A lot of folks have set up tanks using beach sand (imagine that, sand from a beach!

). More than a few have used Ft. L. sand, as you. A lot depends on
where you actually get the sand.
ANY sand can be "cleaned" and used with absolutely zero threat of "permanent bacteria." However, you can get impure sand, or sand with unfavorable organisms/pathogens... for sure!
So, what to do? If you are not sure you can always bleach the sand. That will get any/all live impurities. You can do this by
first filling a 40G garbage can about 1/2 full with WATER. Then, dump in one gallon of bleach.
Then gradually "stir" in the sand. Do this slowly, ensuring plenty of contact time. After this is all done, let it set overnight. Now, you get to do the strenuous job of
rinsing the sand. You don't want any bleach getting in your tank... I'm not sure how long it would be harmful, but it's just not a good idea to try and figure that one out!
To rinse the sand, you should drive down piece of PVC pipe (if you can do this
as you add the sand (dump the sand in around it) you won't have to force it down, and you can even use smaller diameter. Now, you want to seal up a hose to the top of the tube and let the water run continuously to flush out the sand. Again, this type of application can vary according to how much sand, the efficiency of the flush, etc.
You'd want the sand to totally dry out if you're not sure if it's rinsed well enough.
Now, I have to interject with an opinion.

We did a few "beach runs" ourselves. In fact, Dale might remember the infamous "Monty and Smitty Beach Run."

Here's my opinion: You
CAN use beach sand from many parts of the coast... but
WHY????? Have you collected it? Have you cleaned it? It's backbreaking work, it's a pain to haul back up to the truck, it's a pain to do all the rinsing/cleaning, if you
don't have a pickup truck you're pretty much guaranteed to make a mess in your vehicle... and in many areas you can get
FINED for removing
ANYthing from the beach. :shake:
We learned the "hard" way. After the gas, trouble, etc., it was
WAY worth it to just spend a few bucks and get a few bags from the local hardware store.
HTH!