please help

You asked about affecting the amount of gas.

So I will answer that question.

Science 101:

the amount of the gas will be in the ratio of the water's chemical makeup: H₂0 means

2 parts hydrogen for each part of oxygen.

http://genchem.chem.wisc.edu/demonstrations/Gen_Chem_Pages/03stoichpage/stoichiometry.htm

throwing in eye of newt, vinegar, nor salt will not alter that ratio . You will only get the amount of hydrogen and oxygen by mass equal to the mass of water being electrolyzed.

Electrolysis of Water

Pure water does not conduct electricity, because the numbers of H⁺ and OH^- ions are small (10^-7 mol/L each). In the presence of an acid, water can be decomposed.

A potential of -2.06 V is the standard cell potential for, Pt | H₂O, [H⁺] = 1 M | O₂ || H₂O [OH^-] = 1 M | H₂ | Pt And when a potential greater than 2.06 V is applied such that the forward cell has a positive potential, the following reactions take place.

Note that the acid and base must be separated by a salt bridge to prevent the neutralization reaction. This cell potential is different from the cell potential for the reverse reaction in pure water, for which [H⁺] = [OH^-] = 10^-7, and E° is 1.23 V.

Source: http://www.science.uwaterloo.ca/~cchieh/cact/c123/eltlysis.html

The addition of these only affects conductivity, not quantity produced.

That's the science.

MAy I advise you to look up Blink's posts to save yourself a lot of trouble?

http://cr4.globalspec.com/thread/30594#comment318952

Heres a recent one, but he has several past ones that are outstanding tutorials.

Don't forget to wear safety equipment, especially eye protection!

milo