Vitamin C - how to apply over a stain to check it ?

[cody21]

We have a few stains that I mentiuoned here some time back, and they're still there ... I was going to do the Vitamin C trick to see if it is organic (algae?) or metalic ...

How many tablets should I use? Do I crush them and put the mix in a sock? and how do I put the sock over the stain (on the bottom of pool)? How long do I leave it there?

Thanks

 

[cody21]

Never mind ... I found the info in POOL SCHOOL .... press/hold tablet on spot for 30 secs ... see if it goes away = METALIC stain, else likely Algae

 

[jblizzle]

Yeah, I think you can just rub it on if the spots are small. larger spots, just put a few broken up in a sock and set it on the stain for a while.

 

[cody21]

SO, I tried the test by applying a Vit C tab to 1 of many stains we have ... Yep, metal (iron?) ... Actually, I was quite amazed at just how WHITE the pool surface got so fast. The resdiual small "pit" must be a leaching of a small tiny hole from the underlying gunite. Is that correct? (as a side, why does that doe that?) And generally, as I look at the pool surface/fiberglass underwater with my goggles on, it has a generally-brownish tint .. this vitamin C test DEFINITELY whitened the surface area I applied it to ... So, next step would be a total AA treatment.

questions:

- Would you just wait until next Opening season to do the AA "process", or would you do it NOW before basically shutting down the pool for the year? We're getting close to end of season here in my area. Probably another 2-3 weeks t most with the nights getting into the high 40's. (Our area doesn't actually go to Freezing temps, but we'll just be maintaining proper levels throughout winter.)

- Several years have gone by since the original post on the AA treatment, and a lot of the comments are old. Do the procedures on page 1 still apply? or are there other products to be considered?

- There is discussion about adding a "sequestrant" - what is that???? Several people here asked and I never saw a reply. Is that the Absorbic Acid ?

thanks !

 

[chem geek]

The first post in the Pool School article Metals in the Water and Metal Sequestrants is still appropriate and describes the HEDP-based metal sequestrants that are recommended. These will keep the metal in the solution preventing further staining. These products break down so need to be added regularly (usually a little each week). Eventually, drain/refill of water over time should dilute the metal content of the water unless your fill water has metals in it.

 

[cody21]

Thank you ! I'll take a look at that.

 

[cody21]

OK, follow up question then ... If I was to get one of those sequestrants (e.g., Metal Magic), do they actually REMOVE existing stains? Or would I have to the tha AA treatment first, then start adding the Metal Magic sequestrant? Sorry if that's a stupid question ... I'm still learning. Thanks again.

 

[Swampwoman]

Do AA treatment first, then use sequestrate to prevent stain from REFORMING - it bonds the released iron into a water-soluable form, BUT stains can redeposit if you don't maintain sequestrate levels or if you have a high PH event.

 

[cody21]

Thanks again ...

 

[cody21]

Oh, and that other question I had -- would you do it at pool CLOSE DOWN time (the AA treatment), or would you wait until next summer when we OPEN the pool back up ??

 

[Swampwoman]

Cody, IF you can do it and be finished more than 2 WEEKS before you close, you can do it prior to closing.
The reason I say that is that you should not SHOCK for more than 2 weeks after an AA treatment, and you need to SHOCK to close (or at least bring up to shock levels day prior).
But it also takes "about a week" to fully "recover" from the AA treatment in that it may take that long to slowly bring your chlorine back up to normal levels and have it hold. So that's effectively 3 weeks between AA and close.

Lastly, whether you do it before closing or in spring before swimming weather, note that the AA can take considerably longer to WORK in colder water...

So the choice is yours, but aim for warmer water OR a longer treatment time, as the case may be. Colder water, however, is great for averting/avoiding algae when the chlorine is low, which is required for the AA treatment and process.

 

[cody21]

Great points and options .. Thank you.

 

[Debslemm]

Never mind ... I found the info in POOL SCHOOL .... press/hold tablet on spot for 30 secs ... see if it goes away = METALIC stain, else likely Algae

Works like magic! I have brown stains on steps every year when we open the pool. I dump vitamin c tablets on the steps, let them sit for a little, rub them over the surface with my hands or sock or sponge and wowza! Sparkling white steps! Doing this for 22 years!