After replacing the various worn out parts in my tub, I have one last repair to do. My spa is leaking around the nipple in the equipment compartmentwhere the hose that goes to the input of the circulation pump attaches. I know it is not the hose that is leaking(new hose new clamp clamp tight.) because I can see the water going around the fitting and the water is dripping from the area between the shell and the fitting. I beleive the circulation pump gets it's water from the filter compartment. When I had the filters out when I drained the water from the tub, I noticed that some time in the past, some one had siliconed around the base of the where the filter attaches that is gray. (There are 3 filters in the filter bay on my tub) This repair must have worked for a while because the tub did not leak when I bought it used in November, but leaked once I got it home. The silicone has broken down, so it must not hold up to the heat and chemicals in a spa. What is the best way to repair this leak?

Best to replace the plumbing parts. All of it is 3/4" fittings and 3/4" tiger flex. There will be one or two 1/4" bleedline nipples tapped in here or there. Best to remove foam in that area, from under side and make repair, then refoam. There's a few of us HotSpring folk here that routinely help...let any of us know if you need something shipped. Only odd things you may not be able to easily find is a street elbow in 3/4" and the 1/4" bleedline nipples.

Thanks for the information! Is the best way to do this is to turn the spa on its side?

Yes.