Sequestrant vs. CYA Bound Chlorine

[calinb]

My recently acquired pool is topped-off with 4.4 ppm iron spring water and has been since it was last filled by tanker truck in 1999 (as far as I can tell from pool logs). Accordingly, I need to learn about sequestrants so I don't make the stains any worse than they already are (especially with a sand filter requiring wasting water to back flush and refilling with spring water)!

Sequestrant instructions appear to want the FC as low as possible (below 3 ppm and ideally at 1 ppm for Metal Magic, for instance). There is no consideration for CYA. Does that make sense? If yes, it seems like a good reason for me to keep CYA on the low end of the recommended range or even a bit lower. I'm currently at 25 ppm CYA and chlorine consumption with a 3.5 ppm FC target is very reasonable. I'm using about 4 oz of a trichlor puck per day and think I'll now switch to LC, given that my CYA level has climbed well above the zero CYA I had when I opened this pool after 4 years of closure.

Thanks for the continuing education here!

Edit: Here's a screen shot of our spring water analysis.
Edit again: Replaced screen shot with .pdf attachment (easier to read).

 

[kimkats]

Here is a bump to get this in front of more eyes.

I like that you are switching to LC now that your CYA is where it needs to be. Good job knowing the tablets add this to the water!

 

[duraleigh]

That's a lot of iron. Is your household water the same? Do you have a whole house softener?

Can't read your water report......too small.

 

[Swampwoman]

Calin b, I cant type much right now due to hand injury but in your shoes I’d cobsider plumbing pool spigot to softened water. My well has 2 ppm iron and is otherwise less than manageable.

For MM, I found it works fine at higher, eg tfp recc FC levels, despite what the label says. I might wear down a bit quicker at our recc levels...but so long as you don’t SLAM Process you should be fine. IME, MM is stronger of the lot, with more active sequestrant.

How does the pool look now and have you tested the metal level in the actual pool?

 

[calinb]

Here is a bump to get this in front of more eyes.

I like that you are switching to LC now that your CYA is where it needs to be. Good job knowing the tablets add this to the water!

Thanks, kimkats!

I made sure I got some tabs without "plus" in them too. It was far cheaper than buying conditioner and LC separately around here--even with the initial higher rate of sun "burn-off" and more frequent replenishment of tabs.

That's a lot of iron. Is your household water the same? Do you have a whole house softener?

Can't read your water report......too small.

I'll try again with the spring water report from Anatek labs (in Moscow, Idaho). A larger screenshot is attached. I'd sure appreciate your thoughts about it.

Yes--same water as household and no water softener. We were on a well before this place where the iron stains in our toilet were much worse. Our toilets here are relatively clean and they are not slimy so probably not iron bacteria. Our current spring water tastes very good too--much better than our old place about 5 hours drive north of here!

I installed two big 4.5 x 20" whole house particle filters in series (one washable 5 micron and one 1 micron, because of our clay subsoil) and an overkill-sized UV sterilizer for "just in case" (because we'll really need a new cistern for next year). The pool water doesn't go through the whole house filters, however. From my limited research, a typical water softener doesn't seem to remove much iron. The ones I saw that claim to remove iron were very pricey. Maybe folks here can recommend a softener for 4.4 ppm Fe!

Calin b, I cant type much right now due to hand injury but in your shoes I’d cobsider plumbing pool spigot to softened water. My well has 2 ppm iron and is otherwise less than manageable.

For MM, I found it works fine at higher, eg tfp recc FC levels, despite what the label says. I might wear down a bit quicker at our recc levels...but so long as you don’t SLAM Process you should be fine. IME, MM is stronger of the lot, with more active sequestrant.

How does the pool look now and have you tested the metal level in the actual pool?

Thanks for taking pains (literally) to reply anyway, Swampwoman! I have an old elbow injury and, can you believe it, I triggered it while brushing the walls of my pool the other day (one brush motion with a twist really got me)!

The water looks nice and clear and fairly blue. I'll try to take some pictures of the stains. (It's cloudy and cooler so I'll probably leave the cover on the pool today.) I did the vitamin C test and it seems to be Fe staining (stain did lighten in the shape of the vitamin tablet). I don't think the stains have grown worse since I opened the pool (was closed for 4 years). I'm just worried about all the Fe in the fill water. Hot and sunny days cause lots of evaporation and my sand filter backflushing has used a lot of water--especially when I was backflushing often to clean the swamp!

