That is what I am concerned with when I get back and turn it on there is no odor from the bubble plume. Other than an O2 meter is there a way to check lower water. Does anyone know of a reasonable priced meter?
What a great discussion thread. Lots of good questions and ideas.
I think one thing to keep in mind is that when talking about aeration start up there are two specific topics of concern. One is the O2 levels but the other and more concerning aspect of diffuser start up, for the very first time (or after an extended period of inactivity), is bringing up toxic chemical saturated water too fast for it to off gas and get rid of its toxic properties so the toxic water does not kill fish. If we have stale, toxic water below the thermocline and bring it up so quickly it mixes and ruins our good top water we can kill fish because of the toxic water. It is in addition low in O2 but the reason we kill the fish may be because of the toxicity of the water rather than simply being low in oxygen content.
So that raises the question, how quickly does the water gain enough toxic gasses that it becomes a danger? For example, we might be able to assume that an old pond that has never had aeration would have toxic water below the thermocline and it would be dangerous to the fish to put in a diffuser and mix this lower water rapidly. But lets say a pond has regular aeration but the electricity goes off for 24 hours. Would it be dangerous to restart the aeration and run it continuously or would you need to do a slow start up again? My guess is it would not be a problem with only a 24 hour lapse (but of course it likely would depend on the pond). But what about 48 hours? Or a week? In other words what I am getting at, how long does it take for the detritus on the bottom of the pond to infuse toxicity into the low water resting below the thermocline to make it toxic enough for fish that when it is mixed with the upper good water it is still toxic enough to kill fish?
Of course that last questions answer is "it depends, depends, depends, depends". On a gazillion things. But it would still be nice to have some general rule of thumb. For example aeration pump quits and we get another within 24 hours = ok but if it goes a week need to do a slow startup. That is not a recommendation but just an example.
Wow that was a lot to type. Hope someone got something out of that ramble.
