Ascorbic acid BEFORE replacing water?

[skoch]

Hey.... I just replaced 2/3 of my pool water (23K gal in Dallas, TX) and successfully reduced CA from 538 to 265 (source has 110) and CYA from 115 to 45.

I've been noticing over the past 6 months (pool keeper quit and I've been learning ever since.... I suspect that he had been using a sequestrant) that the gunite surface is staining (started on steps and now is noticeable on walls and floor). When I started draining the pool I finally tested the stains with Vitamin C tablets and, sure enough, the stains disappeared instantly and completely. However, without thinking I continued to replace the water and now I'm realizing I should have lifted the metal off the pool surface with an ascorbic acid treatment BEFORE I removed 2/3 of the pool water.

So here's my question.... Did I get rid of most of the metal (i.e. still suspended in the removed water) or was most of the metal retained (i.e. still stuck to the walls)?

I kept a sample of the old water so.... I'll test the metal content in 1) the original water, 2) the new water, and 3) the water after doing an ascorbic acid treatment.

I'm hoping that test 1 is high, test 2 is low (i.e. the source water is low), and test 3 is also low (i.e. I didn't retain most of the metals by not removing them from the walls before replacing the water).

I will post the results ASAP. In the meantime.... what do you experts think I'll discover??? Also.... what's the best way to test for metal content (i.e. should I trust the pool stores or is there a more reliable place to test)???

 

[Swampwoman]

That kind of depends where the metal is/was coming from. If it's from your fill water, wouldn't have made much of a difference. Are you on a well?
If it's from former pool guy's copper products, maybe it will be better. If it's from fertilizer blowing into the pool it may be better until "next time" that happens.

Just a warning about testing. First off, staining is caused when metal oxides out of the water and onto a surface...sometimes from shocking, sometimes from incidents of higher ph.

Once the metal has precipitated into a stain, often as not, the water won't READ for metals. I've also found it doesn't read when there's sequestrate. But as the sequestrate erodes from not adding weekly maintenance dose, then the metal precipitates. So often, it's the stains that tell the story, not the water.

Pool store tester isn't any better -- they're the one's at first who told me I had no metals. Went home and tested my fill water and there was .5 ppm iron.

So, if you keep your ph in check (7.2 ish if possible) and play it by ear, there's a chance you'll be fine subsequent to water change. The stains will tell ya. Do test your fill water for iron. If you have .3 ppm or higher, you'll likely want to pre filter water when you add and maintain seqestrant, OR do a complete water change and truck the water in.

Constant sequestrate and AA treatments in my opinion kind of defeat the "trouble-freeness" of an otherwise BBB pool, so the water change might be worth it if you have well water. That's probably what I should have done when we bought this house last year but we were really concerned about unknown hydrogeologic issues at the time.

I also now have an outdoor faucet that's connected to our softener (but will only ever get 1450 gallons at a go without regenerating) so at least my fill water is now iron free

 

[Swampwoman]

PS I recently found AA on eBay for a decent price, btw - got 11 pounds of it for less than the price of two jars of stain away.

Second pps - AA seems to be most effective on iron, less so on copper. Copper seems to change Its composition, so at some levels/age of stain, it can look a bit like iron. If you want to be sure of what you're dealing with and don't mind buying stock in jack's magic they do sell a stain test kit that I probably should have used. They have different products for different stain types, and although they won't tell you exactly what's in them, I believe some of the treatments have oxaLic acid.

So, in terms of results, my AA treatment did clean up more recent staining, and lightened some historic stains of unknown origin (house was a foreclosure) -- but my water was cold (60) which I believe slows down the
process, and it was not te complete remediation id expected. Many people report more complete results. Just wanted you to know to expect the unexpected, and to be prepared to let it work longer if needed or to pre-test
to confirm what type(s) of stain you actually have.

In my case, it looks decent enough overall - I may wait until spring to see if I go further into my "stain study" as I'm starting to feel like Lady MacBeth

 

[skoch]

Thanks Swampwoman.... it sounds like I kept all the 'old' metal in my pool (i.e. attached to the walls)...

Once the metal has precipitated into a stain, often as not, the water won't READ for metals. I've also found it doesn't read when there's sequestrate. But as the sequestrate erodes from not adding weekly maintenance dose, then the metal precipitates. So often, it's the stains that tell the story, not the water.

A little more history....

