Brown Staining On Inner Walls of PVC Pipe

[Dirk]

Fill the pool with soft water how? With a residential water softener? That would be quite a project. They only put out so much soft water before they have to regenerate (based on how hard your water is). You'd have to monitor it and work the system accordingly. Not sure it'd even be possible, especially if it regenerates on schedule, not on demand.

How is it that you're on a well in Miami?

Maybe fill the pool with enough well water to get you to 350 (using your volume and Pool Math), then let the rain do the rest? Assuming your tile finish can stay out of water indefinitely?

Or fill with well water then do replacements with rain water?

I know I'm missing something in this saga. I was just following along about the mystery stain. Interesting stuff, especially its apparent selective nature. Weird...

 

[Hanstb]

Thank you Dave, the dogs love the pool too!

Dirk,

I'm at a loss to explain the selective nature of the staining, I'm not 100% certain what's causing the stains in the first place, the only thing I can think of, and it's a 'swag' at best, is that different pressure and flow characteristics in the suction vs the discharge plumbing influences whether the sediment accumulates or not, plausible, yes, no, maybe...

Our primary residence is in Miami, this pool is at our second home and is well fed, sorry for the confusion.

We have a dual tank water softener capable of treating 40 gpm (our pumps can exceed that flow), one tank is in service while the other regenerates, the system switches tanks automatically based on total flow. Filling the pool with soft water would require keeping an eye on the brine tank, but it's very doable. That said, I can't see the advantage, there does not appear to be anything in the well water that would cause issues with the pool going forward, I need only blend in softened water to achieve the target CH.

We have an event planned that puts a hard deadline on completion of the work being done including the pool, so rain water is a no go.

Barring some new information, this is what I have decided to do: I am going to replace as much of the stained pipe as I can, probably about 5 linear feet from inside the pool shed, then put the pool back in service and wait a while. Once the pool has been filled for several months, I will open the plumbing back up and see if the staining returns to the new pipe, if it does, I'll reevaluate, if it does not, I'll call it good.

 

[Dirk]

Yes, it is a mystery. I too had the thought that it is somehow pressure related, but don't know enough about that to have given an intelligent comment. I'm assuming the force on a pipe exiting a pump is more than on one entering, helping to embed it somehow? That stuff is way beyond me.

Nice softener system!! Blending seems like the way to go. Run a hose from both well and softener and see what'cha got about half way up. Continue one or the other as needed? Something like that? I set up my auto-fill connection so that I can blend street and soft water, so I'm with ya there.

Here's a tip I like to offer when I can catch someone with an empty pool. Put some sort of flow meter on the hose as you fill. You'll end up with a much more accurate volume number than you can usually get doing dimension math. The more your willing to spend on the meter, the better the number you'll get. I paid about $60 for mine, which I repurposed later so it was money well spent. My volume is accurate to about 1.5%. They sell much cheaper flow meters at Lowes/HD, but you kinda get what you pay for. Nice to have a good number when it comes to dosing.

Sounds like you have it all covered with the replacing and the revisiting. Good luck!

Oh, your Location should match where your pool is, at least in climate, but water source, too. Location comes into play for a lot of the advice from here, as the experts here refer to that sometimes, for all kinds of things. It's not just a personal profile element. Some of these guys are so good they can tell you the pH, TA, and CH of your fill water, based on what you put down for your Location! And they can advise what to do, or not, based on what they know about your evaporation replacement water. It's uncanny...

 

[Hanstb]

Dirk,

You where good enough to make that suggestion on a separate thread, and I am taking your advice, I was never that concerned with the exact volume of the pool until I found TFP and pool math, now I want to know precisely how much water we're working with. I purchased a good quality inline flow meter with a reported accuracy of 1%, the plan is to glue up a PVC manifold allowing multiple hoses to fill the pool simultaneously through the flow meter. As the water level rises in the pool, I will test the CH and adjust the flow of the hoses to achieve the target balance.

Unfortunately I am unable to blend the makeup water used by the Level Smart, only softened water is plumbed to the equipment room, I will have to periodically check the CH and adjust it manually. The only system that uses raw well water on the property is irrigation, so I will have to run a couple temporary hoses to fill the pool.

Replacing the sections of stained plumbing will require a little labor, but it's easy enough to accomplish, fortunately all the equipment and valves have union joints, this is the best idea I could come up with to quantify if the problem was in fact the Nature 2, or we have something else going on. For now I will forgo the time and expense of sending a sample to the lab, as I do not believe it poses any hazard.

I spoke to tech support at Hanna Instruments this morning to better understand the properties of the iron test I am using, and whether or not the test would react with silver, I was told it would not. So the test I performed on the sediment itself (described in post #4 of this thread) would not quantify, nor disprove, the presence of silver. The Hanna test does suffer interference from other metals, but it would be impossible to know which without further testing, testing that is beyond my capabilities. Incidentally the tech who took my call at Hanna was very helpful and spent quite a bit of time discussing this issue with me, great customer service!

Thank you once again to all who replied, if I come to have more information on this issue, I will update this thread.

Best regards

 

[Dirk]

Love the manifold/meter idea! Perfect solution.