Adding H2O to Pb-acid flooded batteries

I saw something on the VISFORVOLTAGE BLOG. It said please add water after battery is charged. WHY? I always have learned and maybe wrong to add water to dischaged battery then charge it. Reason is water is hydrogen and oxygen. It combines with SO4 radical and makes H2SO4 again and therfore will give you the 1280 for proper acid water ratio. The specific gravity for pure oil of vitrous is nearly 1.89. thick and greasy so it needs to be thinned. Plus after chemical combinations the Sulphate part of the acid solution goes into lead and oxygen from the red lead mixes with the rest of H2SO4 and makes water. So help me and others out - DO you add water first or last?
I am not a chaemist but do electro-plating so I have to know double decompostion.