Need help to end the metal stain cycle

[shack42]

Hello folks -- We moved to a new home with an older in ground fiberglass pool (~6500 gal) last summer. The water was great and I hired a pool pro to take care of it and we swam happily for two months. Around late August, we noticed staining on the steps and a brown ring around the water edge. Pool guy did something and a few days later the pool turned bright green, then a funky brownish-green. Then pool guy turned it blue again. A few days later, the cycle repeated itself... again and again and again. We parted ways and then Pool guy 2 has been fighting the same fight ever since: brown->blue->green->brown. After four months, with no evident end to the madness in sight, I decided to take matters into my own hands.

Two days ago, I treated my stained pool with some ascorbic acid (Stain Free) and the stains lifted in about 30 minutes. I tried the polyfiber batting tricks to catch/filter out some of the metals, but that didn't seem to be very effective. I know the chlorine drops from adding the ascorbic acid, but i also know if I add more chlorine now, I'll be right back at the top of my cycle again.

I bought a K-2006 test kit and here are my levels today:

FC: 0
TC: 0.2
pH: 7.0-7.2
TA: 50
CH: 170
CYA: 62-63

I have a Hayward 5530 cartridge filter and a SmartPure Sanitizer chlorinator. Brand new cartridge filters were installed 30 days ago and the salt cell inspected/cleaned as well. I fill with municipal water and i purchased a pre-filter a few months back just in case the city water was the source; it made no difference. At one point, we drained about 18" from the pool, but I live at the coast and the high water table makes a full drain a sketchy idea for fear of the fiberglass shell popping out.

I really don't know if my goal is to eliminate the metals through some pool chemistry kungfu or always keep it in solution so it just doesn't settle out again.

Thanks in advance,
Chris

[Denniswiseman]

Your numbers don't seem to bad for a fibreglass pool except that you need to get chlorine up slowly with liquid chlorine and add a sequestrant to hold the iron in suspension
I have exactly the same problem and my pool popped out as well
I would be interested in chemistry kungfu but don't think there is

[shack42]

Thank you, Dennis.

As I'm a true amateur at this, can you tell me what you mean by get chlorine up slowly in terms of quantity over time -- XX mL per hour/day?

is there a recommended sequestrant i should use? My bottle of Metal Out says add a cap full once a week -- is this the advisable dose for my pool and problem?

Here's an image of my pool right now. The color is a little greenish, but it's reasonably clear:

My clorinator has these manufacturer recommended levels printed on it:
Chlorine 1 - 3 ppm
pH 7.2 - 7.6
Total Alkalinity 80 - 120 ppm
Stabilizer 60 - 80 ppm
Calcium 200 - 400 ppm
Salt 2700 -3400 ppm

The chlorinator has actually been switched off for about two months since it was generating chlorine and speeding up the stain cycle. I know I am low on salt right now and the reported level is 2500 on the display.

I've read that a lower pH will help keep the metal in solution. Should try to maintain about 7.2 pH level moving forward?

thanks again.

[Denniswiseman]

Thank you, Dennis.

As I'm a true amateur at this, can you tell me what you mean by get chlorine up slowly in terms of quantity over time -- XX mL per hour/day?

is there a recommended sequestrant i should use? My bottle of Metal Out says add a cap full once a week -- is this the advisable dose for my pool and problem?

Here's an image of my pool right now. The color is a little greenish, but it's reasonably clear:

My clorinator has these manufacturer recommended levels printed on it:
Chlorine 1 - 3 ppm
pH 7.2 - 7.6
Total Alkalinity 80 - 120 ppm
Stabilizer 60 - 80 ppm
Calcium 200 - 400 ppm
Salt 2700 -3400 ppm

The chlorinator has actually been switched off for about two months since it was generating chlorine and speeding up the stain cycle. I know I am low on salt right now and the reported level is 2500 on the display.

I've read that a lower pH will help keep the metal in solution. Should try to maintain about 7.2 pH level moving forward?

thanks again.

