Growonix would be the brand I would suggest ( all USA made, even their filters and their tech support is good too) , kdf filter with well water, uv bulb To kill all bad pathogens ( why let any chances of root to fuck us over ) and make water last longer
I would suggest even if your a small grower to invest in min 600 gpd r/o so you don’t need a booster and the end result will show that not only is the machine can fill up your 50 gal no problem but replacements are way bigger per gal. This saves you a little cash. Faster filling, bigger filters (cheaper value)
What I do is the “ tall boys” versions of things so they 2x of the filter replacement per gallon( I bought a ex1000 + UV)