It can sometimes happen that due to how the Smart Garden 3 float is assembled, its edges might not align properly.
This can cause a small gap to appear that will allow water to enter the float, making it not float with the water level any longer.
To remove the water then you can try to either drain the float, or a faster and simpler solution is to open the float up (which may require some force), drain it and then re-assemble it, while making sure the edges align back together.
You can find a guide on that here: