First SLAM

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Thanks KimKats

James, I am not sure how to answer your question
I inherited the pool in May when I bought the house.

What plaster do you have? - don't know

What is the original color of the plaster? - I'd say sky blue, maybe turquoise

Have you used any copper algaecide? - I never did but not sure what previous owner did. I remember some used algaecide in the shed that I threw away and never used (or maybe it was phosphate remover, I really can't remember, all I know is I never used it) Can't remember if it was copper based. My pool shop test on copper was 0.

Never had any troubles maintaining the pool TFP way.
Troubles started a few weeks ago after a massive storms, lots of debris in pool, and a FC level just at minimum for CYA.
 
The turquoise makes me think that you might have some copper staining unless the original color was turquoise.

The stains might be organic or scale. I don't think that it's algae because algae brushes off.

Maybe a bacteria or fungus.

What's the calcium hardness?

Try vitamin C on a spot to see if it does anything.
 
These are pre-SLAM numbers 6 days ago:

Results from poollogger.com

FC: 10
CC: 0
PH: 7.2
TA: 100
CH: 375
CYA: 70
Temp: 25
Salt: 4200
CSI: -0.48

In regards to brushing, I have used both metal and soft bristles brushes with no significant difference. Only using soft bristles now as I don't want to damage the plaster with the metal brush
 
My pH is quite stable between 7.6 and 7.8
I add MA when above 7.8, testing every 2 days when not SLAMing, so if pH has been over 7.9 it would have been for 24h max

I normal times, I only need to add MA every 3-4 weeks to bring pH down to 7.6
 
Seems like you're doing everything properly. Definitely a mystery what the stains are.

Try vitamin C to see if it does anything.

The chlorine tab test seems to indicate organics, but the lack results from SLAMMING seem to point away from organics.
 
I think the trigger is your water temp coming up for summer. I don't think it's anything you're doing or not doing. Though repeating the SLAM can't hurt.

I just got some black algae patches (12 of them) on my mate's pool which are now gone!, phew.

History: I did a no-reason spring SLAM, and I haven't seen a reading less than 7.5% (I target 10% FC/CYA and it's SWC). The pool is brushed weekly by robot, and I do the steps, waterline, ledge and a couple spots where I never see the robot going. Black spots showed up out of the blue when the pool got to 25C (77F). No joy from nylon or steel brush alone with pool at mid-point between target and Shock. Tried a SLAM and no luck. OCLT has been 0 to 0.5 each time I've checked it, throughout this ordeal. None of the spots were on areas that I brush manually.

A puck over them solved it. 5 days and lots of steel brush. And I learned "do not leave a puck on more than 15 minutes" cause although the owner or a visitor will never notice them, there are 5 round 3" patches of plaster lighter than the plaster right beside them. Those got 30 minutes of continuous puck, my bad.

My procedure was 2 or 3 times a day:
- Steel brush 10 passes
- Pucks over the spots for 10-15 minutes
- Move puck to another spot, steel brush again, 10 scrubs
- Pucks back to original spot for another 5-10 minutes, then brush, etc. etc.
- Remove the pucks
- Turn on the robot and go home
- After 3 days, they were really faint. I had to go when it was cloudy, because with any ripple at all and I couldn't find the spots. Easier to find on the bleached circles I mentioned above.
- Pool was at SLAM (20 ppm FC; 50 ppm CYA throughout)

Spots are now gone, but I'm keeping the pool at 12 ppm FC for 50 ppm CYA for now.

This is sure not a diagnosis mate and I'm really glad JamesW is here. That man knows his stuff and is tenacious :) Hopefully my experience is a clue.
 
Thanks all.

Jet, I got my scuba gear out and I have been rubbing the pucks all over the stains then metal brushing, just because, as you mentioned, with ripples you can't see anything from above.

This seemed to make a difference.
Unfortunately I ran out of air in my tank and I haven't had a chance to get a refill, so doing it same but snorkel style, but I can't stay underwater rubbing and scrubbing for more than 20-30 seconds at a time so it's taking a lot of time.

Will try Vit C for a minute and will report back.

Thanks again

PS: no need to bring FC to mustard level, right?
 

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Hi Yan. Sorry you're not getting results but I have a hunch, as does James I think ;)

Re:
They are definitely organic, since the direct application of pucks make them go away, and they don't come back.
Click to expand...

Pucks are acidic and acid will sometimes liberate a metal stain. So the following min-tests might help demystify the stains.

1. If you have or can get a small bit of dry acid (eg little bottle of spa ph down), put the powder in a sock, put on a rubber glove to protect your hand, rub the spots a bit and see if they don't lighten. Could be copper, whch can blacken, or maganese, or some combo of metallic plus scale.

2. Crush up some vitamin c in a sock and also rub/apply. If the spot initially darkens, but later starts to lighten a bit, or just blackens, the culprit likely involves copper. Don't use Ascorbic acid to clean in this case; but you could use an acid-feeding wand to carefully clean the area with muriatic acid.

If, on the other hand, vitamin c completely lifts the area, its more likely maganese or discolored iron and should respond to either an AA treatment or spot treating with ascorbic acid loaded into a dishwasher wand with cap, mix AA with water 50/50.

Let us know if either of the experiments gve you anymore info to work with. If so, I can post a link to the type of underwater wand that works with MA.
 
Hey!

Thanks so much everyone for the input.

I just tried the Vit C powder but it's such a sunny day today, I can barely see the patches, let alone any kind of changes when applying Vit C.

I'll have to try later today or another day.

Should I consider SLAM over anyway? And let FC drift down to 8-9?
 
I suspect that the SLAM did what it could do. I think that it’s still not clear what you’re dealing with. It could be metal, organic or scale. At this point, I think that I would maintain good chemistry and brush a lot. Try the steps given by SwampWoman when you get a chance. Maybe add a sequestrant.

If you can get better pictures, that would help. Underwater pictures would be best.
 
I'll try to shot some GoPro later when the patches are more visible

Should I take a sample to the store for metal testing? I need to go there to get Spa pH down as SwampWoman suggested.

Thanks again for your help.
 
Metal testing can be helpful if it produces a reading.

However, often the result will be below the sensitivity of the test. If the metal has all formed stains, there might not be much left in the water.
 
Swampwoman said:
Hi Yan. Sorry you're not getting results but I have a hunch, as does James I think ;)

Re:

Pucks are acidic and acid will sometimes liberate a metal stain. So the following min-tests might help demystify the stains.

1. If you have or can get a small bit of dry acid (eg little bottle of spa ph down), put the powder in a sock, put on a rubber glove to protect your hand, rub the spots a bit and see if they don't lighten. Could be copper, whch can blacken, or maganese, or some combo of metallic plus scale.

2. Crush up some vitamin c in a sock and also rub/apply. If the spot initially darkens, but later starts to lighten a bit, or just blackens, the culprit likely involves copper. Don't use Ascorbic acid to clean in this case; but you could use an acid-feeding wand to carefully clean the area with muriatic acid.

If, on the other hand, vitamin c completely lifts the area, its more likely maganese or discolored iron and should respond to either an AA treatment or spot treating with ascorbic acid loaded into a dishwasher wand with cap, mix AA with water 50/50.

Let us know if either of the experiments gve you anymore info to work with. If so, I can post a link to the type of underwater wand that works with MA.
Click to expand...

Swampwoman

ive got 2 options for spa ph down. Which one is Best ?
920g/kg hydroxytricarballylic acid or
1000g/kg sodium bisulphate

thanks
 

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