I need some help with figuring out what topper to go with for my mattress.  I have a latex mattress that we bought awhile ago. It is completely encased - as we bought it before I knew about all the custom options etc... out there.

I don't feel like doing mattress surgery to open it up and replace the layers - so looking to add a topper. Here is what we have. 6" of 40 ILD, 2" of 19 ILD and 1" of 24 ILD. It is supposed to be talaly.

With the plush side up it is no longer comfortable for me. I feel like I sink too much and occasionally end up with aches in the morning. It isn't horrible, but isn't as nice a feeling as when we first got it. Not sure if my body has gotten 'used' to it or if it is possible for latex to soften like that.

So we have it flipped with firm side up right now. I like the firmness - but miss the cushion. I get no aches in the morning with the firmness - but still toss and turn probably more than I should.

Am looking at putting a topper on the firm side.

I have narrowed it down to a 3" topper, but am not sure to go wtih 24 or 28 ILD. (Chime in if you think I should go 2" instead of 3")

We bought my daughter a custom bed and she has a 6" 36ILD core with a 3 " 24 ILD on top of it. Her mattress is awesome and we are very happy with it. Got it from Custom Sleep Design, which I would totally recommend. Let me know if you want further info on them.

So I 'stole' her 24ILD layer out of her bed to try it out on ours. It feels awesome -but strangely feels softer on our bed than my daughters setup even though we have a firmer base. I love the feel of the 24 on our bed, but am not sure if it would eventually be too soft (i.e. could it soften or body getting used to it again). Any input would be greatly helpful. I have bugged the custom sleep design folks about it and they gave me their input and are super nice about it - but figured I would cast a wider net as I know there are a ton of 'experts' out here as well. I am about 5'10 and 145. Mainly a side sleeper. I sleep on my back only when I 'fall off' my side. I will fall asleep on my back if the mattress is comfy enough. Thanks in advance for your opinions!!!

I think that you should go with Custom Sleep Design's recommendation.  They probably get it right more than the folks on this forum.  They obviously got your daughter's bed right and you will get so many different opinions here that really don't know your needs.  Maybe I'm a little slow, but it's kind of unclear what your ILD's and dimensions and what layers are that you are trying to fix.  My opinion would be to go to a 24 ILD (of those mentioned) and start out with 2" instead of three and add later if necessary but I'm no expert and I would think you actually need something softer as a side sleeper but what do I know.  I'm a side sleeper too and CSD recommended 2" of 14ILD on the top (top half of the bed) and something firmer down by my hips.  I think there is more to it than height and weight.  CSD's web site asks for body shape for example, so at least they are doing it scientifically rather than guessing.  I think their method for making those decisions is sound.  Sorry I can't be more helpful.  Let us know how it comes out though.

2" topper is often not enough for latex and especially memory foam.

It seems you do not want to sink in too much? Which means you prefer a medium foam hardness.

I would go : 1" of firmer 28 IFD on the bottom and 2" of softer 24 IFD on the top.

If you want a plusher feel change the 2" to 19 IFD.