I need to take some pictures to ask in the pool construction area about some upcoming repairs anyway. My concrete deck is starting to slope away from the pool.

Does anyone know if these filters work for filling? I've seen mixed reviews on the Culator products here on the forums, but haven't seen any reviews of their fill filters (but then again I probably need to search more specifically for them here):
https://culator.com/product/fillfast-high-flow-pre-fill-for-swimming-pools-home/
https://culator.com/product/fill-fast-pre-fill-professional/

Edit: Screenshots of lab report always look terrible. I hope the attached .pdf is more readable.

Yet another edit: For anyone who stumbles upon my note above about using a UV sterilizer for drinking water in a high-Fe application. I need to remove the quartz tube that separates the UV fluorescent tube from the water about every other month and clean any of the minor stains off of the water side of the quartz tube. (Cheaper UV sterilizers use glass tubes but quartz transmits more UV.) Iron was the reason I got a very large sterilizer, given the size of our plumbing, too. Any iron stains wipe right off the tube with a kitchen scrub pad sponge or even a moist paper towel, but stains will reduce the transmittance of the UV light that sterilizes the water. This is why UV sterilizers are sometimes not recommended for high Fe water.

 

[Swampwoman]

Good morning.

I didn’t have any luck with curator at all. I had some luck with pre-filters...eg big blue Pentec with a reducing filter 25 to 1 micron. But that was on my already-softened water. My dual tank system gets the lionshare of the iron, but not all.

But with 4.4 ppm, I honestly think a dedicated iron prefilter or berm filter would be a worthwhile investment. You will spend as much in a few seasons of sequestrants and those sequestrants will break down into high volumes of phosphate. Phosphates aren’t the boogie man the pool industry would have you believe in terms of algae food, but at super high, eg 25,000 ppm or more, they can cause issues with heaters and saltwater generators.

To manage sourcewater of 4.4 ppm, you’re going to need a lot of sequestrant and need a lot of top ups.

You also have manganese in that water, which also requires sequestrant to manage.

Be sure to keep your ph on the lower side, eg 7.2-7.4 to prevent the metals from coming out of solution.

 

[duraleigh]

From my limited research, a typical water softener doesn't seem to remove much iron

Actually, I think it removes ALL the iron in pool water but, like everything, it has a limited capacity. A water softener is not capable of the volume removal of iron while filling your pool, but it is capable of enough capacity to remove the iron from your fill water. So, eventually, you are left with iron free water.

Generally, most of us believe that iron in it's soluble form cannot physically be filtered out in high volume which makes culator's claims very dubious. Visible iron particles (when your pool turns green or brown) can be physically removed but not in solution in any meaningful way.

Culator's website also seems geared to folks who believe in "magic bullets" to wash away ALL their pool problems away and increases my skepticism. Reports of folks using culator on this forum have not been very positive. I would call them and see if they can explain just how that high rate filter works......I don't understand it.

In short, I believe a whole house water softener is the best way for you to deal with your very significant iron issues.

 

[Swampwoman]

^Whole house softeners are indicated for the up to 2 ppm range, accdng to my water guy, but water techs generally recommend iron specific treatment at higher levels, depending on iron type..

Examples: manganese greensand filters for high iron loads.

Here’s some general info that’s non-commercial: Iron in Well Water - EH: Minnesota Department of Health

 

[PoolguyinCT]

I have 2 Culater fill filters.

They have made pool water in a historically miserable iron count neighborhood easy to service.

I have used them for both filling and recirculating.

 

[duraleigh]

They have made pool water in a historically miserable iron count neighborhood easy to service.

Does culator explain how they work?

 

[PoolguyinCT]

Does culator explain how they work?

Frankly I never explored it. Our town tapped auxiliary wells for city water & the pools look like coffee when CL hits them.

I did a google search for iron mining in the USA.
Michigan was the first search hit, so I reached out to some builders in Michigan & both recommended the systems. On their advice alone I purchased the units & simply enjoyed the results.

 

[PoolguyinCT]

I should add I a using the filter manifolds, not the consumer packs.

