Stainless Steel Water Pot

cdchris1

Well-known member
Apr 28, 2016
71
SW Chicago/IL
#1
We had a copper spillover water pot installed with out pool last year. The pot is copper with a black power coating on the outside. The power coating has started to discolor and flake off. The manufacturer is going to replace it, but would like to replace it with a 316 marine grade stainless steel one. It too would have the black power coating on the outside, so it will look just like the one that we have. They said that the power coating adheres better to the stainless, but we ordered the copper initially because the manufacturer says on their web site that stainless is not recommended with a salt water pool. I was just concerned and wanted to get some opinions on using the stainless as opposed to the copper. Thanks in advance for you thoughts.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,680
Tucson, AZ
#2
316 is a marine grade steel although there are super-austenitic grades that are better at resisting chloride corrosion. 316L is a low carbon version that is better when pieces are welded.

Is this pot one piece or is it welded? Is the inside powder coated as well?

Even if it resists corrosion from salt water, galvanic corrosion is another possibility and the only way to avoid that is to use a sacrificial anode made of magnesium or zinc and either bolt it to the outside or bury it and connect the pot to it through a wire.

Believe it or not, copper is actually the better material in this case (as long as water remains balanced and pH is never acidic).

Can you just use a copper pot with a natural green copper patina on it instead of the black powder coating?




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cdchris1

Well-known member
Apr 28, 2016
71
SW Chicago/IL
#4
I suggested just going with a copper pot, but my wife over ruled me on that one. It is a welded pot with the powder coating only on the outside. We typically drain the pot when we are not using it, so the water would not be in it all the time. The pot is made by Bobe, and I must say their customer service has been good.

Is is there anything we should do to it, or any special way to clean it that would help?
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,680
Tucson, AZ
#5
I think it's going to eventually rust no matter what you do. And I think draining it and refilling it is going to speed up the corrosion process, not make it less because when the water in the pot dries out, it will leave behind concentrated salts at the surface. Chloride ions (Cl-) attack stainless steel no matter what you do and so you're just going to have to keep an eye on it. The powder coating on the outside might be better with the 316SS material BUT I think the inside is going to corrode over time. A regular copper bowl would be the best choice of material but I understand there are aesthetic factors at play.

All I can say is keep an eye on it. If you do notice any corrosion occurring, the best way to treat it would be to scour out the pot with Bar Keeper's Friend (powder or liquid). It's a mixture of silica powder (polishing agent) and oxalic acid. The oxalic acid is very good at removing iron oxide stains and helping to repassivate a steel surface. Naval jelly (mostly phosphoric acid) is also another excellent treatment for rusted surfaces as the phosphate forms an adherent layer on a compromised steel surface that is slow to dissolve away.

I wonder if there isn't something simple you could treat the inner surface of the pot with that would help to avoid the effects of the salt water....I'll have to think about. It's a shame they don't just powder coat the entire pot or do some kind of chromate conversion coating on the inside to help passivate the interior region of the pot.
 
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cdchris1

Well-known member
Apr 28, 2016
71
SW Chicago/IL
#6
Thanks for the help. You mentioned that we could possibly use a sacrificial anode as well. Could I connect a zinc anode to the copper bonding wire back by the equipment and achieve the same results? I wasn't sure about going from the stainless of the pot to the copper wire.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,680
Tucson, AZ
#7
Thanks for the help. You mentioned that we could possibly use a sacrificial anode as well. Could I connect a zinc anode to the copper bonding wire back by the equipment and achieve the same results? I wasn't sure about going from the stainless of the pot to the copper wire.
Sacrificial anodes need to be connected to the things they are protecting; the closer the connection the better. The pot would have to have a bonding lug on it where you could attach a short run of wire to a large piece of zinc buried in the ground (moist soil). Technically, you'd need at least as much surface area to the piece of zinc as there is exposed pot area you are trying to protect. Connecting a zinc rod to the bonding wire rarely works or protects anything.

I think you just need to keep an eye on it. There no simple fix here unfortunately.
 

Nursenini

LifeTime Supporter
TFP Guide
Sep 22, 2015
2,122
Bixby, Ok
#8
I'm sorry to hear about the flaking of the finish. We had a similar situation with our scuppers, also from Bobe. After install the beautiful finish started to bluster and peel off. Fortunately it happened while we were still under construction. Bobe replaced the scuppers (we went with hammered copper) and PB installed them. I had believed the flaking happened because the masons were careless with getting mortar and gravel all over them, piercing the finish coat and allowing the water from rain and power washing. Since it happened to yours also, maybe it's their fault nudging process...
 
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cdchris1

Well-known member
Apr 28, 2016
71
SW Chicago/IL
#9
So we finally got the new pot installed last week and unlike what they told us, the entire pot was power coated, inside and out. I'm guessing that this will better than having exposed stainless steel. We still plan on draining it when not in use, so will the residual salts cause any problems with the power coating?

As a side question, after the new pot was installed, we put some pea gravel in the bottom and then filled it with white beach stones. The stones were kind of dirty and it all washed into the pool along with flushing the fountain pipe that had sat stagnant for 6 weeks. Could this have caused a small algae bloom? I noticed a couple of days after we ran it that my chlorine dropped, but not below minimum. I cranked up my SWG a little and did not think much of it. The next day my FC was below minimim and the water was a little cloudy. I then SLAM'd and it has been fine since. Just wondering if starting up the new pot could have caused this or if I have something else going on.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,680
Tucson, AZ
#10
So we finally got the new pot installed last week and unlike what they told us, the entire pot was power coated, inside and out. I'm guessing that this will better than having exposed stainless steel. We still plan on draining it when not in use, so will the residual salts cause any problems with the power coating?

As a side question, after the new pot was installed, we put some pea gravel in the bottom and then filled it with white beach stones. The stones were kind of dirty and it all washed into the pool along with flushing the fountain pipe that had sat stagnant for 6 weeks. Could this have caused a small algae bloom? I noticed a couple of days after we ran it that my chlorine dropped, but not below minimum. I cranked up my SWG a little and did not think much of it. The next day my FC was below minimim and the water was a little cloudy. I then SLAM'd and it has been fine since. Just wondering if starting up the new pot could have caused this or if I have something else going on.
Nice to hear that you got this resolved. The powder coating, as long as it is not cracked or mechanically abraded, should last a long time and not be affected by salt. The pea gravel and stones should have been washed and soaked in bleach for a day as you can not control what they will bring in to the pool in their raw state. That was likely the cause of the water cloudiness and possible algae problem. Just SLAM it, and you'll be fine.

As for the pot itself, I would suggest you schedule it to run several times per day. It won't take much, maybe 15-20min every couple of hours until sundown. This way, the pot and it's contents stay flushed with chlorinated water and you don't have to worry about algae growth.
 
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cdchris1

Well-known member
Apr 28, 2016
71
SW Chicago/IL
#11
Thanks, good to know about the power coat. As I saw the dirt coming off the rocks and flowing in to the pool, I though, "Yea, we should have washed those first". We keep our auto cover closed most of the time, so I do not want to automate the pot. I do make a point of running it every couple of days at most and that is also why we drain it when we are done with it.