Your problem is why it is an issue that so very few mattresses allow the user to adjust firmness. The user has to try and home engineer a firmness increase or decrease with a "forklift" change via trial of different types and thicknesses of mattress toppers. We see the problem with this "fix" is the expense up front to buy the topper without the buyer having any assurance that it will be the right "fix" for their sleep comfort needs.
So you try one topper and if it doesn't give you the comfort you need then you have to try something else. It's a shame that only inflatable mattresses and waterbed mattresses come with firmness adjustability built in.
We know someone who bought a four inch Serta memory foam topper and loved it. We bought a three inch Cloud9 semi-firm memory foam topper and combined with our waterbed mattress it is perfect for both of us BUT we had to adjust the firmness of the mattress three or four times before we achieved the "perfect sleeper" mattress combo that matched our personal comfort needs.
If the mattress is uncomfortable it is possible that it is too soft instead of too firm. One thing we learned in our personal mattress quest is back and shoulder pain from sleeping on a mattress can have a deceptive cause. In our case at first we thought or mattress was too firm and we decreased the firmness only to learn that the opposite was true and after adding firmness we achieved the sleep comfort we sought.
Anywho, we found the Cloud9 semi-firm three inch topper (on sale at Amazon.com including shipping and NO tax) was the perfect accessory to our latest waterbed mattress (ultra-waveless and extra firmness) BUT only after we got the mattress firmness figured out.
Hope you find the perfect topper that will correct for the firmness mis-match you have with your mattress.
