Brown Stains only on PVC

[mmelkonian]

First post here, but I've looked over alot of the posts and can't find anything exactly like my problem so here goes

I have brown stains on the PVC skimmer housing/baskets (see attached image) , filter basket and inside fitting in the pool, to a lesser degree the pvc on the polaris fittings and the bottom of the polaris 360 (the white part) Interestingly this does not seem to affect the spa fittings (spa overflowing into pool so 80% of return water goes to spa first)

The pool is now 2 seasons old, I originally did add some algae agent (as I was instructed) but never really kept up with that, Also have the Nature 2 installed but only changed the cartridge twice since having the pool and I just removed it barely had any material left in it. I do have a heater. temp kept at 84

Have not gotten any formal tests for copper or iron but did take one of the fittings off and put it in a cup and crushed up some Vit C tabs and it nicely removed the stain, the next eyeball fitting I tried didn't come clean but being resourceful I looked around the house and found some Bar Keepers Friend mixed up in a cup and presto the stains came off (looking at the label it says it contains oxalic acid) as well, removing the skimmer baskets it was easy to clean the brown stains with this agent so I'm reasonably convinced from what I'm reading here it's likely iron staining.

My issue is this only seems to be affecting the PVC and not the pool walls which are pristine (it's Caribbean pebbletec so granted it might be hard to judge if there was a light layer covering everywhere but certainly no blotches anywhere . Never had algae, water has always been clear, live in NC and we use the spa in winter so I never shut the pool down just reduce filter times in winter

Now the questions
1. So should I just clean these areas locally or would an AA or oxalic acid treatment be warranted for the whole pool?
2. should I routinely be adding a sequestrate to prevent them from coming back?
3. Now that I'm not planning on using the Nature2 is there something I need to add to prevent any copper that was introduced by this system from causing problems?
4. Can I use something like Jacks Ionizer stuff instead of AA

For interest sake can anyone explain why I don't get these stains at all on the spa fittings

the circuit is pump-> filter-> Nature2 -> Heater -> split returns to spa and pool with the pool also having the Venturi and inline chlorinator

if it was the Nature2 I would expect it to affect both areas
Only the chlorinator and the ozone only go to the pool, but if it was the ozone why is it affecting the return baskets since the ozone should be well gone by then?


(FYI in past had been using trichlor until I found this site , CYA was off charts after half drain and refill it's 70, now using Cal-hypo until my CH gets up and then will use bleach, with trichlor in the chlorinator for vacation times
FC 5.5 (in the PM) targeting 8
CC 0
TA 100
CYA 70
CH 230
Using 2000K kit

 

[Insomnix]

Ok. there are a few things that could be going on here. First, if you have a lot of leaves, the skimmers in the pool will collect these an the metals in the leaves and cause this type of staining, explaining why the spa does not seem to see it. Next, if 80% of the water goes to the spa, than that leaves 20% to circulate the pool, this would lead to more standing areas in the pool and less flow. The stains, if not from leaves, look like iron stains to me. Oxalic Acid (AKA Pool Stain Treat) is a good resource to remove these stains. Vitamin C is ascorbic acid and not as efficiet. You could get some Oxalic and put it in an old sock or something similar, turn off the pool and set it by the skimmer where the stains are the worse. Let it sit about 30 minutes then check it. Nature 2 contains copper. But I would use a metal chelating agent once these stains are removed. I would , however alter it as well to send maybe 20% to the spa, or even as much as 40%, but the pool really needs good circulation on the returns.

 

[JasonLion]

Are those stains oily and smear around, or are they completely fixed? Oily stains are a whole different thing.

Before trying anything with oxalic acid, hold a vitamin C tablet against one of the stained areas and see if the stain lightens or goes away. If the vitamin C tablet helps then treat the entire area with ascorbic acid or vitamin C. I prefer ascorbic acid, since oxalic acid is more annoying/dangerous to handle.

 

[mmelkonian]

Should have maybe included a pic of the pool but the pumps are pulling water from the pool and dumping in the spa which then waterfalls into pool so when in pool mode all the water is circulating.

Vitamin C tab (and I assume people are talking about ones you can take when you have a cold) did remove similar stains from the eyeball fittings

The stains do not smear although with some scrubbing with a scrubby pad you can get some of it off, but soaking the skimmer baskets in a bucket with a little of the bar keeper friend stuff cleaned them without scrubbing I'm assuming it's the oxalic acid in the product the rest of the product seems to be a fine abrasive that fell to the bottom of the bucket

Maybe I will try a trichlor puck overnight when the pump is off to be sure

 

[Insomnix]

I will point out the corrosive aspects of a tablet, also, if this is metal, it could react. But, I did fail to mention the oily side of it, sorry.

 

[mmelkonian]

well here's a follow up

on another persons post they mentioned a product Iron Out found at Lowes

Now I would never add this stuff directly to the pool but what I did was....

walled off the skimmers with a tight fitting piece of wood
shut the valves to the skimmers so they were isolated
poured only a tablespoon of the iron out in and gave it a swirl
within 30 sec all the stains were gone

I then removed the water by scooping it out which I think will serve two purposes, one to prevent this chemical from getting into the pool at large, and two removing the iron that was now suspended in the solution to get it out of my water.

I'm thinking I will wait to see if the stains recur before regularly using a sequestrate since it's only seems to accumulate on the skimmer/baskets this might be a way to remove the iron from the water similar to the CuLator material but without the cost

(that's a temporary fix for a broken handle int he picture if anyone was wondering, drill two holes and loop some nylon thread)