@nzbaxterman You are welcome - It's a bit difficult to imagine the setup you want, but here a bit more to try and help. All sensors in the barn will need to communicate with 'something' in the barn. Due to all metal walls you may get reflections that will affect signals so moving antennas 20mm at a time to try and find the 'sweet spot' will probably help. Outdoors a 200m run will need a 500mW Nrf24l01+ or you could use lora radios. With the nrf it would be cheap and good to use a yagi (directional) antenna just for this link. You will want a yagi mounted at the barn and at the water tank pointing directly at each other. A helping hand an some walkie talkies would make this reasonably easy! Mount antennas a high up as you can and avoid any obstacles in the path between antennas (including trees). Let us know how it turns out!