Black & Blue Stains on White Plaster

[Phizzy]

Hello kind members,

I have a white plaster pool that has developed black stains, mild blue stains, and a couple of yellow stains. After loads of reading, I'm thinking these are all metal stains and I'm planning on using the Jandy Stain Master to apply a modified no-drain acid wash to the entire pool surface (over time) while hoping the Culator catches free floating metals. However, I'm no expert and would appreciate any input as to what these stains are and if my acid wash idea could work.

Pool history: Pool was filled and started by a pool company 6 years ago. Since then, the only products I've used are liquid chlorine, liquid muriatic acid, and rare trichlor pucks for CYA. I have a pool heater and adjacent grass (fertilizer used 4 times per year). Plenty of leaves, pine needles, bird & small animal droppings make their way into the pool regularly.

What I've done so far (please also see photos):
1. Smudge test: Attempts to scrape the black stains have failed. But my SS pool light does sometimes get a smoky black residue. When I smudge a sample on white paper, it remains black.
2. Brushing: One week of 2/day SS brushing has only appeared to make a minimal impact on the black stains. Very hard pumice stone brushing gets rid of stain and exposes new white plaster.
3. Vitamin C: No change from Vitamin C application other than some Vitamin C tablet color staining (Used Orange-yellow tablets).
3. Trichlor pucks: Leaving the pucks on the stains for 20 minutes does nothing. After about 2-3h the staining (black/blue/yellow) circumscribing the pucks is totally gone. In the photos, the white areas around the 2 black lines (arrows) were cleared by trichlor pucks.
4. 33% Muriatic Acid: Applying acid directly onto the plaster via a pvc pipe immediately washes away the stains (& some plaster I assume) to expose white plaster.

I'm looking forward to any help with this currently ugly pool plaster.

Current chemistry (pool store, matches mine):
FC 3
TC 3.5 (but I just removed a rat from the skimmer)
pH 7.0
TA 20 (been doing a lot of acid dosing for stain testing)
Calcium Hardness 1500
CYA 10
IRON 0.1ppm (nl 0-0.2)
COPPER 0.5ppm (nl 0-0.2)
PHOSPHATES 687ppb (nl 0-100)
Salt 6200

Usual chemistry during season:
FC 3 TC 3 pH 7.6 TA 80 Calcium Hardness 1500 CYA 70 Salt 3200

Photos as described above. The last photo is a picture of some minor orange stains I noticed on my vacuum bag container.








Thank you!

 

[ajw22]

Welcome to TFP.

You have a bad case of copper staining and a high copper level in your water.

You need to figure out where the copper came from, lift the stains with sulfamic acid, and then drain your pool and fill it with fresh water.

Read…

Copper in Pool Water - Further Reading

www.troublefreepool.com

 

[Phizzy]

Thank you. So it's copper.

I would think the copper source is either the Jandy heater or the trichlor pucks (no ingredients specified for the "other 1%"). I can stop using the pucks but are there instructions somewhere to check if my heater's copper has been the source?

For copper removal:
1. Can I do the sulfamic acid treatment followed immediately by the no-drain water exchange? My hesitancy about this method is it would leave behind sulfamic acid byproducts (if I don't do a standard drain and refill).
2. Alternatively, can I use the Jandy Stain Remover with Muriatic acid across the entire pool surface to force the copper into solution followed immediately by the no-drain water exchange?

 

[ajw22]

I would think the copper source is either the Jandy heater or the trichlor pucks (no ingredients specified for the "other 1%"). I can stop using the pucks but are there instructions somewhere to check if my heater's copper has been the source?

Where are your trichlor pucks placed?

What brand trichlor pucks do you use?

Have you used any mineral systems in the pool like the Nature2?

For copper removal:
1. Can I do the sulfamic acid treatment followed immediately by the no-drain water exchange? My hesitancy about this method is it would leave behind sulfamic acid byproducts (if I don't do a standard drain and refill).

