Thank you Steve for your kind words. As always, you think things through a bit more thorough, so let me try to address your comments...
1) I'm I seeing this correctly? That's two sockets, and two socket pairs (two plugs each) that are being controlled?
It is three socket pairs, making for a total of 6 outlets (A-F in my schematic). The first two (A and B) are switched independently, while C and D as well as E and F are flip-flops. When one of them is on, the other is off. In other words, C/D and E/F are both controlled by a single relay.
2) And that also you have not wired the 5th and 6th controlled circuits to the 120V, but to the 24v because your intention is that they are dedicated to your 24v solenoids?
That is correct... I could have connected the 5th and 6th controller outlet to two more relays, but a) I didn't see the need to switch THAT many things independently, and b) yes, I want to use at least one of them for driving water changes in the future.
3) Are those relays all different? They look like it. Maybe similar function, just what was in your grab bag at the time?
No, they are all identical. In the first picture, I took 4 of them and placed them in different ways so four sides can be seen. Hehe.
I think this would work just fine, or maybe a pair of them. Being limited to two channels at once isn't such a big deal. You wouldn't want to drain and fill your tank on the same time. That should be sequential. So only one channel used there. And if you were doing fert dosing, well you could do that when you were not draining or filling. So again, only one channel used.
The other channel would control your lights, and depending on timing, that too might be on the same control channel. So did I say you might need two of these? Shucks. Sounds to me like one might do just fine!
I think the 6 zones give you quite some flexibility. Keep in mind that in another project I created a Delay Timer to dose micros, and I can connect that one to any other switch. For example, my macros dose at 10:28, while the micros are connected with the moonlight which turns on at 21:59 (lights turn off at 22:00), and they run for like 4 seconds as per delay timer setting.
Two at a time is much better than one at a time... still a bit limiting. For my daytime high light period I have two banks of light running at the same time, so obviously there is nothing else that can be switched during that time. But everything else (moonlights, water changes, fert dosing) takes up relatively short periods so there is a lot of different things that can happen successively after lights are out.