My friend, I used to have this issue and with the help of some members here, it's been addressed. First, when they say use tin foil, they aren't joking. It helps a lot. Secondly, try to pick up ceramic heater bulbs rather than heat lamps. The light zaps the humidity. That right there should fix the issue with the foil. However, you might want to look at new substrate. I use a mix of eco-earth and aspine and it holds the humidity in great, sometimes too much.