So after a few flights with the larger Coolant Tank and never seeing the level change, I got back from the SeaRey Fly-In and looked at the level and saw coolant had leaked on the Turtle Deck. I quickly took off the Cowling and found that the coolant had leaked through the fill plug. I figured the hose to the Coolant Tank was blocked. I took off the hose to the Tank and blew into it to see if bubbles would blow into the tank, but I could not blow into the tank. I removed the Tank and found the hose connection had never been drilled through. Now I think that the pressure build up with no Overflow Tank to take the pressure off might have caused the Heater Control Valve to fail. I drilled the connection ant put everything back together and hope this will end my coolant issues.