Ascorbic acid treatment for stains, which sequestering agent to use?

[MountainStone]

Doc,

I'm willing to attempt this following your direction and document the process. My two concerns are that I don't want the pool to be out of service for too long (we're anxious to get in our first pool and the weather is rapidly warming here in Vegas) and I do want to eventually eliminate all the stains in my shiny blue fiberglass pool. You say your guess is that I'll not be able to remove 100% of the stains with your process and I can live with that through this experiment, but I do want to find a way to remove them all before the end of the season. I recently received my K-2006 upon your recommendation, and am currently keeping my pH low and aerating to lower my TA. My calcium is at 600ppm and will rise due to high calcium in my fill water and high evaporation rate (dunno if that makes any difference). I'm willing to start whenever you are, again provided that the pool is not out of service for an extended period.

[PoolDoc]

Are y'all not swimming now? I just looked at your weather forecast, and it's showing lows in the 70's and highs in the 90's for the next week.

As far as 'out of service' -- I would only anticipate it being out of service for a couple of days while you were treating it with the ascorbic acid. None of the other things would be incompatible with swimming.

Let me contact Chem_Geek and Marie, and also, I need to get the chemical info page posted, so I can direct you to the exact products you need.

High evaporation + high calcium fill will absolutely tend to cause a climbing calcium level. I'm posting your test results from your earlier thread here, for reference in this thread:

Fill water:
FC = 1.2 ppm
CC = .2 ppm
pH = 7.6
TA = 140 ppm
CH = 270 ppm

Pool water:
FC = 4.2 ppm
CC = .2 ppm
pH = 7.8 (acid demand test yielded 1 drop to bring to 7.6)
TA = 180 ppm
CH = 600 ppm (tested this 4 times, once at 25ml and 3 times at 10ml)
CYA = 90 ppm

If you could, go ahead and take pictures of your pool, and your equipment, and send them to me (poolforum@gmail.com) for a reference post.

[MountainStone]

Doc,

We have yet to get in the pool though we are quite anxious to try it out. Water temp hit 70 yesterday for the first time and the forecast calls for highs in the 90s the next few days. The sunshine is a physical force here in the desert, so we may attempt a short dip at midday this weekend; the water's just been a little too cold up to this point.

I'm fine with no swimming for a couple days; glad that is no barrier. I mentioned the high calcium because I didn't know if it would factor into your prescription. My test results today are pH: 7.2 and TA: 120ppm. I am adding dry acid every day to keep pH low and aerating to bring down the TA. I currently use trichlor in a floater for sanitation.

I sent photos of my pool and equipment to the address you listed.

[chem geek]

As far as 'out of service' -- I would only anticipate it being out of service for a couple of days while you were treating it with the ascorbic acid. None of the other things would be incompatible with swimming.

Let me contact Chem_Geek and Marie, and also, I need to get the chemical info page posted, so I can direct you to the exact products you need.

You only need to stay out of the pool during the time the ascorbic acid is working to remove the metal stains. The reason is that ascrobic acid will remove all the chlorine in the pool so it will be unsanitary during that time. Usually the stains will get removed within a day or two, sometimes in a matter of hours (depends on how old the stains are). Ascorbic acid works better for iron stains; not as much for copper stains.

So you would let the chlorine drop somewhat on its own before adding the ascorbic acid so you don't waste so much money on having ascorbic acid just get rid of the chlorine (you wouldn't let the chlorine drop much below Ben's minimum FC chart, but you can let it certainly get to or slightly below that minimum). If your pH isn't somewhat on the lower side (definitely below 7.5) then lower it. Then add enough ascorbic acid to get rid of the FC and have extra left over. One pound of ascorbic acid in 10,000 gallons gets rid of 5 ppm FC. So any excess beyond the amount needed to get rid of the chlorine will be used to reduce the metal stains and get them into the pool water.

