Replacing a skimmer on an in-ground, fiberglass pool. How to seal and backfill?


New member
Feb 16, 2014
United States
My pool skimmer has been patched so much there's more putty than plastic, and it's leaking again. It's time to replace it. Fortunately, I have found the same size skimmer is still available. I know I'll need to saw and break out the concrete deck. I assume that I'll find the skimmer backfilled with dirt since the rest of the pool seems to have been done this way (unfortunately). When I replace it, what's the best way to seal the new skimmer to the fiberglass shell so it won't leak, and what's the best material to user for backfill so it won't shift? From what I've seen online, I suspect that I'll need to grind the back side of the shell to make it smooth and then use a lot of silicon caulk when I mount the new skimmer. I also have read that clean 3/4 inch gravel makes a good backfill for fiberglass pools, but I haven't seen whether this is specifically good to use around the skimmer.

If you have replaced a skimmer in a fiberglass pool, I'd really appreciate advice. I can't pay the $1800 price contractors are quoting me, and I've done enough PVC plumbing and other construction work around the house to be crazy enough to try this myself.



In The Industry
Nov 8, 2011
You shouldn't need to grind the back side of your shell. Make sure you get all the old sealer off before trying to attach the new skimmer. Use a high quality marine grade silicone to seal. Use a 3/8 - 1/2 " gravel not anything larger.


TFP Expert
LifeTime Supporter
Jun 5, 2012
DFW, Texas
Welcome to TFP!:handwave:

Most members have had better results using a polyurethane-based sealant vs. silicone for areas near and below the waterline.