Just my opinion, based on what I intend to get and some time spent researching, not real life experience (I have been using HPS/MH/T5 for 10 years....10 years ago and I am checking a bit the led lights considering restarting...anyhow, just my two cents, any comments on what I write are welcome!
Each vivar is 274W (?) and the vivosum is 135 W, so watts are not too bad, but you do not have a good covering and could add a bit more watt IMO (since what you have is a bit old generation of leds)
Option 1: add a TS 2000 mars hydro (300W, 265 US) (or spider farmer SF 2000 or whatever lamp with 300W and full spectrum covering a bit in length)
So you get the two vivar to cover 2.5*5 (and the vivosun for 2.5*2 and the TS2000 for 2.5*3, which is not bad
teh new light are better qwuality than the old ones and you keep 235 US!
Option 2: You get more state-of-the-art (samsung) leds like the SP3000 from mars hydro (or any other brand)
Option 3: Get another vivosun and spare some money, so you have the two vivar and the two vivisum in a square, it should be enough

..or even do a line with 4 vivosun.
Oprion 4: You get a Yuxinou (or whatever chinese brand with samsung lights, UV and IR, 720 W 3 bars (for this if anyone has feedback, I woudl be happy to hear it since it is what I am leaning torward
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