Magnesium anode to prevent rust ?

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S

Sdhb

Well-known member
Jul 20, 2023
109
Canada
Pool Size
54509
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-9)
I just replaced my ladder rails and bolts with MG316 versions of the same due to rust buildup that kept occurring at the drill points where the bolts secure the ladder steps. Ladder guy advised that I might have a problem with galvanic corrosion, or high salt. Suggested the use of an anode to prevent rusting the new rails.

My salt has been running a bit high 3800/3600ppm (but not ridiculously high) so I'm discounting that more or less. I also tried testing the water for stray current with a multimeter and got something in the neighborhood of AC 0.012 and 0.0 DC, even with everything running (pool lights, pump., landscape lighting etc) so I'm thinking that is not a concern either. I'm all ears for any other suggestions.

Short of that, I picked up this cheap anode from Princess Auto and thought about cable-tying it to my ladder rail directly. Not sure if it would help but figured it wouldn't hurt? Unless it might. Would love to hear some thoughts about the issue and this possible solution. I am also seeing what looks like the start of some rust on pool light bolts that were replaced several years ago. Nothing crazy but it's starting for sure I think. My Pool Math history is posted here if curious about levels over time. Thanks!

 
Sdhb said:
I just replaced my ladder rails and bolts with MG316 versions of the same due to rust buildup that kept occurring at the drill points where the bolts secure the ladder steps. Ladder guy advised that I might have a problem with galvanic corrosion, or high salt. Suggested the use of an anode to prevent rusting the new rails.

My salt has been running a bit high 3800/3600ppm (but not ridiculously high) so I'm discounting that more or less. I also tried testing the water for stray current with a multimeter and got something in the neighborhood of AC 0.012 and 0.0 DC, even with everything running (pool lights, pump., landscape lighting etc) so I'm thinking that is not a concern either. I'm all ears for any other suggestions.

Short of that, I picked up this cheap anode from Princess Auto and thought about cable-tying it to my ladder rail directly. Not sure if it would help but figured it wouldn't hurt? Unless it might. Would love to hear some thoughts about the issue and this possible solution. I am also seeing what looks like the start of some rust on pool light bolts that were replaced several years ago. Nothing crazy but it's starting for sure I think. My Pool Math history is posted here if curious about levels over time. Thanks!

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Wont help anything, and may add zinc to the water as it degrades.
 
I figured Lol. Any tips to prevent rust? I don't think it's an issue with my pool chemistry... As far as I can tell.
 
ACHSHUALLY .....

A bolt on magnesium anode would work well enough - try one of these and physically bolt it on the ladder frame.

Hull Magnesium Anodes – Bolt-On | BoatZincs.com

Hull Magnesium Anodes – Bolt-On | BoatZincs.com | America's Superstore for Marine Anodes
boatzincs.com boatzincs.com

If there is any galvanic corrosion between the steel metal frame and the anode, the anode will preferentially dissolve. Magnesium won't affect the pool water at all.

Can't hurt.

The TEF Gel anti-sieze lubricant is just a teflon polymer gel that doesn't harden or dissolve away. It can be used on all the screw hardware to help protect them from corrosion. You might want to pull the ladder every season and take it apart to clean it up really well before storage for the winter. That can help a lot to avoid corrosion from saline water conditions.
 
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Perfect thanks. Those look better suited but a bit pricey compared to the cheapy I got at princess auto. I'm assuming it will achieve the same thing.. Assuming they do anything at all as long as it is in direct contact with the rail.
 
Sdhb said:
Perfect thanks. Those look better suited but a bit pricey compared to the cheapy I got at princess auto. I'm assuming it will achieve the same thing.. Assuming they do anything at all as long as it is in direct contact with the rail.
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You can’t just zip tie it to the rail. It either has to be welded on or bolted on in a such a way that the contact between the metals cannot be interrupt. So whatever you choose to use, the contact has to be really really solid. Otherwise it will just build up a passivation later between the metal surfaces and then nothing will happen.
 
JoyfulNoise said:
You can’t just zip tie it to the rail. It either has to be welded on or bolted on in a such a way that the contact between the metals cannot be interrupt. So whatever you choose to use, the contact has to be really really solid. Otherwise it will just build up a passivation later between the metal surfaces and then nothing will happen.
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If the anode is cable tied sideways with the cable tie on the outside of both anode and rail, wouldnt that be in contact, enough? Just trying to understand how a bolted version would be any different. Maybe I am not understanding. Unless the idea is to bolt the anode through the rail? In which case I'm hesitant to drill any new holes that might promote rust.
 
Bolting means you have a hole drilled into the magnesium slug and a receiving hole in the steel rail. The bolt will make tight, intimate contact to both metal parts. When bolting an anode into place, you use sufficient enough force/torque such that the metals crush in to one another a bit. In other words, the two metals are in “intimate” contact and there is no way for anything to get between them.

A cable tie, even a metal one, is only going to push the two pieces together and give weaker contact. Eventually, the cable tie will loosen up or a sufficient enough amount of oxide will build up in the crevice between the two metals that contact will be lost or degraded.

The ideal situation would be the two metal surfaces welded together. Anything short of that is less desirable. You can try the cable tie idea if you want, but I doubt it will be effective over the long term.
 
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