where the steps meet vinyl


May 25, 2010
I've had a pool for about a month, this site has made maintaining it extremely easy so far, Thanks!!

I appear to have fiberglass steps going down into my vinyl pool. The caulking between the two seems to be wearing off and I see what appears to be green moss and some black stuff. My CC is .5 and the water is as clear as I've ever seen it, but the caulking has me concerned. Should I scrub it the best I can and then try sealing it with some silicone or something? Does that work under water? or do I wait until closing time and drain the pool... 15K gallons... :(

Any advice would be super!!

My number atm are (some of them aren't perfect, but I'm working on it) -

FC -4.5
CC - .5
TA - 220
PH - 7.6
Cal - 460
CYA - 20


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
It's pretty common for algae to find it's way into little cracks and places where the chlorine cannot get to it. A soft bristle brush will usually get in there and clean it out. It'll come out into the pool where the chlorine can kill it.

Always keep your chlorine at the suggested levels and it will normally prevent it but it's common for it to find some hidey places that take some extra work.

Caulk will not work underwater.


TFP Expert
LifeTime Supporter
Mar 29, 2007
Coastalish 'down easter'
Welcome to TFP!!

The black you see could well be the gasket that helps make the watertight seal at the steps :cool:

Glad you realize the chems could use a little tweaking :goodjob:

We'll be here for you if you have any issues!
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