I soaked it in a couple tubs with a powerhead and a 1-10 mix of bleach &water for 24 hours then scrubbed it and rinsed it off,let it dry in the sun till dry and didn't smell like bleach.
Then I rinsed the tubs out filled them with rock and water then poured the muratic in at a ratio of 1-10 waited about 15-20 mins till it stopped boiling then added half more waited another 15 mins and poured baking soda in it to neutralize the acid ,ran the hose in each bin for awhile then left them in the sun for a week or so
wear eye protection and some gloves that are acid resistant,it really boils and might get on you.don't get the bleach and acid together or you have mustard gas.
make sure you mix acid to water,the other way around will be very bad for you