Sequence of chemicals and possibly any effects on what happened to screws at light.

[Catanzaro]

Each day I dose the pool with approximately 3ppm of liquid chlorine, and adjusting every few days if necessary. On average, every 4 days, I have to add 10 oz. of Muriatic Acid to lower my PH down to 7.5. The color is usually between 7.6 & 7.8. Ironically the PH this year started at 7.2, raised it up slightly to 7.6 with 1/2 box of Borax. After this, it seemed like my PH was rising slowly until it was over 8.0-8.2. Because I could not see the difference of the colors, I always thought I was around 7.8 and not near 8.2. I started using dry acid and eventually switched to Muriatic Acid. Stabilizer increased as needed from 30-50 in the beginning of the season & now down to 40. The TA was at 140 in the beginning of the season and now down to about 100 because of all the acid additions. My goal is to get this down to about 80 to determine if the PH will hold. If not, I may add borates or remove the 4 rotating aerating heads that create a lot of little bubbles. This may not be accomplished this year. CH has gone down from 200 to about 125.

Question: Can the addition of liquid chlorine, mixing for 30 minutes and then muriatic acid in the deep end (in front of the return) mixed at the same time cause any type of electrical charge, or "electrolysis"? This is a non SWG pool.

I had an issue with rust dripping on the screws near the light niche. The electrician is coming to test everything out over the next few days with regards to the bonding and grounding of pool and lights, etc. The light has not been used at all and the second set of screws have no apparent rust on the heads. Once the electrician is done, I will turn on the light for at least 4-6 hours with filter running to determine if this is causing any problems with the screw heads. They were not rusting, just rust accumulation and/or dripping on the heads.

I was reading something about SWG pools, and all weird things can happen when the SWG is running, creating electricity and acid is added, combining with alkaline pools, etc. I am wondering if any of the combinations in my pool could have caused this? I understand that this could be far fetched, and maybe I am overthinking this whole process. Should I be adding the Muriatic Acid in any other way?

Hayward, who kindly sent me new screws, claims that they are stainless steel and something else is causing this problem and not the screws. Even though, the second set of screws were sprayed with a marine spray, there is no apparent rust that could have been caused by Galvanic Corrosion.

Thank you.

 

[tim5055]

Wow, you have me on this one....

I,admit there are many issues that only Chem Geek understand, but you got me. I have no SWG (Stenner Pump) but I,add chlorine and acid all the time. No rust/corrosion on my light screws at all.

 

[chem geek]

No, the chemicals you are adding are not creating any sort of electrolysis nor stray currents. The acid if not properly mixed with the pool water can of course corrode metal but that's a direct effect of low pH.

It's more likely that your screws are not made of corrosion resistant stainless steel (i.e. they may be Type 304 stainless steel instead of 316). If the light ring were made of better stainless steel then that can promote galvanic corrosion due to the contact of dissimilar metals exposed to the water. All stainless steel is not created equal. Did Hayward say specifically what grade/type of stainless steel was used for the screws?

If you want to protect all the metal in your pool, even if it is of poor quality, you can electrically connect a zinc sacrificial anode to the bonding wire and bury it in moist soil. This assumes that your light is connected to the bonding wire (the screws should be electrically in contact with the light ring.

 

[Catanzaro]

No, the chemicals you are adding are not creating any sort of electrolysis nor stray currents. The acid if not properly mixed with the pool water can of course corrode metal but that's a direct effect of low pH.

It's more likely that your screws are not made of corrosion resistant stainless steel (i.e. they may be Type 304 stainless steel instead of 316). If the light ring were made of better stainless steel then that can promote galvanic corrosion due to the contact of dissimilar metals exposed to the water. All stainless steel is not created equal. Did Hayward say specifically what grade/type of stainless steel was used for the screws?

If you want to protect all the metal in your pool, even if it is of poor quality, you can electrically connect a zinc sacrificial anode to the bonding wire and bury it in moist soil. This assumes that your light is connected to the bonding wire (the screws should be electrically in contact with the light ring.

Thank you Chem Geek!

For starters, Hayward did not answer my question via e-mail on what type of stainless they are using. It is very possible that the PB used aftermarket screws to save themselves some $$$ (who knows). I am still convinced this all has to do with the light (first time it was really used in over 1 year). The light niche is plastic, the light trim pieces are plastic, and maybe this could rule out "Galvanic Corrosion". Once I get a hold of Hayward, I will find out if the screws are threaded into the light nice or metal frame. I believe the screws do not touch the walls, and only the niche is attached to the metal frame. Even if the walls, combined with the screws and water created rust, chances are that this would drip on the liner and not on the screw heads. Last year I had a minor cut in the liner that had small traces of rust drip up on liner. It was patched up under warranty and the spot was easily removed with Vitamin C. I am kind of ruling this out as well.

