I'm sorry for your loss.
I would think that turning your filter off at night isn't a good idea either. In the time that your filter is off, it's drying out and all that good nitrifying bacteria is dying (not a cause of your nitrate, but still a good thing to avoid).
I think what Tstone is saying is that you can put the air stone inside your HOB filter that way the water going inside the filter will become aerated.
I wish the best of luck to you!
I would think that turning your filter off at night isn't a good idea either. In the time that your filter is off, it's drying out and all that good nitrifying bacteria is dying (not a cause of your nitrate, but still a good thing to avoid).
I think what Tstone is saying is that you can put the air stone inside your HOB filter that way the water going inside the filter will become aerated.
I wish the best of luck to you!