For those not using a dosing pump, but otherwise automated dosing thingamajig...

[littlesilvermax]

Originally Posted by Delphinus

I know with the Masterflex peristaltic pumps (lab grade, very expensive, although the occasional good deal comes up on ebay .. also LittleSilverMax had at one point, one for sale, if anyone wanted one of these they should send him a PM) can have interchangeable heads to allow for different flowrates which basically involve different sized tubes or different diameters of the rollers). But the speed at which the rollers turn would be the same for each head so it's still not AS independently adjustable from each other that two seperate feed pumps would be.

I still have that pump. I think it is about $800 new. I paid $300 for it, and I will let it go for $150. I kinda forgot about it. It is infinitely variable.

At any rate, you can have more then one head on it.

It doesn't matter if your rates of calcium and alk are different (consumption) because you can just dilute one of the mixtures more.

FWIW, I was (and am still not) a big fan of pumps on timers. I have gone through a good 15-20 timers in my reefing career and they all fail at one time or another. If they fail on, that can be very bad!