Definitely not chemistry as "I have learned from the best" at TFP.

The issue with the "zinc sacrificial anode" to the bonding wire is that they are at the frame of the pool with a tremendous amount of concrete around the pool (9 ' on diving board - light area). Everything was bonded together, which includes the diving board, the steps, rails at stairs and light. Township passed inspections and they are very thorough. Could a wire have disconnected during backfilling (possibly), but I doubt it.

Unless there is a way to go to the filter area, where the light switch is grounded-bonded, then I can easily bury a wire in the ground), if not no good. One other thought is that we have underground wiring here in NJ, but the wires are no where near the light outside.

The true test is after the electrician leaves and I turn on the light again. He should be here either today or Tomorrow. If not, definitely by next week. If this happens again, then clearly this is electricity causing the issue.

Gentlemen, thank you for your quick response.

 

[chem geek]

So if the light ring is plastic, then yes you should find out if the metal screws are screwed into a metal frame and if that frame is connected to the bonding wire. Bonding by itself would not reduce corrosion, but would give you the opportunity of easily protecting the metal from corroding as fast by using the zinc sacrificial anode electrically connected to the bonding wire and buried in moist soil. Since the pump should also be connected to the bonding wire you should be able to extend the wire from there for your anode. Of course, if the bonding wire to the light is broken or not connected at all, then it won't help, but you should be able to test this with a continuity or resistance meter (with very long wires for your test leads!). And yes, the electrician should be able to tell you what's going on electrically with the light, including whether it is bonded and whether the screw connects to such bonding.

 

[Catanzaro]

I actually was able to reach Tech Support at Hayward. They claim the 10 screws go through the metal. In reality, the 10 screws actually are threaded into the light niche housing. It can not be as the liner is raised off the wall near the Niche Face Plate. Hard to tell but I was told it was wall, gasket, liner and then face plate. Also was told that there is another gasket over the liner, which I do not see (hard to tell). If the screws went through the wall, then you would be able to see the screws as there is a slight gap (maybe 1/4") that you place a small ruler and hit the screws (not happening).

Amazon.com : Hayward SPX0507A1 Niche Face Plate for Underwater Lights, White : Swimming Pool Lighting Products : Patio, Lawn Garden

As you can see in the diagram below, the screws are going into the light niche (because they are threaded). It would be nearly impossible to have the screw removed and insert multiple times onto the pool frame.





F is the Pool Panel and G is the back up Ring. The back up ring has threads where the screw enters. Yes, the screw would go through the panel, but it is inside the ring. There could such a small amount of water, which is possible.

I will allow the electrician to handle this one. Way beyond the scope of my knowledge. Thank you.

 

[Catanzaro]

So if the light ring is plastic, then yes you should find out if the metal screws are screwed into a metal frame and if that frame is connected to the bonding wire. Bonding by itself would not reduce corrosion, but would give you the opportunity of easily protecting the metal from corroding as fast by using the zinc sacrificial anode electrically connected to the bonding wire and buried in moist soil. Since the pump should also be connected to the bonding wire you should be able to extend the wire from there for your anode. Of course, if the bonding wire to the light is broken or not connected at all, then it won't help, but you should be able to test this with a continuity or resistance meter (with very long wires for your test leads!). And yes, the electrician should be able to tell you what's going on electrically with the light, including whether it is bonded and whether the screw connects to such bonding.

If you want to protect all the metal in your pool, even if it is of poor quality, you can electrically connect a zinc sacrificial anode to the bonding wire and bury it in moist soil. This assumes that your light is connected to the bonding wire (the screws should be electrically in contact with the light ring.

Chem Geek:

Advanced Question:

The screws go through the light niche ring, gasket, liner, gasket, and through G235 Galvanized Steel Wall that is coated with Galvanized Steel Zinc and Copper Coated Steel. (This is what the PB describes the walls as). The screws are threaded into the light niche with an accessory behind the wall and in the dirt.

The electrician tested everything with the grounding wire at the filter-pump and determined that everything is grounded and bonded correctly to the frame of the pool. He tested the ladder, diving board, hand rail. Everything checks out. Also put some testing equipment in the water and stated there was no electricity. The electrician ran a wire from the ground (copper wire) at the equipment area. I have no idea if the bonding wires are all connected to the same area. Assume they are. He never had to add a Zinc Sacrificial Anode.

