[Kazington]

Hi everyone,

I am trying to figure out how to make a calculation to have a rough number of how much chemicals I need to add to reach certain alkalinity or acidity and then neutralise it ~pH 7.

Need to disinfectant my fish tanks and I was thinking to use caustic pearls 99% (pH 14) then I would add hydrochloric acid to neutralise it. After I was thinking of refill the system (pH of intake water is ~6.8) and add Aquades ( HYDROGEN PEROXIDE AND PEROXYACETIC ACID MIXTURE, STABILIZED) to bring it down to pH ~3. And then I would neutralise it with caustic pearls.

In my previous experience I was very dependent on pH probes or ORP probes to understand when I reached the right level but I want to understand how to calculate the rough number.

[Borek]

It can be highly tricky and in general impossible to solve, as it depends on the substances already present  in water. Plus, there is no one answer, unless you add some additional restrictions.