Been playing with this a bit more. In Home Assistant you can install and add on called ESP Home and then use little Arduino boards to make all your sensors wireless which then communicate with HA via ESP Home. Then you have a single dashboard where you control everything from whether its relays, wifi switches etc based on the data from the sensors. I am also using Mqtt in the same way. Lots of very clear documentation so its good for code mongs like me
How do you plan to drain the tables back into the res as a 750L res is not going to allow for gravity draining?