I am assuming the bonding of the metal frame and components are running back the equipment area and that is the wire out of the ground. I can take a picture tomorrow as it is dark now and send in the thread. I am somewhat handy. Assuming I purchase Zinc Sacrificial Anode, how is it connected to the bonding wire? Are there special "jumpers" or "accessories" needed, or should I allow the electrician handle this? What type of wire should I be using for the Anode? And how far should it be buried from the equipment pad? There is about a 20' area between equipment pad (this is where the sand filter, pump, and plumbing is) and the concrete. There is a 9' gap between concrete and pool water. Assuming this could help further deteriorate the new screws.

Can you recommend a Zinc Anode and does it have to be buried in the soil? Are there any that can stay out of the ground? What ever works best, I will do.

Hayward finally sent me "Stainless Steel" screws and they seem to match the other screws on the returns. The PB changed the white plastic trim pieces and upon inspection, I did not see any rust on the liner. There were 10 tiny holes in the liner where the screws go. Whether the old screws were defective or galvanic corrosion occurred, I would like to finally put this to rest. I mentioned to the PB if this happens again, the water will be drained below the light to determine if there is an issue with the panel as liner will have to be peeled back.

Thank you.

 

[Catanzaro]

Inline Zinc Anode 2 In 0173-5


I found this on line. Can this be attached to the 2" plumbing and connected to the ground-bonding wire. Sure looks like this is a perfect fit. My plumbing is right there and parallel to the ground.

 

[chem geek]

The inline zinc anode will add zinc into the pool water. It would be better to instead bury the anode in moist soil so as not to add zinc to the pool. The inline anode is not a disaster and because it is electrically connected to the bonding wire it would work.

 

[Catanzaro]

The inline zinc anode will add zinc into the pool water. It would be better to instead bury the anode in moist soil so as not to add zinc to the pool. The inline anode is not a disaster and because it is electrically connected to the bonding wire it would work.

Yes, this does touch water. I read another post with comments and I would have to drill a hole in the plumbing. Not happening. I will continue to search for a Zinc Anode that can be buried.

I am trying to understand if the path is through the copper wire and what the process really is. Any thoughts on what you would purchase and where?

Google

Corrosion Grenade Clamp-on Corrosion Inhibitor Zinc - FreshWaterSystems.com

I will also call "West Marine" in NJ. They are a boating specialist and may have something there as well.

 

[Catanzaro]

Attached are pictures of Sacrificial Zinc Anode. Connected to bonding wire and will be buried in ground tomorrow.

 

[chem geek]

Yes that looks correct. If you measured the voltage between your bonding wire and another area of moist soil (i.e. to a regular "ground") you should find that the zinc is imparting a small negative voltage onto the bonding wire. This is how it inhibits corrosion by increasing the required energy for corrosion of metal (conversion of neutral metal atoms into positive metal ions).

 

[Catanzaro]

Yes that looks correct. If you measured the voltage between your bonding wire and another area of moist soil (i.e. to a regular "ground") you should find that the zinc is imparting a small negative voltage onto the bonding wire. This is how it inhibits corrosion by increasing the required energy for corrosion of metal (conversion of neutral metal atoms into positive metal ions).

Thanks Chem Geek:

I will not be doing any other testing. Way beyond my knowledge.

Quick question. Hayward stated possibly adding one of these at the light. Do you feel it is extra insurance or not needed at this point? And does corrosion only occur when electricity is on? Meaning, either light is on or filter is running? This is what I remember reading.

Should I bury the whole wire including the Zinc Anode or just the Zinc Anode? If so, how deep (3") sufficient?

Thanks a Million!


Pool Tool Zinc Anode Pool Light Protector

 

[chem geek]

Up to you. Technically a zinc anode on the bonding wire should protect everything on that bonding wire. The voltage protection does fall off if some items along the wire are trying to corrode so yes putting one closer to the light would help the light more.

Corrosion has nothing to do with the items being on. You don't need any power to be on for there to be corrosion. The filter can be off and the light off and it will corrode just as fast. Corrosion is not occurring because the units are powered. It is occurring because of the chemistry between the water and the metal.

You only need to bury the zinc anode, not the wire connected to it, but it's OK to do so if you need to do that to bury it into moist soil. The depth doesn't matter as much as being in soil that is somewhat moist so probably in an area that gets irrigated or has a natural water source.

