Adding Insulation - possible? Recommended?

[aeajr]

I have a Marquis Spirit Hot Tub that is 1 year old.  It is outside on a concrete pad but it is inside a non-heated greenhouse.  We live on Long Island, NY, USA.  Winters can have a lot of days below freezing.
http://www.marquisspas.com/hot_tub/models/the-spirit.asp

What are you thoughts on adding insulation?   Do I need it?  Should I do it?   Would I hurt it?

What type?  How would I do this?

The tub is used year round.   While the greenhouse makes it more pleasant to use in the winter in New York, I was wondering if adding insulation to the tub would be beneficial to reduce electric costs.    I don't even know if there is room to add insulation or if this tub is considered very well insulated.

Idea just came to mind as I was reading someone else's post.

Your thoughts, advice or experience would be appreciated.

[Topline Mike]

According to Jacuzzi, if you add the smartseal insulation package, you will go from paying an estimated $17.75 per month to $11.16 per month.  The "smartseal" is just a half inch foil backed insulation that is glued or stapled to the outside skirt of the hot tub.  So to answer your question, it can be done and it will save you money.  I bought some 2" thick "seconds" that I plan on insulating my jacuzzi with before winter gets here.  Take off the panels, apply insulation in any fashion, replace, done. 

[MarKee]

The Spirit is very well insulated, you shouldn't need to add anything to it.  It has an icynene full-foam insulation, and a thick DuraCover with 2lb. density foam and a linear heat seal that seals off heat loss in the center of the cover.  If you ever lose power for more than a few days at a time, you will be surprised at how well that spa will maintain the heat.