A No Drain Water Exchange is useful when you want to dilute chemical levels like CYA or CH. Dilution will not undo the effects of copper in the water or sulfamic acid. Especially with your high copper level. You will likely be left with enough copper in the water to continue to give you problems. A full drain and refill is the way to go.

2. Alternatively, can I use the Jandy Stain Remover with Muriatic acid across the entire pool surface to force the copper into solution followed immediately by the no-drain water exchange?

Using the Jandy stain remover to apply muriatic acid will be a time consuming process and the muriatic acid will be hard on your plaster. You will still need to drain the water for the reasons described above.

 

[mknauss]

Unless you live in the Sacramento Delta area, there really is no need to do a water exchange, especially at this time of year. Just drain it once you get the copper back into solution.

 

[Phizzy]

Where are your trichlor pucks placed?

What brand trichlor pucks do you use?

Have you used any mineral systems in the pool like the Nature2?

1. Trichlor placed in a floater (1 puck per year for CYA purposes) not counting the testing I did above placing them on plaster.
2. Trichlor brand: Kem Tek 99 3" Trichlor (link)
3. No. The only products I've used are liquid chlorine, liquid muriatic acid, and rare trichlor pucks. I don't know what the pool company used when the pool was drained and refilled 6 years ago.

I think I must have had low pH with the Jandy heater on at some point. Maybe I'll try to disassemble the heater and see if I can access the copper coils.

Looks like I'll have to do the sulfamic acid followed by a drain with a submersible pump (like this one). How do I know when I've got all the copper in solution? When the plaster is visually white as can be?

Thank you Allen & Marty.

 

[ajw22]

How do I know when I've got all the copper in solution? When the plaster is visually white as can be?

Yup.

One puck per year would not have caused this level of copper in your water. And the Kem-Tek trichlor does not contain copper anyway. Clorox trichlor and other chemicals that say "Blue" on the label are the problems.

 

[Phizzy]

I just visited the Jacks Magic #2 Copper and Scale Stuff website. I assume this (expensive) item is needed and not "sulfamic acid crystals" available at Home Depot? Might give dosing problems I suppose.

The instructions seem to be for using the filter to remove copper. Since I'm planning to drain, can I simply add 20 lbs. of Jacks Magic #2 Copper and Scale Stuff for a 20k pool, wait for it to work, then drain? Without using other chemicals?

Also, I'm assuming my Jandy JXi gas heater is bypassed when not turned on. But is there a way to confirm this? Seems like the bypass valve, if there is one, is internal. I wouldn't think sulfamic acid going to the copper coil would do me any good.

 

[ajw22]

I just visited the Jacks Magic #2 Copper and Scale Stuff website. I assume this (expensive) item is needed and not "sulfamic acid crystals" available at Home Depot? Might give dosing problems I suppose.

Jacks Magic #2 Copper and Scale Stuff is the best to use.

The instructions seem to be for using the filter to remove copper. Since I'm planning to drain, can I simply add 20 lbs. of Jacks Magic #2 Copper and Scale Stuff for a 20k pool, wait for it to work, then drain? Without using other chemicals?

Relying on your filter to remove the Cooper is hit or miss and will not get 100% of it.

I would plan on replacing your cartridge when fresh water is put in the pool.

Also, I'm assuming my Jandy JXi gas heater is bypassed when not turned on. But is there a way to confirm this? Seems like the bypass valve, if there is one, is internal. I wouldn't think sulfamic acid going to the copper coil would do me any good.

No it is not unless you have the Versaflo added to it.

You need to install a Heater Bypass - Further Reading to protect your heater.

 

[Phizzy]

Thank you again. So here seems to be the plan. 1) Install heater bypass plumbing, 2) Apply sulfamic acid (Jacks Magic #2 Copper and Scale Stuff) and run motor 24/7 until stains lift, 3) replace heater (with all that copper in the pool I can't imagine the heater coil is ok), 4) drain pool with submersible utility pump, 4) refill. Can't say I'm looking forward to this.

 

[ajw22]

I would replace the heater after you refill.

I would run the heater until it begins leaking. It may have more life remaining then you think.