Ever used something like this?

[Boatboy24]

My oldest barrel has been in non-stop service for almost 3 years now. I ran across this and thought 'hmmm...'.

https://morewinemaking.com/products/oak-restorer-cw-cool-water-1.html

 

[ibglowin]

Looks good, sorta like Oxyclean or PBW only no peroxide based carbonates and it has a "proprietary plant derived biodegradable surfactant i.e. "soap" which is more than likely something akin to sodiun lauryl sulfate which can be made from coconut oil.

I should probably clean mine with something like this as well but usually I am in a hurry and this says 4-6 hour soak and I don't have enough empty carboys laying around to empty all four barrels at once so it would take all weekend to rotate one out at a time, clean it, rinse it, refill it……..