Forget about the manufacturers recommended levels as they are for general plaster pools
The stabiliser level is correct but you need a FC of 5-6 as the chlorine level is dependant on your CYA (stabilisor)
You needn't worry about calcium with a liner or fibreglass pool
TA and pH are OK but keep on the low side
When raising chlorine don't add a shock amount just enough to keep it at 5-6
The amount of metal out is relevant to your pool capacity not just a capfull
Interesting reading
Pool School
Slam (Shock Level and Maintain)
Chlorine / CYA Chart
Recommended Pool Levels
Pool Maths

[shack42]

Hi Dennis,

I started adding liquid bleach "slowly" as you suggested. The pool calculator site said "10 oz of 8% should raise FC by 1.1". Yesterday, I added 10oz and four hours later, i added another 10oz. This morning, I tested the water and I'm still showing there's no chlorine ?!?

I'm using a 2005K test kit and put two dippers of R-0870 into a 25mL sample and it did not turn pink which indicates no chlorine. I moved on to the combined chlorine test and it took one drop of R-0871 to change the color from pink to colorless (1 drop * 0.2 = 0.2).

The pool water is an aquamarine color. here's a pic:


Either I'm not adding enough bleach or i'm doing the test wrong or something is consuming the chlorine as quickly as I can add it.

thoughts?

thanks,
Chris

[Denniswiseman]

The AA in the water will use up the chlorine very quickly
Keep adding and testing maybe every two hours
This worried me when I first did an AA treatment
Don't worry you will soon be proficient
You may want to read Ascorbic Acid Treatment

[shack42]

Good news -- i finally have a measurable amount of FC in the water. Not much, but it's there.

Bad news -- staining on the walls happened at the same time and so the cycle repeats :/



Here's my test results today:
FC 0.2
CC 0.6
pH 7.2
TA 50
CYA 50

[Denniswiseman]

Did you put the sequestrant in? If you put a maintenance dose in it may not be enough
Rub some chlorine granules in a sock to see if it's algae, then rub some AA in a sock to see what moves it as you have some CC

[shack42]

I haven't been adding sequestrant regularly throughout this process. I did add a couple of ounces this morning as well as another dose of bleach.

I'll do the sock test and test the levels in about an hour and report back.

Thanks again.

[shack42]

Sock with AA took the stain off the fiberglass wall instantly. FC is back down to 0 and CC is reading 0.6.

Feels like I'm right back to square one again.

[Denniswiseman]

I just do the AA treatment add the complete dose of sequestrant for your pool capacity (not a maintenance dose). Then bring your FC up slowly

[Phil.c]

If you want the metal out of the water completely, in other words, by not adding sequestrants for ever then read my thread on how to do it.

[shack42]

Hi Phil,

I did read your thread last week and I did go out and buy some polyfill batting and stuffed into into socks in my skimmer basket and left it there throughout my recent mitigation attempt. After the AA treatment, my brownish pool turned a pretty blue when all the stains were lifted off the walls/floor. However, at no time did the socks or batting appear to capture anything at all. I even had a second external pool pump with its own basket stuffed with batting as I recycled water through it from the pool. There was no evidence it trapped anything either and it ran for two days.

Did you add any other chemicals (besides AA) when you ran your process?

thanks for the feedback.
Chris

[Phil.c]

The polyfill didn't show any colour when I did it, the only brown I saw was at the bottom of a cloth bag that the wet/used polyfill was put in.
Sods law.... a few weeks ago my twenty year old liner split, but up until then I had no returning metal and that was in a period of about eight weeks, previously the stain returned in a very short period of time.

I added no other chemicals when I ran the process, I changed the polyfill between one to three days, but used it all as it does no harm in the skimmer, so it was filtering for a few weeks.

Phil

[shack42]

I'm waiting on a shipment of chemicals and I'll do another AA treatment tomorrow. I got a bag of "skimmer socks" online and i'll stuff that full of the polyfill as well. I also ordered a cuLater Ultra 4.0 that I'll put in the filter basket. That culater might be $40 worth of pool snake oil, but at this point, I'm willing to try just about anything.