 

[duraleigh]

& the pools look like coffee when CL hits them.

Yeah, that makes sense, I think. That is visible iron that has precipitated and decent filters will get that out.

I believe OP's issue is iron in soluble form and I am not familiar with a way to really remove that in ANY volume except ion exchange (water softener, R/O).

Green Sand filters will do it but they have almost no capacity......certainly not enough for a complete fill.

 

[JoyfulNoise]

As Swampwoman indicated, water softeners (those designed to remove hardness, ie, Mg and Ca) should NOT be used with high iron water unless there is an iron prefilter. The ion exchange resin in a softener works by the reversible exchange of ions, that is, sodium ions and Ca/Mg ions can easily exchange with one another based on concetration differences. Unfortunately, transition metal ions (Fe2+/3+, Ni2+, Cu2+, etc) irreversibly bind to the ion exchange resin and then render it useless. So, in a new resin fill, the ion exchange column will remove iron until it starts to saturate at which point it will just pass iron (and Ca/Mg as well) and the resin will be useless.

Iron removal requires either oxidizer injections and [particle filtration (air/chlorine injectors) OR greensand media and potassium permanganate injection (the greensand is a special manganese-iron mineral that catalyzes the oxidation of iron and helps to trap it more effectively). There are iron filters that can be regenerated and ones that cannot. For a high Fe content fill water such as yours, you would need the more expensive regenerating type filter.

FC level will determine how long the sequestrant lasts in your pool water. If your pool water has high FC, the HEDP will be oxidized to phosphate and the iron will become unbound and capable of staining. Phosphates will build up in your pool water over time and then, if algae blooms start to become unmanageable, you may have to treat for phosphates. Phosphates and iron can be removed using alum based flocculants, but that is not an easy process to under take in a pool and can easily cause more trouble.

Long term you need to control water loss in your pool. Keeping it covered as much as possible will reduce evaporative losses and slow the input of fill water. If you can afford to install a rainwater harvesting system, then using collected rainwater will greatly help to keep the pool water low in iron.

Sorry, there are no easy solutions here.

I have commented on the CuLator in other threads and I honestly don’t believe it works. Their chemistry is valid (it’s simply a bag full of ion exchange resin) but the implementation is completely wrong...if it does work at all, it’s marginal at best.

 

[PoolguyinCT]

incidentally I have also seen these in a high end car detail shop.

My problems vanished when I acquired mine.

FillFast Professional Pre-Fill For Swimming Pools - CuLator Metal Eliminator and Stain Preventer

Joyful- break it down for me buddy..

 

[JoyfulNoise]

incidentally I have also seen these in a high end car detail shop.

My problems vanished when I acquired mine.

FillFast Professional Pre-Fill For Swimming Pools - CuLator Metal Eliminator and Stain Preventer

Joyful- break it down for me buddy..

Ok, those are hose-end prefilters and they would potentially work well for removing iron since the water is forced first through a particulate filter and then through the metal ion exchange resin that the CuLator uses. CuLator also sells these entirely useless plastic cages with a small sack of marbles and resin in them that you’re suppose to put in your skimmer or pump basket. That implementation is totally useless as 99% of the water will simply flow around the bag and not through it. In any kind of ion exchange process, water has to be forced through the resin bed in order that the water contacts the resin material and efficient chemical exchange occurs. Otherwise, simply relying on diffusion will not work.

So the product that you list there would be good for a hose end fill. There are also RV style calcium hardness filters that can be manually regenerated and are capable of treating a few thousand gallons of water at a time. Folks that like to hit the road in their RVs use them to avoid getting scale deposit is in their plumbing when hooking up to random trailer park water sources. So, in theory, one could use that iron pre-filter in conjunction with an RV softener to produce some very clean water for pool fill purposes.

 

[PoolguyinCT]

I have also used them after fill.

Like I said I did not examine the workings, bought them on competent Michigan builders recommendations & moved on to my next cycle of torture.

 

[calinb]

Good afternoon everyone!

Good morning.

I didn’t have any luck with curator at all. I had some luck with pre-filters...eg big blue Pentec with a reducing filter 25 to 1 micron. But that was on my already-softened water. My dual tank system gets the lionshare of the iron, but not all.

