Acsorbic Acid Treatment

[RBpool]

This is my first time posting, and I’m new to pool ownership as of September 2017. Until coming across this forum, I was (well, honestly, I still am, because waiting on testing kit to arrive) using Suncoast Multi-Purpose Chlorine tablets. My water looks great overall.

After trying the vitamin C test, I determined I need to do an absorbic acid treatment to return my pool surface to it’s former blue glory. So from what I’ve gathered, this will remove the metal from the surface of my pool INTO the water. Do they remain there forever and I have to use sequestrant for the rest of my life? Can I remove them? When can I adjust water levels following the treatment? Would a drain/refill be better?

I have one of rec testing kits on order, but below are the numbers from the pool store.

From the pool store (last week):
TC: 5 ppm
FC: 5 ppm
CC: 0
PH: 7.8
TA: 80 ppm
CH: 275 ppm
Stabilizer: 80 ppm
TDS: 1400 ppm

thanks!!!

 

[mknauss]

Welcome to the forum!

First, good job in ordering a proper test kit. Be sure to add what you have to your signature.

Second, discontinue using the tablets. Your CYA level is already too high for a non-SWCG chlorinated pool. Also, 'multi-purpose' tablets usually mean they have copper algaecide in them. Which is adding metals to your water.

Others are more versed on the metal staining removal. But normally if you do the AA treatment and put the metals back in your water it is best to remove that water and start fresh.

Take care.

 

[Donldson]

Also, 'multi-purpose' tablets usually mean they have copper algaecide in them. Which is adding metals to your water.

Luckily in this case they do not. The Suncoast Complete tablets actually add borates to the water instead of metals. It is listed as a trade secret, but with the claims of clarifying alongside algae prevention it is almost certainly the case. So good news there, though the borates added are minuscule and won't make a difference before the CYA buildup requires a water change anyway.

But that is just an aside, obviously you have successfully tracked your staining down to metals and regardless of where they came from that is a problem. Marty is spot on, getting that out of the water is a very good idea.

Welcome to TFP!

 

[DeanP66]

Once you get your test kit, run all the tests. If your CYA test is as high or higher than the pool store test, I would do an ascorbic acid treatment, and then drain and refill so you have fresh water. That will solve your high CYA as well. That way, you don't have to sequester the metal because it will be gone from the drain. Then after the refill, after your chemicals are back to normal with your new lower CYA, maybe just use a maintenance dose of sequesterant monthly. You probably only need about 16 oz (half a bottle) to do the trick. It will help fight the stains from slowly returning.

Also, discontinue the use of those chlorine tablets and stick to just liquid chlorine or bleach. Otherwise, your CYA will once again climb requiring at least another partial drain.

I did an ascorbic acid treatment last August and it came out great. Pool still looks fantastic. I didn't do a drain though. I just did the treatment which included:

1) lowering pH to 7.2
2) letting FC drop to near 0
3) added around 5 Lbs of Ascorbic Acid
4) added 2 quarts of Metal Magic metal sequesterant
5) slowly brought the chlorine level back up to avoid algae
6) added 16 oz of MM sequesterant monthly as a maintenance dose

 

[RBpool]

Thanks for the replies! DeanP66, I love your pictures, because the before pic looks exactly like my water, that greenish color has been driving me crazy since we moved in.

My test kit (Taylor 2006) is supposed to arrive today, and I’ll post my results then. Planning on using the Pool Math suggestions and removing the tablets once I have accurate numbers.

I was planning to deal with any stabilizer issue after the upcoming rainy season here in FL (June-September), because I expect a lot of dilution during these months. Is there a reason beyond needing additional chlorine that high CYA is an issue that needs immediate attention? I am also thinking that maybe I can add sequestrant until after then, monitor closely and drain if it becomes an issue again. Tell me if this is a bad idea!

 

[DeanP66]

High CYA isn't the end of the world unless you have algae and need to do a SLAM. Then it can be very difficult to clear and require a ton of chlorine. Your pool looks ok. Just stay vigilant with the chlorine. If your cya test from the taylor kit is around 80 like the store's test and not over 100, you can definitely manage it like you suggest. Just keep that FC in the 9-11 range and never let it get below 6. Just remember that your pH test will not be accurate when FC is above 10.

As far as the AA treatment, you may have an issue. You're supposed to let FC drop near 0 when adding ascorbic acid. The acid will eat away at any remaining FC before it starts to work. You could find yourself susceptible to getting algae once this happens, especially as the weather warms. You could use a bottle of Polyquat 60 algaecide to help prevent any algae from starting. I did mine last August when it was warm (high 70's/low 80's). I actually put in the ascorbic acid with my FC still at 2 cause I couldn't wait any longer. It required quite a bit more than usual because of the remaining FC in the pool. After adding my 2 bottles of MM sequesterant, I started to bring the FC back up slowly. It required a LOT of chlorine to get rid of all the remaining ascorbic acid and start holding near the level to where I added.

Sequesterant by itself can work as well if the stains are very light and not very old. I've seen people on this site have success using it. However, it seems to work best in a vinyl pool as opposed to plaster. One plus side to sequesterant only, is that you don't have to lower the FC at all, so you won't risk getting an algae breakout.

