black spots on bottom of attached spa...delamination?

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crackers8199

Bronze Supporter
Jun 5, 2014
319
Lake Elsinore, CA
so, i was just out doing my weekly maintenance, and as i was vacuuming the spa with my little hose vac i noticed there were black spots on the floor that aren't coming off. got out my bigger brush, thinking it was just some crud from the recent wind storms we've had that was stuck on...nope, still won't come off.

after draining my spa into the pool and taking a closer look, it seems this may be delamination...the spots are very smooth and a distinctively different texture from the plaster. where do i go from here on getting this fixed? am i looking at a full replaster?

you can see the spots just below the hose that is attached to the vac...
 

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Check them with some vitamin C tablets. Any change some iron fragments fell in the spa?
 
mknauss said:
Did you fertilize your lawn recently?
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nope. we have fake grass out back so no fertilizer out there ever...

i sent the pictures to one of the guys we have coming to do an estimate on cleaning and repainting our faux rocks, and he said it could be de-lamination but from what i know about that it doesn't seem likely that's the issue either.

i'll check it with vitamin C if i'm feeling frisky later, but it gets really cold as soon as the sun goes down. i was freezing when i got out just now already and it's almost dark now...might have to wait until tomorrow. unless i can use a grabby bar thingie to get the C to the bottom...
 
crackers8199 said:
i'll check it with vitamin C if i'm feeling frisky later, but it gets really cold as soon as the sun goes down. i was freezing when i got out just now already and it's almost dark now...might have to wait until tomorrow. unless i can use a grabby bar thingie to get the C to the bottom...
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Try crushing up the vitamin C in a sock or a knee high and using your pole to put it there if you dont want to heat your spa again.
 
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I would crush up 5 or 6 as best you can (or buy the powdered Vitamin C). No need to rub it, as you are really just trying to get the vitamin's acid in the water around the spot to see if it will remove it. I would let the sock sit there for 10-15 mins and see if it did anything.

Update - Here is the article in Pool School that references the process:
www.troublefreepool.com

Stains in Your Pool

The stained pool is beyond embarrassing. Our in-depth Guide to remove stains in your pool will help you to remove the stains and prevent them in the future.
www.troublefreepool.com www.troublefreepool.com
 
It looks like you're getting some copper stains.

The black might be copper stains that got further oxidized from turquoise to black.

Get about 10 vitamin C tabs and just drop them in the area and wait about 30 minutes to see if anything happens.
 

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we do have some crumbling concrete around the skimmer that is rusting a bit that is on the list to be fixed in the next few weeks (we have two bids and a third coming to give us a quote tomorrow), as soon as we get that third quote we will be making a decision and getting the work scheduled...could that be causing this? the odd thing that made me not even consider that (although of course i could be wrong) is that this was in the spa and the skimmer obviously is in the main pool...
 
tried crushing up about 8 C tablets and put them in a skimmer sock, and tried my best to put my two poles in the water to keep it down on the spot. after 15 minutes, they did absolutely nothing...however it's literally almost impossible to keep the sock down.
 
mguzzy said:
put a Rock or a paver on top.. Make sure whatever you weight down with is not going to create a further stain.. just sayin'.. if it was black algae you would see it come up with a wire brush.. or at least lighten in color as you break up the membrane.
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definitely not black algae then. i scrubbed with a stainless steel brush for about 5 minutes and it did absolutely nothing.

that being said, the vitamin C isn't doing anything.
 
I know where @JamesW is going with that.. if your Cartridges are picking up residual whatever stuff you will see it there... Also, I took another look at your pic.. would you say the dark specs are following the same speckle pattern of the lighter specs in your plaster? What kind of plaster did you have put in? I'm curious if you are seeing something in the plaster mix that is discoloring.. what it would be after 6 years I have no idea.. but I thought I would ask. I just following a preposterous theory to its illogical conclusion.
 
mguzzy said:
I know where @JamesW is going with that.. if your Cartridges are picking up residual whatever stuff you will see it there... Also, I took another look at your pic.. would you say the dark specs are following the same speckle pattern of the lighter specs in your plaster? What kind of plaster did you have put in? I'm curious if you are seeing something in the plaster mix that is discoloring.. what it would be after 6 years I have no idea.. but I thought I would ask. I just following a preposterous theory to its illogical conclusion.
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that's a good question...i wouldn't say they are following the same pattern but it looks kinda plausible that they are, if that makes sense? i hadn't even thought of that, i just assumed those little specs were just scaling that had built up over the years since the water is very hard (CH as of last test on saturday was 975).

we have never even had the pool acid washed in the just over six years since it was built, that's something i was considering getting done at the same time we have our rocks re-done over the next few weeks / months...was hoping to have everything done before we really get into summer (preferably before memorial day). rock cleaning / repainting, skimmer concrete fixed, and possibly an acid wash.

as for what kind of plaster, our paperwork says this:

"Two coats of white marbleized plaster hand troweled to a smooth finish. Plaster crew to install all directional eyeballs and drain covers on plaster day."

it's gray plaster, though. i do know that. that's on a separate sheet of options from the builder... "gray plaster" is broken out individually.
 
mguzzy said:
Ya know, you might be able to set your valves to drain the water from your spa into the pool.. I do it all the time to clean things and perform whatever maintenance... that would allow you to get closer to the stain and even see it with no water depending on your configuration.
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yeah i know i can do that (i've done it by accident a few times when switching back and forth between pool/spa since we have to do everything manually, never drained it completely though i always caught it before that happened). i always hesitate to do it intentionally for fear of overflowing the pool and wasting the water, or having the shell pop out of the ground (however unlikely, if that's going to happen it'll find a way to happen to me).
 

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