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Old pool lights + new salt cell = rust stains on new surface

Posted by ladoladi (My Page) on
Sat, Aug 4, 12 at 10:14

Hi GardenWebbers,

You guys were incredibly helpful in the planning stages of our pool remodel, and I'm hoping you can help again.

In March, we had our old pool resurfaced with a quartz aggregate and re-tiled. We also switched out some old equipment: filter and heater, and we switched over to a salt cell. We've been doing a good job of maintaining our chemicals and salt levels. The SO takes a water sample every week to our local pool supply.

A few weeks ago we started noticing some rust-colored stains around the pool drain. SO thought maybe he wasn't putting in enough stain blocker, so he added more of that. Now the stains are everywhere, in the spa, along the seating area and the drain, and in the pool, around the drain and in other low spots... and we realized the 2 lights (one in the pool, one in the spa) which were never replaced are completely rusted out! So it would seem that's where the rust-colored stains are coming from, and I've no doubt it is the salt cell that rusted them out.

Our pool contractor NEVER mentioned replacing the metal lights covers. NEVER suggested they might in any way react with the salt cell. The lights were NEVER discussed, except in the context of removing them for the resurfacing and then putting them back on.

So, I have 3 questions for all of you knowledgeable folks out there:

1. Is this something we should hold our pool contractor accountable for?

2. Is there some way to clean the rust off?

3. What light covers should we use to replace the ones that are currently rusting away our new pool finish?

Thank you.

Follow-Up Postings:

RE: Old pool lights + new salt cell = rust stains on new surface

A replaceable zinc anode is generally set near the cell and tied to the bond wire to absorb stray currents, which is what I suspect is causing the rust.

A little steel wool in a small tub of shallow water is what I would try first. The tub and water will rinse the particles off so they don't get in the pool.


RE: Old pool lights + new salt cell = rust stains on new surface

Thanks, Scott. The pool contractor put a sacrificial anode in the skimmer basket. I don't think one was added near the cell.

I'm not so worried about the rust on the light fixtures as I could replace those if necessary. It's the rust stains on the NEW quartz aggregate surface I'm worried about.

RE: Old pool lights + new salt cell = rust stains on new surface

Rust means iron in the water of which there should be none. Its not hard to get test strips for. Are you on a well or municipal water?

If discovered, a sequesterant is needed so stains can't form. They are expensive but Cu-Later pouches in the skimmer will pull the iron as well as copper out of the water in a couple weeks or so while the sequesterant prevents further staining. If the finish is affected, an ascorbic acid bath (vitamin C in mass) may be called for first to get it back in the water and be held captive by the sequesterant and then the pouches.

Having an anode in the skimmer is good, especially if putting on at the pad is difficult. If the bond wire's potential for it isn't the same as the salt cells, i.e. there shouldn't be but maybe 1 ohm between the two, a small current can form. If the anode isn't connected to the bond, the stainless would attract the current because it is and the current has some place to go. With both connected, the current is absorbed by the anode which wears with time.


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