ATO secondary shut-off

[Werbo]

My ATO reservoir is quite large at approximately 25G.

Do I have to do anything to minimize slime, algae, ect in such a large reservoir.

Is airating the water necessary? Once heard this but his reasoning did not make sense to me.

I should also note that the majority of the time the reservoir will only have 10G. 10G is about 5 days water. I'll only be filling before vacations.