For swimming, you need a specialist HRM strap - I'm pretty sure the Tickr X doesn't work in water.
Three choices for swimming:
a) a HRM chest strap that has a memory so that you can pull the HR data off it at a later point in time, ANT+ or BT signals go about 1" in water
b) a Polar OH1+ HR sensor that you can attach to the goggle strap so that it gets your HR off your temple. It has a memory so that the HR data can be downloaded at a later date using the Polar App.
c) an up to date watch that does wrist based HR even when swimming. The later Garmins do this, the earlier ones the sensor wasn't good enough to work reliably when swimming.
I've used all 3 and I much prefer the simplicity of just having to use my watch, but that's obviously that's not good if you can't wear one.
For my a Polar OH1+ is the next best as it means I don't need the faff of wearing an HR strap, but I had to write something to combine my swimming data (from my older Garmin that didn't do wrist based HR) with the HR data, and that was a faff to get working.
Women may find a strap easier as you can wear a normal waterproof one under a swimming costume and it won't move about when pushing off from the side of the pool. If you're not wearing anything on top then you need one of the special swim HR straps that are more grippy (and slightly less comfy).
Can you not wear a watch on the other wrist just for doing sport/swimming?