• 1. Fill water is from tap (i.e. north Dallas).
  2. The pool is IG gunite with white surface.
  3. Since I inherited the pool roughly 6 months ago (maybe it's 9 months by now... was winter at the time) I have NOT added sequestrant.
  4. I've kept the FCL on the high side using Cal Hypo (4-10... but not as high as suggested given the high CYA... while adding to the very high CH) and have NOT needed to shock (pool not used much).
  5. The pool service before me was adding tablets so I continued (adding to the already high CYA).
  6. Slowly I let the PH go higher (not having any idea what the consequences might be) and at one point it got as high as 7.8. This is when the staining became obvious... especially on the stairs... and after doing some research I quickly lowered and have maintained the PH at 7.2 - 7.4... which seemed to stop the staining... maybe even reduce it a little.
  7. The staining is NOT severe... it's noticeable on the stairs (brown yellowish) and rather slight and barely noticeable across the whole pool surface.
  8. The two pool stores in the area were absolutely no help in learning how to take care of my pool (e.g. when I mentioned that the pool was starting to look stained they both said I should start adding sequestrant.... $50 to start and $25/mo.... and that if I'm lucky the stains will slowly fade.... said nothing about AA or getting the PH lower.... and this is in North Dallas with thousands of pools in all directions). On a scale of 1-10, with 10 being the amount to be learned by reading TFP, the two stores combined taught me maybe 1. I'm not exaggerating.... they clearly have no intention of educating their customers.... still, I'll bet that they'd have more business and higher profits if they were honest (i.e. the stores are generally empty with maybe a few others every time I go there).

So the main reason I'm posting.... no where did I see (and still can NOT find) someone clearly warning people (i.e. recommending) to "Do an AA Treatment BEFORE Replacing Pool Water" to make sure that metals are removed as much as possible.

Am I stuck with all the metals I had before? I'll have to keep PH low, add $25 of sequestrant every month, and worry that my pool will turn brown when I shock? Or simply live with the stained walls?

Shouldn't this concept be mentioned in the Pool School??? In a number of places it talks about "replacing water".... I wish it had said something like "BTW... if you have metals attached to your walls (i.e. stains), now (i.e. before replacing water) would be a good time to get the metals into the water with AA so that they are removed with the water".

 

[Swampwoman]

That's a valid point and maybe I, you, or we should attempt to write something up to that effect to contribute to pool school.

Based on your description of the staining, I suspect the AA treatment will be successful. I am unsure whether or not you will have improved your water quality in terms of metal with your drain -- if you have some of that water to test, let us know if you found trace metal or not! (If you did, then it will indeed be lowered...which is my hope for you!)

 

[skoch]

Thank you again Swampwoman.... particularly for saying that I might have a "valid point".... it helps me to build my confidence that I'm finally learning enough to properly take care of my pool (was absolutely new looking when I started and the slight staining has made it slightly dingy looking... which had me worried that I was damaging the pool).

Yes.... I did keep a bottle of the original water before replacing two thirds of it. I will not be able to do the AA Treatment until after next week.... but I will test the metal content of the before and after-replacement water and post the results by the end of this week (I'm so curious). And, of course, I will test again and post results after the AA Treatment (take water sample before adding sequestrant???).

Please, anyone.... should I trust the local pool stores to do the metal testing (i.e. I have very little confidence in them at this point)???
Yes, I agree with you Swampwoman.... we should lobby to get this "point" added to the Pool School if in fact it is "valid".... and hopefully others will chime in and either support or argue against it.

The general concept again....
If you're considering replacing your pool water (e.g. due to high CH or high CYA), look closely (and test) to see if there's any significant metal staining. If so, consider doing an AA Treatment just before removing the water so that a maximum amount of metal is removed from the pool with the water. Also, by removing the AA with the water, the process of bringing up the FCL in the remaining water will be that much easier and the reduced metal content (assuming the replacement water is lower in metals) will require less sequestrant. However, doing a AA Treatment with a water replacement will turn a one day project into a one to two week process.

 

[Swampwoman]

^Just so you know, sometimes the AA project can be a one to two week semi-closure project in the sense that if you hit it hard with Polyquat 60 (to avoid algae) AND lots of AA, AND you want to bring your chlorine up SLOWLY to avoid ph rises via over-chlorinating...well, it can take several days to get the water to "hold" chlorine so that you get up to swim-able levels. Just an advance word to the wise. YMMV