I have that same hydro unit minus the light. I use a 175 MH for light.
The hydro unit works good if you want to keep your plants on the small side. Its a quality unit reasonably priced.
The nice thing about this unit is it is compact, so you can put one light over it and get good results.
One thing I did was plumb it into a master reservoir so changing the water or adjusting the ph is much easier.
Actually I have two units.......one of the 6 plant and one of the 8 plant.
I would suggest you get a MH either a 175 or 250 or a 400 watt.
Another thing you can use a MH all the way through the cycle. I know everyone says you need a hps and its true you will get bigger heavier buds......but you can get big heavy buds with a MH only too.
The reason I know that is I have done many times.
Also if you change your nutes every week and keep the water topped off.......you dont have to worry about ppm......the reason people here monitor the ppm is because they want maximum growth at all times.
Or they may want to keep an eye on the water quality.....a lot of people have very hard water.
Hydrponics is the best way to grow and its not rocket science when your doing it on a small scale like most of us.
Good luck and keep us posted.