Yields vary with different techniques, nutes, strains...I usually can squeeze about 1 1/2 oz dry or so, from a 3 gallon pot. (estimate from decades of purchasing experience. Haven't had a scale in years, tho)

Looks good, just a couple things...

Safety first. Would move the power strip and timers. Water splashes are inevitable.
Careful not to blow-out the pilot on the water heater.
Will heat from the water heater be a problem in the summer? Perhaps a board of some sort between growspace and the heater itself? Could cure both situations. (heat and explosions)

I think that's it. Oh yeah...is the light adjustable, or fixed?

Have fun. :thumbsup: