Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
GH of 9-11 is pretty hard water, highly suited to live bearers, certain rainbow relatives, snails and a few shrimp. It is at the high end of OK for some soft water fish that have been in captivity for many generations.
GH is a measure of calcium and magnesium.
If you want it harder, you can add GH booster or Seachem Equilibrium or any similar product.
If you know your water does not have the right balance between these minerals each is available separately. For example, if you knew you needed magnesium, but were OK for calcium, then Epsom salt is a good source of magnesium. If you knew the calcium was low, but magnesium was OK, then calcium chloride is one possible calcium source.
KH of 7 is pretty good for any of the hard water critters listed above, yet is still soft enough for some of the fish that have been in captivity for several generations, even if their ancestors came from soft water.
KH is a measure of carbonates. To add more carbonates you can add bicarbonate of soda, aka baking soda. If you do not want to add sodium to the water then potassium bicarbonate is also available, I think it is sold for kitchen use, I have seen it for sale on line.
As far as I know the products you are listing have none of these materials, so should not raise GH or KH. Read the labels to be sure, though.
For soft water animals, GH and KH as low as 3 German degrees of hardness is just fine, though I would research the species you are interested in to be sure.
Doing a 50% water change with RO ought to cut the GH and KH almost in half. It is surprising they just about do not change with a 50% water change. That is really odd.
Have you tested the RO water? As the membrane ages it is less effective at removing things.