Someone please help! I have a 20 gallon long that i have converted up right. This is my second tank now that has cracked. The first one cracked because the heat lamp was hanging suspended above the tank and it fell and cracked the tank, so i went out bought another 20 long. I have been spending the last 2 months or so converting the back with the grteat stuff and i just set it up last night. I put my White tree frog in late last night. Now this was only the uvb light not heat. It cracked again. What am doing wrong.