Swimming Pool Blog
by Rob Cox May 9, 2015
The Sylvan pool of the previous era, before they became Anthony Sylvan Pools in 1996, was a solid piece of pool construction, with minor exception. One such exception, and problem for Sylvan pools built in the 80's and 90's, was the use of Flex Pipe, aka Flexible PVC pipe to connect the last few feet of pipe from the skimmer to the main pipe trench. Using flexible PVC allowed for faster and easier connections without much measuring and use of costly PVC fittings.
However, Flex pipe has a few problems when used in this manner. One, Flexible PVC has certain chemicals in it which attract earwigs or termites which come to feast on the soft delicacy. Secondly and more commonly, the soft nature of Flex pipe is easily damaged from chlorine. And what do people do? They put chlorine tablets in the skimmer.
Even without putting chlorine tablets in the skimmer, over time the interior of the flex pipe becomes swollen and begins to look like a clogged artery. This causes more pressure on the walls of the pipe as the pump tries to suck the water through the smaller opening, which actually and eventually causes the pipe to crimp and collapse.
Weird stuff, right? The Sylvan company had no idea at the time that this could be a possiblity, and I don't think that they would warranty this skimmer repair. If your pool was built by Sylvan pools from 1976 to 1996, it's a good possibility that there is flex pipe under the deck, just a small section, about 3-5 feet in length, running in between the bottom of the skimmer, and the rigid PVC pipe laying in the trench.
STEP ONE: CUT THE CONCRETE
If your deck is only 3-4 feet wide, you can elect to tunnel under the deck. Although it seems like more work, it can be easier overall than removing and replacing a concrete section. If there is 4-5 feet of deck however, you are better off cutting a hole in the deck, just behind the skimmer. Make it large enough to work, at least 3 ft x 3 ft in size. Cutting concrete can be done with a 7" grinder or with a larger 12" or 14" cut-off saw, aka chop saw. Or, you can do as done here, and use a small jackhammer to punch a bunch of holes in the deck, and then break up the slab with a sledgehammer. Our subject first cut a small pilot hole, then realized that he needed to go much bigger.
STEP TWO: DIG DOWN AND UNEARTH THE PIPES
Fortunately, the digging should not be too hard, should be solid soil without large rocks. As you near the edges of the skimmer, you may encounter a wall of concrete around the skimmer. That's OK, keep digging past it, about 2-3 feet down, until you have removed all of the dirt from around the pipes, and located the section of flex pipe that was used. Keep digging until you unearth all of the flex pipe. In this case, we found that rigid PVC or hard PVC was used to connect to the skimmer but only for about a foot, then a 5 foot connector piece of flexpipe was run between the skimmer stub pipe and the main skimmer line laying in the trench.
Looks OK so far, except for that strange angle of the flex pipe behind the rigid pipes. Below is what was found hiding behind the pipes, a crimped and collapsed flex pipe used on a Sylvan Pools skimmer, due to pipes weakening over time. Not surprising that the flow rate was literally zero in this skimmer.
STEP THREE: CUT OUT THE FLEX PIPE
Find both ends of the flex pipe, so you can remove it all. Dig out underneath and behind the area to be cut, to make room for the sawing motion. Use a hacksaw or a PVC saw, or a piece of picture hanging wire with two duct tape handles, for really tight spaces. Try to make straight cuts, and clean the pipe after with a wet rag and then sand the pipe with sandpaper or emory cloth.
STEP FOUR: REPLACE THE FLEX PIPE WITH RIGID PVC PIPE
Measure twice, cut once! Use as few fittings as possible, except when using two 45's in place of a 90° fitting. You will need deep socket couplings and 45's, as shown, which glue up to 1.5" deep. Use only schedule 40 PVC pipe and pressure fittings; don't use drain fittings or schedule 20 pipe.
STEP FIVE: BACKFILL, TAMP, WATER AND TOP WITH GRAVEL
Support your pipes underneath with bricks or blocks if needed, and pack dirt around the pipes to fill the hole again. Tamp as you go, being sure to fill all voids. Fill the hole with dirt up to about 4" below the deck level, tamp again and then soak with water several times to help the dirt settle. Top with bluestone gravel (the regular stuff) up to the bottom of the existing deck around the hole.
STEP SIX: PLACE JOINT FOAM AND POUR NEW CONCRETE
Before pouring, clean up the edge of your hole if necessary so the edge is fairly even. Use liquid nails or double sided tape to secure flexible foam expansion joint material around the inside edge of the old concrete. This foam material will create an expansion joint between new and old concrete. You don't have to make an expansion joint, but if you don't, expect a crack to develop between new and old slabs.
Mix up your concrete in a mixing tub, 1-2 bags at a time. Most holes will take 4-6 of the 80 lb. bags of Sakrete®. After it's in place, use a 2x4 cut to size as a float, to push the concrete into all corners and voids. Keep adding concrete until the level is at or slightly higher than, the surrounding concrete. Hit the surface once with a flat trowel, and then drag a broom lightly across the surface to create some texture.
BEFORE YOU GO RIPPING UP THE POOL DECK...
If your pool skimmer loses its suction, or anytime a skimmer is not working, don't assume that (a) there is flex pipe underground, and (b) that the pipe is crimped or collapsed. If the suction has dropped off considerably on just one skimmer, check some things first. Namely, the skimmer valve could be broken, or the pipe could be clogged. Also keep in mind that skimmers that are further away from the pump will have less suction than skimmers located closer to the pump. Skimmer valves can be adjusted to compensate, or a throttling plug or plate can be used on the closer skimmer, as a flow reducer.
Use a Drain King® to try and blow out a clogged skimmer line (from the pump, back towards the skimmer), which could be from leaves, acorns, golf balls, plugs or dive sticks, just to name a few possibilities. A plumber's snake can also be used to test the skimmer line, or clear a line (pipe), although it's hard to push through a 90° fitting. Poor skimmer suction is also caused by obstructions on the pressure side, like clogged impellers or pump baskets, a dirty pool filter or closed, partially closed or broken return valves.
If you do own a Sylvan pool from the era of '75-'95 (and not just Sylvan, but other inground pool builders also used Flex pipe during this era), you may have this type of skimmer problem in your future. Don't sweat it, it's a weekend job for you or for your pool repair person.