My Iron Stain Removal

[RPSalty]

I could not find my answer, so a new thread.

Iron staining verified per the vitamin C tablet test. Over the years, when adding muriatic acid, I used a PVC pipe to concentrate the acid on the pebble surface. This would result in bright clean spots. Over time, this has created quite an ugly look.

Per TFP reading, I am in the middle of the ascorbic acid method. I used 2lbs all at once. The SWG is turned off. Pool temp is 72 degrees F. I've added Suncoast Algaecide (always have being a recent PAP devotee). My metal control has been Suncoast Ultra Mineral Control. (I am changing over to the SC-1000 after I finish the bottle.)
Before readings:
PH 7.2
FC 0, CC 0
CH 450
TA 110
CYA 50

Shortly after adding ascorbic acid I tested PH and Chlorine
PH 6.8, FC 0

14 hours later the staining is dramatically reduced. Thoroughly brushed. There was also 1/2 of rain, acidity unknown.
PH 7.2
FC 0, CC 0
CH 400
TA 70
CYA 50

My dilemma: Why did the PH increase? I am tempted to add more ascorbic acid but it will take me 2 days to get it. Can I keep the pool at those readings without damaging the pool surface or hardware? I would have thought 2lbs with my size pool would have been enough. I took care not to overdose because I read that could make it difficult to rebalance.

 

[JoyfulNoise]

You can’t leave the water with zero FC that long. You will get algae abs then you will have to SLAM which will bring the stains right back. You need to exit the stain removal and start rebalancing to bring the FC up slowly. Otherwise if you raise FC too fast, the stains will reappear.

 

[RPSalty]

Okay, I am nervous about the FC 0 as well. Since I've been doing my own testing I can't remember the last time I've had algae. So even though I am using the algaecide, it's best to move on and treat again another time?

 

[RPSalty]

@ 1700 subscribed to the android app. @ 1800 added 4oz algaecide, 4oz ultra metal control, 2lbs baking soda, turned on SWG to 40%. @ 2000 tested for TC=trace, PH=7.2. Water is slightly cloudy. Not enough light to tell if any staining reappearing.

 

[JoyfulNoise]

Use bleach or liquid chlorine to increase your FC. The SWG adds chlorine too slowly for rebalancing.

 

[RPSalty]

@0700 FC=1, PH=7.3
@1200
PH 7.3
FC 1, CC 1.5
CH 425
TA 80
CYA 40
There has been 1" of rain, acidity unknown
Water is clear, no change in staining - still looking good; added 22oz of Chlorine (10.5% several months old), 4oz of algaecide and 6oz of Ultra Metal Control. Filter pressure is up 5lbs.

 

[JoyfulNoise]

Your high CC’s can be from the ascorbic acid reacting with the chlorine but may also be from the metal sequestering chemical. What is the main ingredient of “Ultra Metal Control” ? And what algaecide are you using?

 

[RPSalty]

Both products are Suncoast; the algaecide I think is the equivalent to Polyquat 60, the ingredients are the same. The Ultra Mineral Control doesn't list the ingredients but has "phos-stop plus". I am just trying to use it up, switching to SC-1000. My bad on CC, I've been typing TC numbers. I plan to discontinue using algaecide after the FC is up to recommended level. I should note that I am not a responsible brusher. I rarely brush because the Great White pool sweep has brushes on it. The pool is open, no lanai , but the configuration of two skimmers on rounded sides keeps pretty clean.
@1730
PH 7.4
FC 1.5, CC 0.5
CH 425
TA 80
CYA 40
Water is clear, no change in staining, there's been about another 1/10th of rain. Overcast, minimal sunlight; Letting the pump circulation turn off for the night.

 

[RPSalty]

@1100ish
Latest Test Result Summary:
FC: 0.5
CC: 0.5
pH: 7.3
TA: 80
CH: 425
CYA: 40
SALT: 3000
TEMPERATURE: 75°
CSI: -0.38
Added 32oz chlorine, 4oz mineral control, 4oz algaecide, increased SWG to 80%.
Water clear, extremely pleased with stain removal. Hopefully FC will not rise too fast but I am realizing the challenge of getting it up.
Pollen season!

 

[JoyfulNoise]

I believe the mineral control is causing you problems because it’s not HEDP based; it’s either citric acid or EDTA. Both of those are going to eat up any chlorine you add and the algaecide is going to cause further FC loss. I suggest you stop adding the mineral control or switch over to an HEDP based one. You can keep the algaecide additions but once you get up to the correct FC minimum I would stop that too. You’re just running in circles.

 

[RPSalty]

We'll shoot, I bought a gallon of sc-1000 for metal control. Now I read that it will bring the FC down.
I did expect difficulty bringing FC up after the ascorbic acid treatment, according to the articles, it's expected. The sc-1000 was also suggested in the article. I'll soldier through the gallon.

 

[RPSalty]

K-1000 test, chlorine a little above 1, pH 7.3. Added 32oz chlorine and nothing else. Water still clear but slightly milky. SWG at 80%. Vacuum ran all day for leaves, it is blowing and the oaks are shedding. No rain. Pump shuts down @ 1800, I'll defeat that for a few hours to mix the liquid chlorine. The stain removal is still satisfactory.

