Hello Fishpimpin73,
I believe you have a point there and absolutely right.

Most probably in our hatchery setting, clinical tanks are often used so I do not pay much attention to planted and inverts.

Have used chelated coper sulphate (locally known as 'Copper safe') on set-up tanks on a few occasions but did not see adverse effect. Maybe not enough study on my part to affirm viability.

UV is unable to kill protozoans including velvet. To this,we have tried for a few years...but you are right if used against bacteria.

Regards,
Andrew