by Advantage Controls but some other big names are LMI Milton Roy, Pulsatron, and Prominent. They are not made for fishkeeping but are designed for lab work and industrial applications. The pump fires a piston which draws water in then pushes it down the line. The length of the stroke can be changed to adjust how much liquid is added each time and the frequency can be adjusted for how many times per minute (or hour on some models) the pump fires. With this model I am able to dose any amount from 0 - 0.63gph, and it is rated for up to 150psi! That means if I wanted to, I could put this pump in another room in my house or even in my neighbors' house and it wouldn't have a problem getting topoff water to my tank (I wonder if they would let me.... ).
I really don't need this pump for my setup. The only reason I got it is I have used one in the past and am a sucker for a quality piece of equipment. They are super expensive and sell new for like $800-$1000US!!! You can get some awesome deals on them on ebay though.
The first one I had cost $180 off ebay (an engineering firm was clearing some out) and this one I got for only $120US. It never came with any box but the seller claimed it was brand new. Looks like it's in good shape too.
The person who has my original is a member of the board here and was talking about selling it for the same price I paid - $180. They have never used it, but even if they did it would be like it was brand new - they are made to dose things like chlorine and acid... so... ro/di water is easy peasy.

- Chad