 

[RBpool]

Okay, so here are my numbers today:

FC: 12.5
pH: 7.3
TA: 70
CH: 260
CYA: 80

Im shocked the FC number was so much higher than the pool store told me, but I checked it 3 times on Friday and daily since then. My starting FC was 15 on Friday, and I’m going down about 1ppm each day (direct sunlight all day). Added baking soda to raise my TA, but I only had about a quarter of the suggested amount (per Pool Math) at the house, will run for more this evening.

So, should I do a partial drain/refill, get my numbers right, then lower FC, do the treatment, then drain/refill again...or can I continue lowering the FC and control my water with algaecide until after the treatment is over, then drain/refill? I would like to avoid a drain/refill twice if it all possible.

 

[DeanP66]

I would leave your TA right where it is. With your pH at 7.3, as it climbs, your TA will climb a little with it. There is no need to help the process. From the picture you took, it's really difficult to see the actual stains in the pool. Could you take a better picture in more direct sunlight or from a different angle so we can see the pool a little bit better?

If you're planning on emptying your water after the treatment, I would just let FC drop and do the treatment with the AA. Add the algaecide when the FC gets around 4 PPM and maybe start the treatment at FC 2 so you don't risk getting algae. You will just use more AA which will kill the remaining FC before it starts working on the stains. I would try around 5 pounds if you have any remaining FC left. Let the AA work on the stains for a couple of hours and add your sequesterant. I would go with 2 bottles to be safe. A little extra is better than not enough at this point. Let it work a couple of hours and it should lift the stains into the water. I usually like brushing the AA a little bit especially where the stains are more concentrated. Don't know if that really helps at all, but i feel better about it.

When the stains are gone, start draining. It might also be a good idea to add a gallon or two of liquid chlorine at this time, to further keep any algae away. Refill the pool when it's drained, get your CYA up to 30-50 range and add some FC and adjust your pH if needed. Don't mess with TA until everything else is in range. It might be high from your fill water (mine was 220). I aerated my pool and added MA to lower it again and again until it got to where I wanted it.

 

[RBpool]

Thanks for the advice! Here's a photo...the staining in person looks like an uneven yellow/brown finish. The photo shows you what the vitamin c tablets did (and a stain they didn't touch). I can get a better pic in the morning when the sun is hitting the pool.

 

[DeanP66]

Are those white streaks in the middle of the picture from the vitamin c tablets that you tested the pool with? If so, you can really see the difference. You should have some really good success with the AA treatment. I'm not sure about those 3 little dots. They may just be organic stains. Regardless, your pool should clean up nicely. Good luck!!

 

[RBpool]

Help! So Day 1 of the treatment, and my pool water is green and there are still a few stained areas in the places with poor circulation. Brushing isn't helping. Do i need more acid? I'm guessing drain/refill is the only option for blue water.

You can't tell from this picture but great improvements to pool surface.

 

[DeanP66]

If you have any more AA, you might try adding it over the remaining problem areas that are left. Since you're gonna dump your water and refill, once you're happy with the stain treatment of the plaster, go ahead and empty your water. Use a submersible pump so it will go fast, so you don't give the possible algae any time to grow. Once it's drained, fill it back up, add some CYA to get you to around 30 PPM and do a SLAM. Dose FC to 12 and continue until you pass the 3 criteria for an OCLT (overnight chlorine loss test). Normally, you don't want to SLAM right after a stain treatment, but since you're dumping the water anyway, go right ahead and that should clear the pool right up very quickly.

 

[RBpool]

Oops, should’ve been clearer. Water is green from metals now in the water, not algae. Totally clear green water. But I’m guessing getting the metal out is going to be a larger/pricier process than draining.

Ill add more asorbic acid until stains are gone, assuming such a mild acid will not hurt piping etc.

 

[triptyx]

You'll definitely need to add and maintain a sequestrant for those metals. Do you know if they are present in your fill water or were they somehow added to the pool in the past?

 

[RBpool]

Have a sequestrant in, added more this afternoon which seems to have helped the green situation somewhat. Hope to see more improvement but I might rent a sump pump this weekend.

No metal in fill water. I bought the house in September with metal stains on the surface. The people who owned it before us bought it as a foreclosure and it had sat empty for at least two years. I’m assuming the metals came from that period - there is no pool heater currently but the set up indicates there might have been one previously. This is all large assumptions on my part, of course, all I know is they are from before my time

 

[RBpool]

Well, I had an algae bloom. I’m sure some people are thinking “duh”, but denial is a powerful thing. I think it was a preexisting condition that my high CYA/high FC was masking. Also, the algae was literally the exact same color as my metal stains.

For those reading in the future, here’s lessons learned:
- if there’s a “metal stain” that is not coming off after a few doses of acsorbic acid, try the vitamin C test again before you dump another pound of vit c on it.
-balance your pool water and know your pool before you start something as complex as an acsorbic acid treatment
- if you have high CYA and are impatient like I am, just plan on a total drain/refill immediately afterwards, don’t wait for a more convenient time, the algae certainly won’t.

Anyways, the pool surface looks awesome, except for the parts that don’t

New pool water, adding CYA now, wait 24 hours for it to dissolve or start SLAMing immediately? Scrubbed the empty pool walls so the pool looks mainly okay, but algae is already regrowing. Will post numbers of my fill water and pictures after I get the kids down for naps. Thanks for the help!

 

[DeanP66]

Start the SLAM right away assuming you CYA is at the level you think you added. Don't give that algae more chance to grow by waiting.