Slow pool leak - are these the causes?

[neen01]

We noticed we were losing water a bit towards the end of last summer and it definitely got worse this summer.
It did not leak over the winter so I know it isn't in the concrete part or bottom of the pool.
We just did the bucket test and the first day it was a decent difference of about 1/2 inch in and out of the bucket. It does seem to slow down - over night the next night was barely any difference.
I found a crack in the grout of the tile by the skimmer and also noticed when cleaning the skimmer baskets a possible location for a leak? There is the one hole that gets plugged in the winter and then another thing that has a white cap on it. There is foam/rubber stuff under that cap between the cap and the bottom of the skimmer that seems lose and old.
I took these two pictures. Do you think it could be one of these things?
If so, are these easy fixes for us to do ourselves?
If not, is there any way for us to figure out where the leak is without calling a leak detection place for hundreds of dollars?

 

[JohnT]

Chances are good the second hole isn't connected to the pool at all. If it is, it is for the main drain and shouldn't be plugged. Do you have a separate pipe for both the drain and skimmer at the pump?

 

[mas985]

There is a very good chance that it could be the skimmer grout. That is a fairly common leak location.

 

[neen01]

Chances are good the second hole isn't connected to the pool at all. If it is, it is for the main drain and shouldn't be plugged. Do you have a separate pipe for both the drain and skimmer at the pump?

We do have different pipes for the drain and each skimmer that all connect with handles so you can block off different ones.

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Is it hard to fix the grout? Is there a recommended grout?

 

[wjr75]

We have floor drains in our spa which had plugs in one of the un-used holes. One was leaking which I had resealed in the spring. I think our hydrostatic valve in our main pools main drain may have started a slow leak when the weather got cold. They pulled it out when I had the pool refinished in the spring and should have replaced it at that time. I will get it in the spring.

 

[mas985]

Is it hard to fix the grout? Is there a recommended grout?

Any pool grout will do. EZ-Patch is fairly common and usually pretty easy to find.