Neodymium magnets/Sharpies in RODI container

[srit1]

Is it safe to leave small neodymium magnets like pictured submerged in my RODI container (Brute 32g opaque gray plastic trash bin)? I use a pair of them to transfer the water level to my outside markings so I know how much water is being used in top offs and water changes. Alternatively I could mark the inside with a sharpie, is that safe, will it wear off?

 

[JPags]

You can buy completely sealed magnets I used them on frag racks I built they are widely used in reefing so you know they are safe