Magnesium Malate.
https://www.isotrope.com/magnesium-malate/

I didn’t like the float experience but I do ad magnesium salts to every bath I take and use a magnesium lotion for some relief

I’ve floated once a week for six weeks and have found relief. The first float I too had trouble relaxing due to not knowing what to expect. Since then, I have been able to relax to the point I fall asleep. I don’t know how it works, whether it is the magnesium or the relaxation without pressure points, but it seems to help. I have been reading up on the science and just wanted to know if anyone else has found it helps.

Also, you can buy magnesium spray mixtures to spray on the body and affected muscles directly.

I tried floating once. I felt great afterwards for a day or two. But its expensive and i had so much trouble relaxing in it as I cant get water in my ears and there is no earplug that keeps your ears watertight when fully submerged for an hour. So I basically spent an hour trying to figure out how to relax while splashing around lol.