Is this a sane plan?

[zapados]

Is this a sane plan?

I've got iron staining - UGH! Seems like it might be the worst pool issue to have. It's somewhat minor I think...kind of a yellowy browny color on the lighter parts of my vinyl liner. Last summer I went HARD on SLAMing, couldn't budge it. Crushed up vitamin C in a sock and I wiped away a little section. I also have some other, darker stains - maybe they are organic?

Anyways, I'm sick of looking at these stains, so here's what I'm thinking....

Would it make sense to do an ascorbic acid treatment right before closing? So dump that stuff in, let it circulate a few hours to get as good as possible, then partially drain the pool and close it up? Then next year when opening, instead of using the town water directly from the tap, which apparently has a little iron in it, use the "Dual Pentek Big Blue Filter" rig from here Iron Fill Water Filter - Further Reading to do the refill so I get less iron.

Questions regarding this plan:

1. Would leaving AA-treated water in over the winter be a bad idea?
2. How low can I drain a vinyl AG pool?
3. Will the iron that's left re-stain it every year?

It seems like sequestering just sucks...1 mistake with FC and pH and it pops back into your liner meaning the whole treatment was pointless! I'm really looking to get good water in so this isn't a constant fight.

Thoughts?

Thank you for your time.

 

[Texas Splash]

Let's address your 3 questions:
1 - Yes. AA requires the FC to be lowered basically to zero and lower the pH as well. You will want to re-balance those levels prior to closing.
2 - Depends on how low you go and your soil conditions. In general we recommend going no lower than about 18" to 2 ft in an AGP to keep the shell steady and liner tight.
3 - Depends on the amount of iron in the water and the FC/pH levels. Those 3 items together comprise how much the iron will react.

Overall, doing an AA just before closing or immediately at opening in your area is a good idea as water will be chilly (below 60) which helps reduce the chance of algae during the AA. Once you are happy with the AA results, start the re-balance process in preparation for closing. The more water you can exchange at that point the better. I can't speak for the reliability of the Pentek Big Blue Filter. Many people find good success using polyfill to catch iron, but some products do have a finer filtration ability.

 

[Snoobug]

I have iron in our fill water and our sequestrant broke down and some was caught by the polyfill & skimmer sock. The white nylon next to the skimmer is a brand new skimmer sock. I know this isn't what you were asking but it might help in the future with iron issues.

 

[zapados]

Let's address your 3 questions:
1 - Yes. AA requires the FC to be lowered basically to zero and lower the pH as well. You will want to re-balance those levels prior to closing.
2 - Depends on how low you go and your soil conditions. In general we recommend going no lower than about 18" to 2 ft in an AGP to keep the shell steady and liner tight.
3 - Depends on the amount of iron in the water and the FC/pH levels. Those 3 items together comprise how much the iron will react.

Overall, doing an AA just before closing or immediately at opening in your area is a good idea as water will be chilly (below 60) which helps reduce the chance of algae during the AA. Once you are happy with the AA results, start the re-balance process in preparation for closing. The more water you can exchange at that point the better. I can't speak for the reliability of the Pentek Big Blue Filter. Many people find good success using polyfill to catch iron, but some products do have a finer filtration ability.

Awesome responses, thank you!

In response to 1, dang. So if I'm going to rebalance before draining for the winter, I might as well use a sequesterant, right? I don't want the AA process to be undone and have stains re-appear before closing. If I'm going to go that route, than I might as well do the AA treatment ASAP, sequester, and do the drain with the sequesterant in there, and refill with the "Pentek Big Blue" next year to hopefully prevent staining in the future. Thoughts?

 

[Texas Splash]

So if I'm going to rebalance before draining for the winter, I might as well use a sequesterant, right? I don't want the AA process to be undone and have stains re-appear before closing.

I see your point. To be fair, you did note that after a pre-closing AA you would "let it circulate for a few hours". So once the stains were removed to your satisfaction, you could re-balance at that time THEN close. Cold water and perhaps some Poly 60 should keep you algae-free. Remember that even with sequestrant, there's no guarantee you won't have staining since those sequestrants can only last so long. It would be ideal to drain most of the iron water after the AA and have fresh water trucked-in, but that's not always feasible. Between Polyfill and aftermarket products you might be able to keep the existing iron level low enough to not stain in the future.

 

[DorsalSpine]

Texas mentioned this but I'll add my $.02 as well. My well water has a high iron content so my pool water is trucked in. I only use the well water if the rain isn't keeping my water level up. Something to consider vs fighting staining all the time.

 

[zapados]

I see your point. To be fair, you did note that after a pre-closing AA you would "let it circulate for a few hours". So once the stains were removed to your satisfaction, you could re-balance at that time THEN close. Cold water and perhaps some Poly 60 should keep you algae-free. Remember that even with sequestrant, there's no guarantee you won't have staining since those sequestrants can only last so long. It would be ideal to drain most of the iron water after the AA and have fresh water trucked-in, but that's not always feasible. Between Polyfill and aftermarket products you might be able to keep the existing iron level low enough to not stain in the future.

How long does it take for staining to re-appear?

My original hope was to let it circulate with AA then just drain the water and close. But yeah, makes sense it would be a bad idea to leave the AA water in over the winter. I was more afraid that if I took a few more days to balance etc., without using a sequestrant, that could add some stain back to the liner before the closing. Is that not likely?

 

[Texas Splash]

I was more afraid that if I took a few more days to balance etc., without using a sequestrant, that could add some stain back to the liner before the closing. Is that not likely?

It shouldn't take a few days to re-balance. Really only a matter of a day or so. If the stains try to reappear while increasing the FC level (let's say 3-5 ppm), you'll know it fairly quickly before closing. As the AA instructions note, add chlorine slowly, monitor for stains that try to reappear, and add sequestrant as needed to compensate. Use a good Polyquat 60 algaecide to compensate for not increasing the FC really high before closing to help prevent algae. Of course wait as long as you can before closing to ensure the water is cold. As for stains reappearing, it's a coin toss. We know the pH tends to rise in cold water, so that might aggravate the metals. The good thing is that your FC would be low.

 

[zapados]

My final plans to tackle the iron stains....

So I ran the numbers. A partial water replacements should cost me about $34.76. A 2-pack of MM costs $39.44 on Amazon, plus PITA & time. So based on this, I'm going to close almost normally, but lower my water level more than I usually would, targeting that 1.75' area.

Next season, when I open, and I'll try to open early so everything is nice and cold, I'll fill back up to normal with filtered water. Then test FC, make sure it's 0. Then AA and dump back to that 1.75' area. Then raise water back up to normal with filtered water, and proceed with a normal opening. Hopefully the 1.75' that I can't dump out won't have enough iron to noticeably stain the pool and the water going in should be pristine, so maybe this will finally whack my iron issue!

 

[Mdragger88]

Your water supports your walls - it’s not advisable to leave the pool over the winter with such a low water level. Wind, snow,& ice can really do a number on the unsupported walls. Also if you will be using a cover it is designed to be supported by the water in the pool otherwise it will pull on the walls.
If u wish to drain you should also refill asap.

 

[zapados]

Your water supports your walls - it’s not advisable to leave the pool over the winter with such a low water level. Wind, snow,& ice can really do a number on the unsupported walls. Also if you will be using a cover it is designed to be supported by the water in the pool otherwise it will pull on the walls.
If u wish to drain you should also refill asap.

Great point, thank you! You may have saved the life of a pool today, LOL.

Not going to "waste the water" then. I'll just do a normal close to a few inches below the skimmer, than do the drain in the spring after the AA treatment to get that yucky iron water out.