Pat Brennan wrote:
Zerotol is a broad-spectrum algaecide/fungicide that is labeled for plant
use (as compared to being labeled for use on hard surfaces). It has a zero
hour REI and requires no respirator. It is available from most of the
grower supply companies. The smallest size I have seen it sold in is a two
and a half gallon jug which sells for more than $100. It is my
understanding that its chemistry differs from Hydrogen Peroxide by one
oxygen.

No it doesn't.

Hydrogen dioxide is just a synonym for hydrogen peroxide, H2O2.

Somebody will eventually start selling water as "dihydrogen monoxide,"
and people will rush out and buy it, thinking they've got something
new.

Concentrated H2O2 can be bought for less than Zerotol sells for.

J. Del Col