Hi cathye,
It’s always best to check with a manufacturer about a foundation you are using to make sure it satisfies their warranty requirements but it would probably be fine for a latex hybrid such as the Alexis (which has polyfoam on the bottom of the mattress). If the mattress was all latex (including latex as the bottom layer) then the slats should be a maximum of 3" apart and preferably less. I would also try to secure them so they don’t shift and either fall through or create larger gaps and if your bedframe is one of the larger sizes then it should also have a good midbeam with support legs to the floor to make sure that the frame stays level and doesn’t sag in the middle over time.
Some of the better foundation choices I’m aware of are listed in the foundation thread here (which you may have already read if you know about the powerstack at My Green Mattress which is listed there).
Phoenix