Cola soda in holding tanks?

I would think you'd be better off with a few jugs of white vinegar.

I bet any bugs, especially ants would love this method..

While I use Coke for some cleaning items (battery posts, get of diesel smell, etc) I don't think couple liters are enough if you're talking about sensors in your tanks. And I don't know where "light" sensors are in a tank? Going to be hard to get couple liters of coke on upper sensors to do any cleaning.

Look up PH levels and you'll see why coke is good for cleaning some metals.

I think they only gave you half the recipe. A really deep cleaning requires that you add not only a lot of Diet Coke but also a pack of Mentos:

Coke and Mentos

Probably the phosphoric acid in cola helps clean the tank.

I've read about using Coca Cola in laundry to help the detergent. But, I have never tried it.

Consider the Geo Method for your holding tanks.

It could have some credibility?

Click here.

But, I'll just stick with water and a bit of laundry soap or Dawn Dish Washing soap.