# Does HCl kill algae?

I live in the tropics, and have a water tank that sits in the sun, forming algae. Every year, I need to scrub the thing out. The plumber I’ve hired for the job wants to flush my water pipes with HCl to kill any residual algae. The pipes are mostly PVC, with braided metal hose and metal fittings here and there. Should I let him? If not, why not?

• From wiki: Quaternary ammonium compounds ("quats"), such as benzalkonium chloride ... that looks like exactly what I need, thanks :) – neokio Jan 29 '14 at 10:38