I wouldnt recommend getting beach wood to put in a fresh water tank. If you're getting found wood, you want to go look in fresh water lakes and river areas. Make sure it is clean of course by doing dips and such and letting it sit in tap water for a bit.
Apparently there's a few wood varietals not good for like pine, Elm, softer woods that decompose faster.
If you find wood suitable that is not submerged, it might take a long while to get it to aquarium ready. It needs to dry the sap first which takes forever and release some of the tannins out so it's not leeching super heavy.