 

[RPSalty]

This morning,
FC: 2.0
CC: 0.5
pH: 7.4
TA: 90
CH: 425
CYA: 40
SALT: 3000
TEMPERATURE: 76°
CSI: -0.21
The pump was off all night, I am surprised to see the TA up. The water is clear, no milky. It's overcast and disappointingly I can see the old staining. It could be a sunlight thing and not so noticable in bright light, as I was very pleased yesterday.
After I brush and vacuum the leaves I'll be backwashing so I can add stabilizer. I am going with 4 lbs even though the app asks for 5+.

 

[JoyfulNoise]

Since this was iron staining, did you add any poly-fill (pillow stuffing) to the skimmer basket to help capture any iron that might be filterable? As you raise FC, the iron might start coming out of solution and poly-fill can help to capture it.

Do you know the source of the iron staining? Are you on well water or municipal? Do you know the overall iron levels in your fill water?

 

[RPSalty]

I did not use poly-fill. I was under the impression the filter would capture the sequestered iron. My staining is old. Pre auto fill days (added when the pool was re-surfaced) we used a hose into the skimmer. The back wash would come out orange. Now back wash is greyish, depending on how long I let it go.

I am on a shallow well, the water is between 1-2 on the iron scale. I have an iron filter before the water softener. The auto pool fill comes off of the iron filter; the iron filter removes all the iron (so my water treatment guy says). When the auto fill was installed, there was no iron filter and there would be bright dripping staining at the inlet pipe. Now that the water is filtered, that staining doesn't happen.

The sun came out and the staining is not as visible. I believe the ascorbic acid lightened the stain considerably. The plastic main drain covers and filter baskets look brand new now, they were reddish.

I already bought a gallon of SC-1000 as it was part of the process I am following to remove the staining. I do not believe it is HEDP based, but the ingredients are "proprietary". Also states it will kill the chlorine so I'll keep adding liquid chlorine as needed.

@1730
FC: 0.0
CC: 0.0
pH: 7.4
TA: 90
CH: 450
CYA: 50
SALT: 3100
TEMPERATURE: 76°
CSI: -0.21

You can see I added the qt of TC-1000, FC gone. Added a gal of liquid chlorine and 4oz algaecide. Pool will run overnight.

There is 4lbs of stabilizer in a sock in the skimmer.

 

[AndyTN]

You need to remove the iron from the water or the stains will come back. You can use the polyfil to "absorb" the iron and throw it away or you can do a substantial water exchange if your water is cheap. The iron needs to precipitate to something and the polyfil has thousands of micro surfaces but this takes a while with constant water flowing through it.

I do an AA treatment every spring and currently have polyfil in my skimmer, pump basket, and leaf net on my Polaris. This year I even built a PVC pipe stuffed with polyfil to connect to one of my returns but this is making my pump pressure high so I may have stuffed it too much for good flow. I used to buy the C-u-lator packs but I would rather spend $6 at Hobby Lobby than $50 at the pool store.

Your filter will get some of the iron precipitating in it but if you don't bypass the filter during AA, you likely just released a lot more iron into your pool water. When I do the AA treatment, as soon as I see all the iron stains disappear, I backwash my sand filter for a good hour to release any iron precipitated in the filter.

I am sure you don't close your pool for winter down in FL but do you have a large tarp to cover your pool for a few weeks? With your water temps in the 70's and all the sunshine you get, I would be worried about algae. My water is a lot colder in early spring but I normally do my AA treatment end of FEB and keep on the winter tarp with pump running until April to allow as much time as possible with FC down at only 1-2.

 

[AndyTN]

Your plumbing will also get iron stains all on the inside of your PVC pipes. Below is one of my returns prior to AA treatment. If you don't make a good effort to remove the iron now, you will have just released more iron into the pool than when you started. My water is cheap so I normally do a water exchange of 50-75% right after AA but Memphis water comes from an aquifer which has some iron in it like a well.

 

[RPSalty]

@0800
FC: 3.0
CC: 0.5
pH: 7.6
TA: 120
CH: 425
CYA: 60
SALT: 3100
TEMPERATURE: 73°
CSI: 0.06
Pool surface looks good, the staining observed yesterday morning is not noticeable this morning. All of the red is gone from the surface, skimmers and main drains. It's gone somewhere! I thought to the filter, maybe not so much.

My TA went awry, but this is about the staining. I was aware I would be poking the chemical balance using this stain removal method. I've got to go out for borax, I'll get some poly fill as well... Jumped over to the lowering TA threads, no reason to treat that just yet.

 

[JoyfulNoise]

It’s odd that your TA is all over the place. Unless your fill water is particularly high in TA and you’re adding a lot, I see no reason why it should be going up.

Are you following the test procedures correctly? Are your reagents fresh? Are you using a SpeedStir?

 

[RPSalty]

I am going to test again after lunch, to eliminate operator error. During my filter cleaning yesterday, I purposely only did one quick backwash so I wouldn't introduce fill water. I manually cleaned the filter. My filter is a modified sta-rite DE. Used to have the panels, now it has a cartridge. 60 cubic feet of filtering. 9 1/2lbs of powder.

Last night I put 32oz of SC-1000, 2gal of dated chlorine and 4oz algaecide that may have contributed. I'm also bringing up the CYA, the sock still has a little bit more to dissolve. Probably way too many variables. Plus there's been drizzle rain on and off.

I have a spill over spa, so that adds aeration?? Recently, while I was keeping the FC and CYA low, I needed to add just under a cup of acid a day. My reasoning was I read that high chlorine and high PH can lead to staining. For years this was our case as we only took a sample up to PAP once a week. Now that I am testing myself, sometimes more than once a day, I see the need for acid.

At this point I am happy I have some FC.