Repeat staining, considering tarp method water exchange

[2WeeksNotice]

Trying to resolve repeat iron & maybe copper staining, so am considering a drain & refill using the tarp method. Have read a lot of the posts and aware of the risks and work. I would consider the no drain exchange, but am on well water. I’ll be using softened fill water and don’t think the softener can maintain soft water for 3-4 days. Will have to stop & regen every 1400 gallons.

Have done AA treatment once each of the past two years and it removes the stains easily. I add Jack’s magic Purple stuff initial dose and then every month add more, but the water line dark tan stains come back eventually, and there is some noticeable stains on steps and the bottom of the pool.

Questions:

• Wondering where the stains come from: for sure, first two summers I added make up water from our well…maybe 500-700 gallons total. One pool store put the iron at 1.3ppm, another had it at 0.9, but not putting a lot of stock in those tests. The white bucket test I did with 3 gal hard water and 1 oz of 12% Cl turned brown almost immediately. The softened water has pool store tested at 0 to 0.1 ppm iron, and passed the white bucket test easily. Not brown at all. On top of this, the PB had a Nature2 Express mineral cartridge in. I removed that during the 2nd summer. So this could be a source of metals. Also, not sure what the winter algaecide was they used when closing 2 seasons. I’ll be closing on my own this year.
• **so question #1 is if all these little things could cause staining?** I’d post a pic, but just used some AA in a knee-high and took care of the waterline.
• Any risks with using the softened well water? I want to make sure it works and make sure it doesn’t have metals. My tests show it is pH 7.9, TA 400, CH 0. Seems pretty manageable? I use this softened water for our 400 gal hot tub drain & fill all the time. I plan to use the hot tub as a test: elevate the chlorine in that to see if any iron comes out of solution onto the fiberglass. If so, it’s easy to fix on the hot tub. If not, I’m thinking it’s pretty safe using the softened water to fill the pool.
• No drain exchange – is the theory once you start, you can’t stop? If so, then that’s where my well & softener probably can’t do that. Hence the tarp method. Just asking this because I think the tarp method is a laborious thing.

I’ve read Dtrav118 post from 2020 and like his methods as well as the siphon idea. I have plenty of vertical drop to make this work. Also read Carlos31820’s posts which had good info.

Yes, it will take a big tarp. Pool is 16x36, 3’ deep to 6’ deep with beach in the shallow end.

Any other thoughts welcome. Thanks.

 

[ajw22]

Sounds like you have iron staining from what you described.

We normally do not recommend the tarp method of draining because of the safety issues with it. A person or child or animal can fall into the pool under the tarp and drown. Be very careful with leaving it in place for any time.

 

[2WeeksNotice]

Pool is fenced, has lockable gates and we are not in a neighborhood. Kids are 17&up. No animals either. Thanks for the reply.

 

[Newdude]

Was it Carlos that sucked out too much and got his pump stuck, or the other guy ? Either way, leave a little old water in the bottom.

And no outside safety concerns is nice but be careful yourself. Of all days to trip out there, you know which one Murphy will pick.

My dog became an instant underwater burrito running across my solar cover. Luckily he was stuck with his head above water because it took 10 mins to get him out.

 

[mas985]

This is just as effective as a tarp:

Refill Experiment

Every year I need to replace at least half of the pool water due to high calcium but this year, instead of a traditional drain and refill, I tried something different. I had read of people doing an in place refill using plastic to separate the new water from the old water. So I thought to...

www.troublefreepool.com

 

[revitup]

I’ve used the tarp method twice now with absolutely no issues.

 

[2WeeksNotice]

This is just as effective as a tarp:

Refill Experiment

Every year I need to replace at least half of the pool water due to high calcium but this year, instead of a traditional drain and refill, I tried something different. I had read of people doing an in place refill using plastic to separate the new water from the old water. So I thought to...

www.troublefreepool.com

Thanks Mark, this might be an alternative. My fill water will be 55-60F, and if I wait a month or so, pool water could be in the 60-70F range. How do I get TDS...is it only salt ppm (I have the Taylor salt ppm salt reagent kit), or does it take into account other solids? If so, is this a pool store test or what? Also, I think my water softener won't allow for a continuous fill: only1500 gal fill, then regen overnight. Seems like this will create more mixing than desired? Certainly seems like dilution would occur, but if I'm going to do this would like to exchange water, not dilute.