The ascorbic acid will also lower the pH more which is part of how it works (it's also a reducing agent). Once the stains are gone then you'll add a metal sequestrant that has HEDP such as Ben referred to. That will keep it in solution at least for some time -- it breaks down over weeks from chlorine, but fortunately not as quickly as EDTA-based metal sequestrants that break down in days to 1 week and create a much higher chlorine demand. After you've added the metal sequestrant and had it circulate for an hour or so, you slowly add chlorine and can also slowly raise the pH over time. You can swim as soon as you've got the minimum FC level from Ben's chart for your CYA level. If the pH is still on the low side, that's OK for swimming since it's not horribly low.

As for the CuLator®, you can add that packet anytime into your skimmer, but normally would add it after you've added the metal sequestrant. The CuLator isn't fast, but will remove (absorb) metals even when bound to metal sequestrant. It will take weeks of circulation to remove most of the metal and if there is a lot of it then it could take more than one bag though as Ben points out if there isn't very much then a bag could be used again at another time.

[MountainStone]

Thanks very much for joining this thread, Chem Geek! You make it sound pretty easy, which builds my confidence (new pool and still afraid I'll 'break' it). At this point I'm just waiting for Ben to give me his step-by-step instructions, bill of materials, and guidelines for documentation.

[PoolDoc]

Here are the photos:











1.5HP uprate motor


PRA6F-148L






Enhanced view of stain


StaRite PXC150 filter


Enhanced view of stain

[mbar]

I have a fiberglass pool, and live in the middle of the woods with a mesh cover - so when I open, my pool is dirty and there are always some leaves that find their way under the cover. First thing I do is vacuum to waste, add lots of bleach and let the filter run 24/7 till the water clears. Once clear there is usually staining (due to keeping the chlorine at shock levels for a few days). I don't bother balancing the water until I finish the stain treatment because after the treatment you have to rebalance anyway. Once the water is algae free and reasonably clear I wait about 2 days till the chlorine comes down to about 2, I put the filter on circulate, I add the ascorbic acid, enough to go around the pool on the sides (about 1 to 2 lbs.) and let it recirculate for about 1/2 hour, and make sure there are no more stains. When the stains are all lifted I add 2 bottles of sequestering agent. I let this recirculate for about an hour. I then put the pump on filter and add 1 puck to my skimmer basket. ( I know this is not recommended, but I do it so that there is some chlorine going in the pool, and I never had any problems with this) Then I keep the filter on 24/7 for a day and start to slowly add chlorine to my pool. The pool will not hold chlorine, so you have to keep adding it until all of the ascorbic acid is gone. Depending on how much you use will depend on how long it takes to hold chlorine. Since I don't have to worry about a liner, I don't worry so much about getting the ph up. I do it slowly, and watch for stains to return. If I am all clear I get the water balanced. Last year I did use the CuLator, and it seemed to work well for me. I am going to use it again this year and will let you know how it does. I may even do some experimenting to see what happens if I get my chlorine high with high ph. All I have learned about getting rid of stains has been by experimenting and seeing what works - it always helps to have everyones feedback, so we can learn from each other.

[Watermom]

Marie,
It is great to see you back on the forum! We have missed you and also your great advice for so many people who have stain problems in their pools!

Again, welcome back!

[PoolDoc]

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Amazon
Many of these chemicals will be available locally . . . but the problem is, you probably won't be able to tell. Pool chemical companies put a lot of effort into hiding what's actually in their products. I had to work pretty hard to make SURE that these chemicals were what we needed. I've tried to indicate the products that you may find -- and identify correctly -- locally. However, if you can find the Kem-Tek brand locally, and find IDENTICAL products, they should be the same locally as on Amazon.

1. Kem-Tek 60% polyquat => $18
0.7 ppm per fluid oz; 4 ppm dose = ~ 1 cup liquid measure.
Polyquat is available locally, but this is a pretty good price.

2. KemTek 20% HEDP "Metal & Calcium Eliminator " => $14 (but, get 2 bottles = $28)
0.2 ppm per fluid oz; 2 ppm dose = 1.5 cups fluid measure
It's very difficult to identify the concentration of HEDP products.

