Originally Posted By: JKB
Originally Posted By: chesrae

If you look at the Atlas Scientific probe it would be quite easy. The probe gives DO readings over a Serial connection.

The biggest drawback, is the sensor cable is only 30" long.


This actually shouldn't be a huge deal. I have had great success with very long serial connections over cat6 cable.
You can also run the needed 5VDC over Cat6.
And if if there is some failure rate you can request readings far far faster than you need them.

Originally Posted By: JKB

Originally Posted By: chesrae
You would just need a relay and use that to control the aeration system.


A bit more to it than that. You can use a relay if it is rated for motor loads, but life will be shortened.

These will work with up to 1/2 hp motors at 120VAC: 871 Relay Life will be short, to about 1000 cycles (on/off) I wouldn't go that high with them, 1/4 hp, maybe!

Use a power relay similar to this if you want to run motors: Power Relay Yeah, they look ugly!, but will last quite a bit longer.

I will be using the 871's with 4 small compressors set up in redundant fashion.

Motors 1/4 hp and up, that run continuously, or I need certain performance from them, will get one of these: PowerFlex 40


This is the relay I am using for well control and In general much prefer a mechanical one unless for very small loads. This relay is a bit different since it's coil voltage is 120VAC but it is what I needed for the well system. Since you obviously know more about it than I do you care to comment on the appropriateness of the choice?

Originally Posted By: JKB

It would be interesting to see how you have your well/water system set up.

This post is getting a bit long. I will talk about it below.