Anyone know what this is?

[shcuck]

Hi All,
Just recently I started noticing these rust colored areas at the bottom of the pool. As of now I would say I have around 8 or so. I have tried brushing them away but do not come off.

Anyone know what this might be and what I can do to get rid of them?

BTW, my pool is IG, 15,0000 Gal, Salt water, plaster.

My PH is at 7.8 (we have had a bit of rain lately, so just treated with Muriatic Acid to lower PH), CL is at about 5 ( just ran a full 100% chlorine session for about 13 hrs on the CL generator yesterday), HRD 350, CYA 20, ALK 80

Here is a pic.

Any guidance would be greatly appreciated.

 

[jblizzle]

Look like rust to me. You can try putting some crushed up vitamin C tablets on the stains ... if they lighten, that would confirm it is a metal stain.

Any chance some left a hair tie in the pool? I have 3 similar spots after one got left in my pool at some point.

BTW, your CYA is WAY too low for being in TX with a SWG ... if you raise it up, the SWG will have a much easier time maintaining adequate FC. You should never be needing to run at 100% like you did. If you need to boost the FC, then you should just use some bleach and it is faster and saves the life of the cell.

 

[linen]

BTW, your CYA is WAY too low for being in TX with a SWG

How did you test for cya? (your reporting hardness as HRD has me thinking that you are using test strips?)

 

[jblizzle]

BTW, your CYA is WAY too low for being in TX with a SWG

How did you test for cya? (your reporting hardness as HRD has me thinking that you are using test strips?)

Good catch ... my how often we have to read between the lines

 

[shcuck]

Thanks guys for the prompt replies. To answer you question about how I tested, I do use strips (insta strip, where you use your iphone to take a pic and it provides the read outs and it is amazingly accurate compared to the drop tests), but I also have the TF-100 test kit. When I want a quick reading of PH and CL, I use them, but for more in depth test I use the kit (about once per month).
Here are my readings from the TF-100 kit:
PH - 7.4
FC - 4
CC-0
TC - 4
CH-400
CYA - 10-20 (had to fill up the entire test tube (might be that my reaction solution is old))
TA - 70

Based on this, any thoughts? I too thought about some metal getting into the pool causing the rust, but don't think that is it, as there are more spots everyday, and the pool is clear of debris. A couple weeks ago, there was only the one spot on the pic and maybe 1 more, and today there are about 8 spots... All on the bottom and none on the walls.

 

[linen]

To answer you question about how I tested, I do use strips (insta strip, where you use your iphone to take a pic and it provides the read outs and it is amazingly accurate compared to the drop tests), but I also have the TF-100 test kit.

The tf-100 will be significantly more accurate than test strips as has been shown time and time again regardless of how the strip is being read. For sure the cya readings from strips are almost always way off.

CYA - 10-20 (had to fill up the entire test tube (might be that my reaction solution is old))

afaik, the cya solution has a long shelf life, especially if it has been stored where it doesn't get too hot or cold. Have you added any cya this year?

Based on this, any thoughts? I too thought about some metal getting into the pool causing the rust, but don't think that is it, as there are more spots everyday, and the pool is clear of debris. A couple weeks ago, there was only the one spot on the pic and maybe 1 more, and today there are about 8 spots... All on the bottom and none on the walls.

The one you showed sure looked like something metal sat there...we have heard of metal shavings getting into pools causing sporadic staining on the bottom? Is there any signs of roughness in the surface at the stains suggesting something coming out of the plaster?

 

[shcuck]

I have not added any CYA this year this far.

there is no sign or feel of anything coming up below the plaster, but I will take a few more pics of the other spots.. maybe that will help with with the diagnosis.

 

[shcuck]

Here are a few more pics of other spots... Sorry not the best quality pics, but was hard to take with the wind

 

[jblizzle]

still look like rust spots to me ... the way they kind of fan out due to water flow.

 

[shcuck]

Thanks a lot, I will try the Vitamin C to see how that works.

 

[Kochie]

Crazy as this may seem, one of my clients has the same staining in his pool floor and he assures me they result from duck droppings since he annually gets ducks breeding in his pool. I thought they were rust, but no rust treatments worked. I still have not been able to remove them but we are about to repaint the pool anyway.

 

[cbink]

Crazy as this may seem, one of my clients has the same staining in his pool floor and he assures me they result from duck droppings since he annually gets ducks breeding in his pool. I thought they were rust, but no rust treatments worked. I still have not been able to remove them but we are about to repaint the pool anyway.

Funnily enough, I have had a few 'rust' stains appear in the last week right by my spa spillover where birds have been pooing for the past couple of weeks. I'm still not positive what it is (it looks a bit like rust) but it's proximity to the spa spillover has me wondering if it was also droppings that got into the pool and sat there. That being said, if that were the case, I would have expected have been able to brush them off relatively easily, which I cannot...

 

[zea3]

I'm throwing a theory out there to go along with the presence of ducks/birds. It may be possible that the birds are rooting through soil that has been treated with a fertilizer containing iron, and ingest some of it while snacking on bugs and grubs. The iron then is excreted in the bird's waste that they have kindly deposited in your pool.