Hi Josh,
The piping is ABS. There is some debate as to its use in aquariums (fear of leaching something??) but I think the main reason ABS isn't used for potable water lines is because it doesn't withstand pressurization. The drain isn't under any pressure load though and my reefs been running for a year with it so... I will leave it to the debating society.
My returnline is 1/2" and my drain is 1 1/2" so it can handle the flow. My reef has a slow turnover rate anyways as it was set up for seahorses (they don't like high flow) and is augmented by a closed loop recirc system.
If you go through the link for the tank build you will see that I test everything in my garage first so that I can make adjustments if needs be.
It gurgles a bit but not that much. When the hood is closed it's silent.
I have no idea about the stand/table but there are two forces at play to consider:
The downward pressure
The lateral sheer pressure.
The downward pressure is pretty straight forward but the lateral sheer pressure is tricky. This is the pressure exerted as soon as the weight is shifted off its center of balance ie. if you bump up against the table. Most tank stands have cross bracing to withstand this pressure. I'll edit this post later with some things to look for when evaluating that table.
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