I just built mine for my 300gal and I used [email protected] 24" oc to support the tank. Mine is acrylic so I used [email protected] 12" oc for the tank bottom. Then I wrapped 3/4 ply, glued and screwed/nailed it. Most tank stands I have seen in the lfs are similar to yours or not as good for the same or larger tank. It is probably ok, but, for me it seems to scarry. I want to feel comfortable putting my body under it. I would beef it up a little.
That stand is very strong and will be fine. The verticle compression capacity of plywood (especially 3/4") is very high. I build cabinets and am currently building a stand for my friends 150 gallon. My design is different but I am using ONLY 3/4" plywood. The front of your cabinet (between the doors) looks like solid wood with the stiles joined to the rails with pocket hole screws. this is also a very strong construction method.
If your super paranoid of coarse you could beef it up. But I wouldn't bother.
The compression is straight down, if the stand is not pefectly plumb, there are shear forces. Then you are relying on the corner attachment. I would not worry about the weight crushing the ply. straight down, but if you floor is not level, or if it gets bumped in one side or the other . I would block the corners to tie it together better, then add a few more just because I like to sleep at night. :wink:
Hey, if it makes you feel safe, make it better.Put your carpentry to work. :thumb:
Add 4 x 4s in the corners, or 2 x 4s, either way. Always better safe then sorry.Whatever makes you feel better. :wink: