hi mfk im getting ready to start my first plywood tank. i want to do a 300 gallon 6x3 tank with a glass window, im still planning and getting my supplies ready. im still looking for a good brand of liquid rubber and ive already looked at pond armor and rubberize it. they both seem to be pretty exspencive and i heard they were suppose to be about $50 a gallon but they are much more. can anyone recommend another good cheaper brand? thanks