Definitely not worried about code for this one. The pump/filter also happens to be 20+ feet away from the closest edge of the pool.
It’s still a good idea to consider the safety issues, though.
The pump itself is recirculating the chemicalized water, it’s a secondary source. That’s what the filtration process is for, right? It’s not tap water. You can’t test water pressure without some part of the equipment being immersed. I’m just saying make sure it’s rated for swimming pools specifically, not just “water.”
One of the unusual things about pools is the method of chemical application. Basically you pour in a bunch of chlorine or a bunch of acid or a bunch of base and wait for it to circulate. Which means pockets of hyper whatever until it has circulated. and wildly varying values until it does.
All of that has to be taken into account in equipment design.
Since you already have a Vera controller, I was wondering whether or not you have explored adding RF sensors to the Vera via the MySensors Project at http://www.mysensors.org ? The project already supports the Vera controller and uses an inexpensive Arduino as the Gateway as well as the remote sensors. While this doesn’t answer the question of which pressure sensor to attach to the Arduino, it does open up the possibility to continue to use Vera for a while longer if desired. The Arduino sensor node could later be modified to use the SmartThings ThingShield for future integration into SmartThings.