Sue, when I read your post my first thought was 'uh-oh' because I've used my aquarium as kind of a tweaking ground for my reactors; constantly trying to get maximum efficiency. But, I don't think I've ever run the tank higher than dkh12 or Ca 460 or so. Then I thought, well, maybe because the corals have not been growing lately, the alk might have spiked due to lower Ca demand. So I checked this morning, and my alk, Ca, and ph levels are right on the money.

The more I think about it, there are 2 or 3 key events that probably contributed to this. 1) I simply did not stock my sand bed aggressively enough, and an order from inland arrived in rough shape, which I never replaced. 2) the flatworm treatments undoubtedly attacked some sand bed life 3) adding a large fish around this time (copperband for aiptasia control) probably pushed extra phosphate into the system.

I'm going to heavily restock my sand bed, if anyone in San Antonio has some bristleworms, I'll buy them. I'd like to add 100 or more small worms in the next few weeks. I'm also probably going to remove a fish or two and some liverock. Then I'll try building up the tank eco-system very slowly over the next several months.

Oh yeah, Sue, it's likely that your reactor went nuts because you lost fine control over the CO2 input. A terrific solution to this is to use the Dwyer flowmeter to control CO2 flow intead of the needle valve that comes standard on aquarium regulators. It's much more reliable. Also, the first few weeks of running a reactor are a bit sensitive; you're adding a lot of CO2 into the tank, which is good for growth IF it's controlled correctly. And something many people forget is that the reactor is recycling tank water, which means that if you raise your Ca and alk over a few days, for example, then the reactor is now adding Ca and carbonate to water that already has higher levels, and already has a lower ph. Thus, it's effect can snowball. It's sort of a balance issue.