If your KH test kit is working right you have very alkaline water, but just high calcium/magnesiun concentration, and not too high at that. Did you or do you add baking soda to the tank? That would drive up the KH and not the GH. The drop checker will not give usable results unless you use distilled or deionized water in it, with a known KH due to carbonates only. The Red Sea instructions are just a way to measure the tank pH using a drop checker. And, 30 drops per minute are not going to be enough CO2 for a 55 gallon tank. Something like 3 or 4 times that amount might be enough, depending on how the CO2 is introduced and whether you are losing CO2 at the water surface due to agitation of the surface.

You can buy known KH, distilled water solutions, that will make the drop checker measure the CO2 ppm in the tank water from KH Standard