I've used a lot of pool filter sand both in my pool's filter, and in my freshwater tanks. It's very, very clean, and needs little if any rinsing. It's not like play sand.
My concern would be that pool filter sands offer nothing in terms of pH buffering, though I'd also say that sand buffering pH is not as important as often stated, in my opinion. I would also recommend an inexpensive aragonite sand or crushed coral substrate, if the OP did not want to go bare bottom.
Here's the CaribbSea aragonite sand on sale for $7 for 10 pounds. Yes, I get the OP has a large tank, and this sand does come in 40 pound bags too, but the 40 pound bags are about $40 each, so the "best deal" would be the smaller 10 pound bags right now:
https://www.petco.com/shop/en/petco...tOqxvrWmIVLh0qN7XRWCixCp4ve3GDe8aAhHXEALw_wcB