How long to do research?

How long does it take to reseaerch environment and food ect

It depends on the game speed setting. At normal speed, each level of research takes about 8 hours.

Does the research only affect tanks 1 and 2 and not the sale tanks?

All levels of research apply to all tanks, as do the Magic Plants that you can purchase in the Supply Shop.

Thanks! That's good to know as I only have the iphone lite version and am limited to just the one tank and the selling tank.