 

[Catanzaro]

Chem Geek:

I do not know how to thank you enough. I do not want to be removing the light, if I do not have to. Additionally, I am not concerned about spending a few extra dollars for a piece of mind.

1) Inter-Fab Anode Sacrificial Zinc Rail Protector. If I put one of these by my ladder and one by my hand rail, will this help? Of course, I can not hard wire these with copper # 8 wire.

Amazon.com : Inter-Fab ANODE Sacrificial Zinc Rail Protector : Swimming Pool Ladders : Patio, Lawn Garden

2) More importantly, please see pictures below. I will try to be simple as possible.

When they bonded the JIG for my diving board, it was permanently installed in the cement. Because I failed the township inspection, the mason had to cut the 2 jigs, leave one exposed, and use a epoxy kit, then use special jumpers to create the bonding loop, which of course ends. The diving board has 4 supports, instead of 3.

Considering the screws are near the frame of pool, and right under the diving board, does this make sense? That is, add another Zinc Anode in the diving board and attach to the existing copper wire? (It will not be visible). It is a simple quick fix. I have extra copper wire and another $20 will not be too much. I like having extra insurance to protect myself.

 

[chem geek]

Again, up to you, but note that the anode for the link you gave says "must be placed in the water", which is correct -- it has to be either in the water or connected to a wire and buried in moist soil. If you attach it directly to the ladder underwater, then when the zinc corrodes it will release zinc ions into the pool. As I wrote earlier, it would be better to have the zinc corroding into your soil rather than the pool so that you don't build up zinc ions in the pool. You can have up to 545 times as much zinc in the pool compared to copper before it will precipitate or stain so the risk is low, but in general we try and avoid adding unnecessary chemicals to the pool to avoid side effects. So again, up to you.

As for the post coming out of the hardscape, assuming the one that came up is still bonded, then it would be another attach point for a wire to a sacrificial anode, but you don't have to overkill this. I wouldn't have wire over your hardscape as a potential trip hazard, if that's what you were talking about doing.

 

[Catanzaro]

The hardscape is inside the diving board base and I will not see it as the diving board is on top. Not in a moist environment, but hidden. I will only add another anode to bonded jig, etc. the electrician tested and said it was bonded . Assuming the Anode is not in moist soil (inside the diving board base), will this still work? , Probably not as effective and will degrade faster. This is fine, as I can inspect yearly and replace as needed.

Thank you.

 

[chem geek]

If the anode is just in open air or in dry soil, it won't work well because any zinc that degraded into ions won't be carried away so it won't maintain the negative voltage on the bonding wire needed to protect other metal from corroding. It would degrade more slowly, not faster. If you find that your zinc anode degrades faster, that means it is protecting the other metal in the pool -- sacrificing itself.

 

[Catanzaro]

If the anode is just in open air or in dry soil, it won't work well because any zinc that degraded into ions won't be carried away so it won't maintain the negative voltage on the bonding wire needed to protect other metal from corroding. It would degrade more slowly, not faster. If you find that your zinc anode degrades faster, that means it is protecting the other metal in the pool -- sacrificing itself.

Thank you Chem Geek:

I will put this to rest. With modern pools, one would think that "screws" should just not rust, especially if chemicals are on track.

Only option I have is a little Zinc Anode at light (but that is in the water), and for now this will not occur as I understand about Zinc in water. However, I did bury the Sacrificial Anode in the soil (about 3"), and put a White Round Cap on top, out of the ground in where I fill this up with water to keep moist. Every few days, I will add a little bit of water there. Only in the winter when the ground freezes, this can not occur.

No need to respond unless I need to bury the Zinc Anode deeper than 3" (from the top), bottom is about 4.5" and the connection is stable. So far no rust has occurred on the screw heads.

The panel was already cut out by the manufacturer and there was a spray applied before the light niche. This is clearly a mystery. Take care Chem Geek. You are truly an asset to the TFP Community.

 

[chem geek]

Good screws generally do not rust, but manufacturers insist on using cheap products so lower quality stainless steel such as 304 instead of 316 or 316L. Also, if one is not consistent in using the higher quality stainless steel, then if it is in contact with lower quality metal, galvanic corrosion will accelerate the corrosion of such lower quality metal near the point of contact. The screws in my light rings have not corroded and they are now 12 years old. I have no sacrificial anode.

The little Zinc Anode at the light in the water WILL work if the anode is electrically connected to the light metal if that is connected electrically to the screws. When I said not to put the zinc into the water it wasn't because it wouldn't work but rather to avoid adding zinc ions to the water.