3. Photographers' Formulary Sodium Thiosulfate, 1lb => $7
1/3 lb should remove 5 ppm of chlorine from your pool.

4. Ascorbic acid => $17 (but, get 2 pounds = $34)

5. CuLator, 1.5 ppm => $40 (does NOT ship from Amazon)
CuLator, 5 ppm => $70 (does NOT ship from Amazon)
Your choice on which one to buy. If they work as advertised, the smaller one should be sufficient.

6. In the Swim 24 x 1# Cal Hypo => $64 ($2.67/lb) (does NOT ship from Amazon)

Optional:
7. Iron Out, 30 oz => $10, delivered. Does NOT ship from Amazon. Small bottles are probably available locally.


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Local:

8. (5) boxes of 20 Mule Team Borax => Walmart

9. (2) gallons of muriatic acid => Lowes, Home Depot, Ace Hardware

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Testkits

You will need either the K2006 (preferred) or the K1000 for this process. If you don't have either, check this page:
How-to-Get-the-Right-Testkits-for-your-Pool
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PF => 16

[PoolDoc]

OK. Here's the process:

1. Lower the pH to 7.0 using muriatic acid.
2. Clean your filter. Leave cartridge OUT of filter; leave pump on 24/7!
3. Test the chlorine; add sodium thiosulfate to remove it => approximately 2 tablespoons per ppm of chlorine.
4. Add polyquat, 1 hour after adding the thiosulfate
5. Add 1# ascorbic acid.
6. Check pH; add acid as needed to maintain pH at 7.0 or a little below.
7. Brush stained areas every 4 - 8 hours.
8. OPTIONAL: After 24 hours, if stains are not completely removed, put 1/2 of ascorbic acid in a freezer bag, fill it with enough water to make a slurry, and enter the pool with googles and the bag. Continue with 2nd 1/2# if needed.
9. OPTIONAL: Holding the bag underwater, 'drizzle' the slurry onto resistant stain areas.
10. OPTIONAL: Wait 24 hours more (continue to keep pH down). If stains remain, make an similar slurry with Iron Out, and try again.
11. Add HEDP dose; wait 4 hours
12. Replace cartridge in filter; continue to keep pH low.
13. Begin adding plain 6% household bleach, 1/2 gallon every 2-4 hours, till you have a measurable chlorine level. Try not to exceed 5 ppm.
14. Place CuLator baggie in skimmer.

Notes:

• With your alkalinity as high as it is, your pool's pH is likely to want to rise. Be diligent about keeping the pH below 7.2.
• Once you begin this process, leave your pump on 24/7 for the next month.
• Adjust your pool return eyeballs so the return stream(s) is/are NOT directed against any pool surface.
• Once you have the CuLator in the basket, you can gradually begin bringing the FC level up to what it should be -- 5 - 10 ppm, given your CYA level.
• Once you have a FC level of 2 ppm or higher, you can resume swimming.
• Once the chlorine level is normal, use borax, 1/2 box at a time, to raise your pH to 7.6 - 7.8.
• Once your pH reaches that level, switch from bleach to the cal hypo. (instructions below)
• Watch your filter pressure: once you switch to cal hypo, you may find that your pressure builds up quickly. This is GOOD -- but you'll need to clean the filter every time the pressure goes up by 7 - 10 pounds.
• You can dose your pool to 10 ppm FC, and let it drift down to 5 ppm before adding more.
• Using the CuLator *and* cal hypo added in the manner described is sort of a 'belt & suspenders' approach. Hopefully, the CuLator will work as well as advertised. But if not, the cal hypo slurry on your filter will ALSO tend to trap any metals in the water, and when you clean your filter, these metals will be removed from the pool.

To add the cal hypo:

• Remove the CuLator baggie from the skimmer.
• Make SURE there are no other chemicals in the skimmer.
• With the pump running, add the cal hypo (1/2lb per dose) directly to the skimmer, with the pump running.
• A single 1/2 lb dose should add about 5 ppm FC.
• After all the cal hypo is gone from the skimmer, replace the CuLator baggie