Iron in the water is my guess. You need to test the levels of iron and calcium in addition to your alk and pH.

Scott

Scott - If iron and calcium are causing the stains, why aren't the other 3 spa jets and all 7 pool returns showing the same stains?

Steve

Without knowing how much water is passing each return, my guess is the spill jets get the most. Test and report your water results.

Scott

Actually, the spa jets have very little flow (valve barely open 99% of the time) compared to the pool returns; just enough for the spillway to flow.

Steve

With a single pump system, this is usually not the case, Steve. The return valve doesn't offer that great a granularity to allow this normally.

Scott

Iron & calcium both checked OK by my pool guy and Leslie's; with my hand I can barely feel any flow from the jets (just keeping the spillway going), while the returns are blasting away with no stains. I'm wondering if some re-bar is poking thru the PVC that drives the 2 affected jets, although I've noticed no leaks.

Steve

How do these spa jets differ from the rest? All I see is that you mention they are under the spillway. Normally a spillway is a damwall and is usually built (by default) thinner than the other walls of the spa (unfortunately). With plumbing in that dam wall as well, it has less concrete density to it, and can have weak points of coverage over plumbing and....you guessed it, rebar. It could even be as simple as tie wire holding the rebar that is out of the shotcrete and in the plaster. I've seen steel guys use tie wire to hold a spa jet in place as they steel a pool/spa. It's one of the reasons my preshotcrete inspection by my guys includes tamping down all tie wire and measureing for all shotcrete coverage over steel. Did you use a pool builder or did you go OB?

They're not under the spillway, they're on either side and look no different from the others except for the stains. The pool/spa and house were built in '02; we bought in '05.

Steve

You can determine if the stains are iron buy holding a vitamin C tablet on them for about a minute. They will go away if iron. Its been my experience that these stains are more likely to happen when the velocity of the water is slower and more frequently occur when the eyeball has been removed. Maybe its because the metal is more likely to come out of solution?

Metals, especially iron, comes out of solution with higher pH. The ascorbic acid of the Vitamin C tab puts it back in solution. The metal possibly being a rebar wire tie may have merit.

Scott

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