hydraulic cement, you can buy it at home depot

Renovxpt, thanks for the reply on the hydraulic cement which is what I suspected would be best but it is always good to have that confirmed. Are there any problems with drilling thru the gunite at this stage (before the finish is installed)?

papa- no problem with drilling a hole through the shell. Hydraulic cement is great, but I would encourage your plasterers to use water stops on all every shell penetrations....returns, leveler, drains, etc.

Natural one -thanks for the confirmation on drilling thru the shell but how is a water stop installed on returns or drains that are already in place? I thought water stops have to be in place prior to pouring the concrete or in this case, the gunite.

It goes around the joint where the hydraulic cement, pipe, and gunite wall are, both sides preferably. It acts as a membrane to keep the water from penetrating.

Scott

Typically Hydraulic Cements are expansive, so it's not a good idea to put them underneath plaster.

If I were to install an autofill in an exiting pool I would patch the pipe in with a sand/cement mix, and use the pool plaster for waterproofing.

Scott, thanks for your comments but I'm not sure how effective the water stop would be unless I'm missing something. Most of the water stop materials that I'm familiar with indicates that there needs to be a minimum of 2" of concrete on either side of the water stop. I don't think I'll have that thickness on the existing returns/drains. Is there a particular water stop material that you or natural one are referring to?

Racket, thanks for your input too. I agree that hydraulic cements are generally expansive but I thought only during the cure period. Once cured, they should be stable. Is it safe to assume that you have had experience where the hydraulic cement did expand and you had the plaster pop?

Thanks to everyone who have offered advice on this.