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- Jul 2, 2017
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That’s interesting. My understanding is that the bacteria need an anoxic environment to grow and consume the nitrate, which requires a slow flow through the reactor. Otherwise, too much oxigen rich water prevents the anaerobic bacteria from doing their thing.This is sooooo accurate! I read another thread that said it was imperative to tune the reactor. I spent $125 on a probe and stand alone meter because Apex won't read negative. I probably wasted 6 weeks fiddling with the flow trying to keep it around -170. This led to clogs, nitrite production, and large amounts of frustration. Finally I just said "screw it" and turned the flow up. Within a month my nitrates were rapidly dropping. Now, my tank is like 5ppm and effluent is 0-1ppm. My ORP readings are +220. Either my ORP probe is wrong (I don't think so because I can make drop almost instantly slowing the flow) or it isn't that important.
The apex can’t read negative ORP, but it is possible to “trick” the apex and select the ORP probe as pH when setting up the probe. This allows you to read the negative values, displayed as a pH range. For example, I know that -170 my reads as a pH of 10 and I just target that value. There are some much better explanations here on R2R in other threads.