do I need sound isolution pads on bottom of monitors?

It depends fully on what kind of metal stands you have. If you think the resonances are affecting the sound, you most likely need to isolate either the loudspeakers from the stands or the stands from the floor.
 
Or are the stands attached to the wall? Or are they on the table? Are the speakers attached to the stands with screws or are they standind free? Hard to answer without knowing the situation.
 
If the stands have metal spikes serving as feet, you most ikely don't need any further isolation.

Thanks for the input..the stands are about 15 pounds and have an 18 inch triangular base with metal spikes that will set on carpet. Top is nine inch square with no spikes. I have a sub with my speakers so the speakers are not reproducing frequencies below 80.

Bristol_Jonesey
Do these stands allow you to fill their columns with a dense material such as sand?
 
Mine do and this adds to the mass/weight, allowing for even more isolation

+1, which was why I asked the question
 
I would suggest that you use the iso pads or Blue-Tak and six small coins three on each side.

I agree, it can't hurt, the only thing with the ISO pads I have now, my monitors sit a few more inches higher than I'd like... 

Do you NEED them? Probably not. I'm of the opinion that you're better off with the speakers in direct contact with a solid, heavy stand. Even if the pads actually do something useful (I've seen no hard evidence that they do, only anecdotal), I would think that having the tweeters at ear level is more important.
 
Lest I be accused of hypocrisy, I do admit to having pads under my speakers. However, because my stands are home-made I was able to build them a couple inches shorter to compensate for the pads' height. Also, my stands are wooden and perhaps a third as massive as a quality steel stand and 1/10th as massive as a sand-filled stand (or Jeff's concrete planter stands). Fortunately, they sit directly on concrete so even if the stand vibrates those vibrations stop at the floor.
 
Here's a thought. If your stands have spikes at the base, you might consider removing them. This would lower the speakers 3/4"-1". While I have some doubt about the efficacy of pads, I have no doubt about the uselessness of speaker and speaker stand spikes.