I'm new to this so that is alphabet soup. If you could break that down and how to adjust them that would be great.
KH - Carbonate hardness: measures bicarbonate and carbonate ions. Generally raised by adding baking soda sodium bicarbonate.
GH - General hardness is a measure of the concentration of divalent metal ions such as calcium and magnesium (Ca2+, Mg2+) per volume of water. Generally raised by aquarist's by add Seachem Equilibrium, or Epsom salt (contains Mg2+)
TDS - is a measure of the combined content of all inorganic and organic substances contained in a liquid in: molecular, ionized or micro-granular suspended form. Basically all the crap that is dissolved in your water.
RO water - Reverse Osmosis water. Water that has been passed through a membrane that keeps all the crap we talked about above out leaving it with almost 0 TDS.
Ok all that being said, except for very special cases the only way you need to worry about lowering your pH in your tank is by adding more CO2. I would agree with GeToChKn that if you aren't seeing any drop in pH with your DIY its probably not working really well and you have a lot of light. This will likely lead to algae, often lots of it.
Also with that much light you will probably need to be dosing nitrates, phosphates and potassium or "Macros." If you have a really high fish load the actual macro requirements vary. The more light you have the more macros you will need.
I recommend you get some test kits for nitrate, phosphate, KH, GH and get an idea where you are at.