I have a 125 with a 55g sump and a 110 tall n this corner. The red lines represent the floor joist direction. I was thinking maybe put a 4x4 under the center of the 125, the corner of the 125 and 110 and then the end of the 110. This room is an elevated addition.
Well the tank hasn’t gone through the floor yet so your probably ok, but you are adding another 500 pounds to the equation with that 75 stand so who knows. Personally I would do it.
Yeah, definitely reinforce it, it'll cost you a bit of money, but it'll save you a hell of a mess and the loss of all your hard work and dedication on top of the tank setup. I'd also like to add in that you have a nice tank.
What is underneath the floor? I would put a couple beams perpendicular to the joists held up by 4×4. That would actually help spread the weight. Ideally you would do that before any tank is in n that floor are.
I did something similar and feel better about doing it. Good luck.