Plumbing questions

[USMA36]

I just resealed my 210 and I have a couple of questions. First I'd like to leak test it before I move it into my basement. In order to leak test I need to install the bulkheads and some PVC so the water doesn't drain out the drilled bottom holes. Installing the bulkheads requires the tank to be off the floor. I have the tank on 4x4s so the bulkheads are not touching the ground. My question is this...can I safely test the tank with only 4x4s running around the exterior edges of the tank and no support in the middle? I have attached a picture, the ends of the tank are not supported in the picture but would be before I fill.

My next question is I have 4 drilled holes with 1 inch bulkheads. The included plumbing uses 1 inch drains and 3/4 inch returns. In order to use 3/4 inch returns I'd have to install bushings into the bulkeads. Can I just change the returns out to 1" without any issue? I don't mind using bushings but I'm not sure if PVC cement can be used in the bulkheads or not. I'm not sure what the bulkheads are made from. I bought them at the LFS.

 

[T-J]

If you're unsure about the support, just build out a quick frame using your scrap 2x4s. Looks like you already have enough for the long sides. Just put one on each end, and one in the middle. Make sure everything is level before adding water, and you should be good.