Pool Builder blaming TFP Recommended Alkalinity levels for my staining

[NYAVGUY]

Hi,

I have been following TFP process since 2014 (when I joined) with the only exception being that I do phosphate treatments to lower my phosphates.

I am having some staining issues with my Skimmer and Vinyl liner and my Pool Builder says it is because I am keeping my Total Alkalinity too low and it should be 80-120 as recommended by pool manufacturers (I have a Latham Liner).

Below are my latest readings and photos of my skimmers (I have steel walls behind liner (assumedly galvanized). I winterize my pool and usually only have to adjust Alkalinity at the beginning of the season when it is low due to rain/snow coming through my safety cover. The gaskets around the supply's turn my fingers black when I touch them (also due to low Alkalinity according to my PB).

My Liner is 8-years old and in the past two years has started showing noticeable fading as can be seen on the bottom of the photo. Open to feedback/suggestions from the experts here. One item of note is that I did not install any type of anode with my SWG and I have an old Hayward Heater.


Build Type: Vinyl
Volume: 16500 gallons
Chemistry: SWG
------------------------------------------
Latest Test Result Summary:
FC: 6.5 (22 hours ago)
CC: 0.5 (22 hours ago)
pH: 7.8 (22 hours ago)
TA: 70 (22 hours ago)
CH: 250 (1 day ago)
CYA: 50 (1 day ago)
SALT: 3600 (1 day ago)
TEMPERATURE: 65° (1 day ago)
CSI: -0.33 (22 hours ago)
==========================================

 

[SJPoe]

The orange looks more like an Iron stain - if you rub a Vitamin C tablet on it, does it come off ?

I run with about 80 TA, and I get a little of the same around the skimmer, and I see the same 'black' if I rub the seals on the returns - I figured it was just normal rubber/neoprene+Chlorine degradation.
My Liner is of a similar age, and I'm starting to see some fading - but mostly in high-traffic areas, and I have no idea on the quality/make of the liner as it predates our purchase of the house.

 

[NYAVGUY]

Yes - it does come off with a vitamin C tablet, but this one is worse than the other. Here is a photo of the other one after I worked on it for an hour with a whole bottle of tablets.

I think at the beginning of next season I will do proper stain treatment which requires a very low chlorine level.

 

[SJPoe]

We need the chemists to chime in - but I doubt raising your TA by 10ppm is really going to make a big difference...

 

[JoyfulNoise]

Your pool builder is typical of the industry - they use bogus “water chemistry” arguments to avoid taking any responsibility for anything. It’s the nature of the business. There is no chemical rationale for why having low TA would matter in a vinyl pool. It’s an idiotic argument designed to act as a cover against any complaints.

That said, those stains are from iron which is pretty typically found in east coast water supplies. You need to do an ascorbic acid treatment to lift the stains and then either use a sequestering agent to hold the iron in solution or drain some of the pool and add fresh water that doesn’t have iron in it. Allowing rain water and snow melt to fill a pool is a great way to get fresh water in.

As for the fading - it’s an 8 year old vinyl liner in a chlorinated swimming pool … the pattern and color are going to fade. There’s nothing you can do about that. Fading and bleaching is usually worse on the walls of the pool that get the most sun exposure. Some liner colors and patterns do better than others in terms of fading but they will all fade eventually. A good liner lifetime is measured in how long it lasts before there’s a tear or a leak, not if the pattern or color holds. If you get 10-12 years out of liner without troubles, that’s as good as you can expect. Anything more than that is gravy.