While i wait for more layers for my DIY foam mattress, I've placed my old innerspring *on top of* the foam mattress--because, as is, i can't sleep on the foam mattress yet, and I don't have room to prop it against the wall (where my old innerspring has been spending its time).

Question: Is this hurting the foam mattress? Compressing it too much, too consistently? And when i place the memory foam and latex toppers on the foam mattress, and--if i don't like it still--place the innerspring back on top, temporarily, will this hurt the memory foam/latex? Just wondering if it's bad for it not to have a chance to 'rebound' or breathe during several days.

I know this is an odd set-up, and an odd question, but any replies are appreciated!!! :)

It will depend on the uniform density and construction of the MF and the type and blend of the latex. The highest quality examples of these two foams can be compressed for a year or more and return to form. The lowest qualities have problems after a few days. There's a wide, wide variance.

The MF is Sensus, and the latex is Talalay (supposedly!) from FBM. HR foam under that.