Leveling method and Leak protection

[Thresher's Reef]

I am almost ready to build my 25 gallon lagoon w/ APS stand from Innovative Marine. However, there is still one thing that is bothering me... I really only have the choice of putting the tank on carpet due to my apartment being very old and the only non-carpet flooring is in the bathrooms. That being said, I have noticed that the stand by itself on the carpet flooring is just barely not sitting level. I bought some composite shims from Home Depot to hopefully tackle this, but I have read that it is difficult to level a stand with shims on carpet. Is there another way I need to go about it? I saw some people say get a sheet of plywood to place underneath. I also ordered a mat I was going to place under the stand so that, in the case of a leak, maybe it would buy me enough time to catch it before it reaches the carpet. It is a heavy duty mat that is usually meant for catching oil in garage workspaces so hopefully it does the job.

 

[shakacuz]

the mat should suffice. once you put water in the tank you can level it as you fill it up.

 

[Gumbies R Us]

I agree with the mat should be able to keep it leveled