How to control the water pump in a rainwater tank via IoT?

reverence,

I would like to control the water level in the rainwater tank.
The plan is quite simple: water from the gutters drains into the rainwater tank. If the water level reaches a certain level, the water pump is switched on, which pumps the water out into the rainwater system. Once the water has been pumped out, the pump is switched off.

It would be nice to be able to view the current water level remotely via smartphone/tablet/viewer.

I was initially thinking of such a Chinese sensor + controller:
https://pl.aliexpress.com/item/32968151200.ht...1000016.1.2f5d695dVEvDXF&isOrigTitle=true

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however, this controller will not directly switch the pump on/off by itself. This needs to be done differently, the question is how? Perhaps a good option would be to use the RS485 output and integrate with some smart-home system.
Has anyone already dealt with such a topic and is able to suggest how best to approach the subject?
or perhaps there are some off-the-shelf products on the market ?

thanks

The controller has four relay outputs, two are used to control the pump (preferably via a contactor), two are used to signal a fault (dry-running, overflow).

Or maybe something like this
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type liquid level sensor on Google and you will find a contactor for this if your pump is on 400V.