Yellow tint on bottom of deep end

I have a 22k gallon gunite pool with a SWC. Within the last month, a yellow tint has appeared at the bottom of the deep end. It is only in the deep end (8 ft), and only on the bottom of the pool, not the walls. There is a pretty clear line where the tint stops when the bottom of the pool starts to rise to meet the wall. I shocked the pool and it had no effect. I tried the Vitamin C test and it had no effect (earlier in the year we had a metal stain problem and the ascorbic acid worked like a charm). I've tried brushing and that didn't do anything either. Any ideas? I don't have current chlor, ph, etc. since we just shocked yesterday, but the chlorine is typically around 3 and ph is 7.2 to 7.4.

Thanks in advance.

What's your CYA level?

We've just had 2 days of rain so this is the first chance I've had to get the readings:

FC = 1 (it isn't always this low. I had turned down the SWG when I shocked it and forgot to turn back up)
CC = 0
ph = 7.8 (prob higher b/c rain - I'll treat with acid tonight)
Cal = 220
CYA = 29
temp = 72 (down 8 degrees this week thanks to the rain and much, much cooler weather)

Any thoughts are appreciated.

What did you shock for? Did you try to rub a trichlor puck on the stain? You can also put some ph down in a sock and rub it on the stain. If the stain comes off with the ph down, then it is probably metals, if it comes off with chlorine then it is organic. You may not have had enough of the vitamin c to make a difference. Did the stains come before the the shock? You wouldn't get any metal stains from low chlorine and low ph, that is why I would guess that if the stains cam e before the shock, the stains would be organic. Let us know if either the ph down or the chlorine work.

The stains came before the shock. I shocked thinking it would take care of the stains since the small vitamin C test didn't have any affect. I'll try both the ph down-in-a-sock and trichlor tests, but I have a really dumb question about the puck. I have "stabilized chlorine sticks" (brand and item: Bioguard Stingy Sticks). The active ingredient is trichloro-s-triazinetrione. Is that the same as the trichlor puck you mention?

It looks like metal stains. I had some ascorbic acid from my metal stain issue earlier this summer, so I put some in a sock and sunk into the deep end. Within a couple of minutes, the area around the sock turned darker brown, and a clean white trail emerged in a line between the sock and the main drain below it. I assume the darker brown was the stains lifting off the bottom. The darker stain did significantly lessen after a few minutes, but I assume that could be the ascorbic acid in the pool. So... do you think I need the full ascorbic acid treatment or should I just try some metal stain remover?

How much ascorbic acid do you have? You may want to try the sequestering agent first, because you need to put it in anyway, even if you do the treatment. I would lower the ph down to 7 - 7.2 add the sequesterer - make sure you use enough - more is better than not enough. If after 24 hours you don't see the stain lighten, then use the ascorbic acid, you probably won't need as much as you used the first time. Just bring your chlorine level down, and pour the ascorbic acid where the stain is the most noticable. Let us know how it goes:)

Quote:

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Originally Posted by cmcq

I have "stabilized chlorine sticks" (brand and item: Bioguard Stingy Sticks). The active ingredient is trichloro-s-triazinetrione. Is that the same as the trichlor puck you mention?

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Yes, it's the same thing.

Janet

I added the sequestering agent two days ago, and I think it worked, but \I can't be 100% sureright now b/c the water is now very cloudy so I can't see the bottom of the pool from the pool deck. I haven't had time to dive down and look at the bottome of the deep end, but some stains that hat started appearing on the steps are gone. I checked the chlorine and is is 0, and the PH is 6.8. I've also now found mustard-colored spots on the steps and walls of the pool which brush off with no effort. I ***ume those are due to the lack of chlorine, which is due to having added some ascorbic acid when diagnosing the stain and the sequestering agent after that. Does that sound right? If so, the question is how quickly do I bring the chlorine back up to get the water re-balanced? Can I rely on the SWG or can/should I add some trichor sticks to the skimmmer? The final added complication is that we're scheduled to have the pool closed in 9 days, and I ***ume I need all this cleared up by then.

Thanks

You can start to bring the chlorine up now - bring it up slowly. If you have a sand or DE filter, put a trichlor stick in the skimmer, and keep it there until the water clears, this helps to let any stain that will for when it hits the chlorine to stain the filter instead of the pool. Keep adding chlorine to get the chlorine up to 6, while keeping the ph at 7.2, and no higher. If you don't see any stains forming, you can take it up to shock level, if you see stains make sure the ph is btween 7 & 7.2 and add more sequesterer. Then take it up to shock, which for you would be between 12 & 15ppms. You will have a hard time keeping the chlorine up because it is working to get rid of stuff in the water which is eating up the chlorine. You will have to be consistant. Keep the filter running 24/7. You can keep your SWG going, or you can shut it off while you are maintaining the chlorine so closely yourself.

As for clearing it up before the pool closes, I would just make sure that you have killed off any algae that you may have - which may be to use mega doses of chlorine. You shouldn't close until the chlorine is holding steady overnight and you have no combined chlorine. There seems to be a form of brown algae that is going around that needs mega doses of chlorine to kill it - here is a link to a thread about it.
http://www.poolforum.com/pf2/showthread.php?t=5612
I think killing the algae off is more important than the staining - I have already closed my pool with a lot of staining, and opened in the spring to no stains!!! I think if you have enough sequesterer in the water and keep your ph down, you should be able to get up to shock levels without getting more stains. Just keep the filter running 24/7, keep a trichlor stick in the skimmer, and when you add bleach DO NOT add it to the skimmer with the trichlor in it! Add it to the return stream. Good luck, and feel free to ask any questiions you may have:)