 

[mas985]

Thanks Mark, this might be an alternative. My fill water will be 55-60F, and if I wait a month or so, pool water could be in the 60-70F range. How do I get TDS...is it only salt ppm (I have the Taylor salt ppm salt reagent kit), or does it take into account other solids? If so, is this a pool store test or what?

With a SWG, just add Salt ppm + CH ppm.

Also, I think my water softener won't allow for a continuous fill: only1500 gal fill, then regen overnight. Seems like this will create more mixing than desired? Certainly seems like dilution would occur, but if I'm going to do this would like to exchange water, not dilute.

Why not use just the normal tap water? Is it high in iron or something else?

 

[2WeeksNotice]

Why not use just the normal tap water? Is it high in iron or something else?

on a well, high in iron and results in stains...that's why I'm exchanging. So what do you think of the intermittent fill situation & mixing potential? Thanks for the TDS info.

 

[mas985]

It isn't ideal but as long as there is nothing mixing the water, then the diffusion should not be too bad. The larger the temperature difference the better.

If we assume the salt level is 3000 ppm, pool water at 55F and fill water at 60F, that is a delta T of 23F. Let me see if I can run a simulation that will show the amount of mixing that will occur.

 

[mas985]

Have you considered using a pool water RO service?

 

[2WeeksNotice]

I have not heard of this. Does it remove the existing water with iron or treat the new incoming?

 

[2WeeksNotice]

Just googled a little. Not sure anyone around me does this. Central IL near Springfield or Peoria.

 

[mas985]

Just googled a little. Not sure anyone around me does this. Central IL near Springfield or Peoria.

That is the biggest issue. Plus it is expensive and has waste water:

Reverse Osmosis - Further Reading

www.troublefreepool.com

However, you could get your own RO system for the fill water but these tend to be very low flow so refilling would still take a long time. But at least it would be continuous.

 

[2WeeksNotice]

Current water softener does good at removing iron, just that I didn't use soft water to add make up water the first year and got iron in the pool. Currently using rain water (or softened water if no rain) to add. So thinking I just really need this one-time exchange and the iron shouldn't be an issue going forward. Thanks for the ideas.

On the TDS, my salt is at 4000 and CH at 500 currently. Guessing pool temp will be about 70 and fill about 60. So -23 delta T...same as you had earlier. So pump or siphon from the deep end and add in the shallow?

 

[mas985]

So pump or siphon from the deep end and add in the shallow?

Correct.

 

[mas985]

One more thought. You can monitor the discharge water TDS to determine when the fill water starts to dilute the existing pool water (i.e. mixing). I usually will use a TDS meter as that more cost effective and faster for frequent testing than using a drop kit.

 

[2WeeksNotice]

Decided to do the AA treatment for stain removal, then tarp method to drain/re-fill. This will happen in the next month or so before closing. My question now is when the new water is in and tarp is removed and I go to balance the water, do I need any CYA at all to SLAM before closing? Also, my softened well water has tested pH 7.8, CH 0, TA 350-400. Do I need to lower the TA before close, or just the pH?

 

[Newdude]

My question now is when the new water is in and tarp is removed and I go to balance the water, do I need any CYA at all to SLAM before closing?

You'll want 30 CYA. The UV demand has plummeted so there's no need for 70.

If you pass an Overnight Chlorine Loss Test you can skip the actual slam and just raise the FC to 12 for closing. (Assuming you left the CYA at 30)

 

[2WeeksNotice]

At this time of year, what does the 30 CYA do for me that 0 doesn’t? And TA high at close a problem? Thanks.