But with 4.4 ppm, I honestly think a dedicated iron prefilter or berm filter would be a worthwhile investment.
<snip>

To manage sourcewater of 4.4 ppm, you’re going to need a lot of sequestrant and need a lot of top ups.

You also have manganese in that water, which also requires sequestrant to manage.
<snip>

Here’s some general info that’s non-commercial: Iron in Well Water - EH: Minnesota Department of Health

Thanks for typing again with your sore hand, swampwoman. The manganese tested well below MCL levels but the magnesium was 4.44 ppm and my lab report did not list a maximum recommended level for magnesium. I'll look into berm and greensand/permanganate. I've been trying to avoid what appears to be a substantial filter cost in a water softener. The filter systems I found online were well into the $1k+ price range, as I recall but they might be necessary. I know the iron (and maybe the magnesium?) in our spring water is a stain ticking time bomb! At least that MN Dept. of Health paper says the RIGHT softener COULD work for me: Manufacturers report that some units are capable of removing up to 10 mg/L, however 2 to 5 mg/L is a more common limit.

Given that the FE limit is 0.3 ppm, I need something that takes out almost ALL my iron or the water replenishment requirements eventually doom me!

<snip>
In short, I believe a whole house water softener is the best way for you to deal with your very significant iron issues.

Yeah--I'm trending toward that conclusion too, Dave. I skimmed the links chemgeek provided elsewhere on the culator technology and I also suspect the problem with the culator "egg" treatment is it's not actually a filter so the vast majority of the water just takes the least path of resistance and bypasses it, even it it contains a technology that might work in a different embodiment.

I have 2 Culater fill filters.

They have made pool water in a historically miserable iron count neighborhood easy to service.

I have used them for both filling and recirculating.

Thanks for the report, Poolguy! I'm more interested in trying the fill filters than the egg, because I think water just bypasses the egg.

Does culator explain how they work?

I just called Periodic Product (Culator) spoke to Zach. I asked him how their fill pre-filter works. He said the 2nd stage of the fill filter contains the same technology as what I call "the egg." I need to go back and find that link to the patent that chemgeek posted in the forums and study it now. I asked Zach about running a smaller recirculation pump to process my existing pool water through their fill filter too. He said he was thinking about recommending this setup to me and it would work too. I have several large submersible aquarium filters. I'm inclined to use then with the culator fill filters and try this method. My pool pump is 1.7KW single speed so the smaller pumps would save me a lot of electricity! Even though I have a GFI to power them, I'd remove them before swimming in the pool but they could run 22 hours per day, minimum! Zach also said a sequestrant is necessary for their filters to work. I'll look for the reasons behind that requirement when I read the patent chemgeek posted.

If I do this "experiment," I'll probably spend the money for before and after pool water testing and report the results in the forums.

Yeah, that makes sense, I think. That is visible iron that has precipitated and decent filters will get that out.

I believe OP's issue is iron in soluble form and I am not familiar with a way to really remove that in ANY volume except ion exchange (water softener, R/O).

Green Sand filters will do it but they have almost no capacity......certainly not enough for a complete fill.

Reverse osmosis always produces much more "waste" water than "good" water, right? I don't think it can work for me because of that feature. rGeen sand might work to keep my Iron from increasing from fills, however. I am covering my pool religiously, BTW. Can't afford to waste valuable spring water around here!

As Swampwoman indicated, water softeners (those designed to remove hardness, ie, Mg and Ca) should NOT be used with high iron water unless there is an iron prefilter.
<snip>

I have commented on the CuLator in other threads and I honestly don’t believe it works. Their chemistry is valid (it’s simply a bag full of ion exchange resin) but the implementation is completely wrong...if it does work at all, it’s marginal at best.

Thanks for the inputs, Joyfulnoise! I think the "iron prefilter" is what makes the softener systems I looked at so much more expensive.

It's interesting that you agree with chemgeek (the culator chemistry is valid). A true filter appeals to me as being more likely to be efficacious than the egg! But who knows? If I'm going to spend money on an "experiment" with before, during, and after metals testing, I might even run an egg for a month and see if it does anything!

 

[calinb]

I have 2 Culater fill filters.

They have made pool water in a historically miserable iron count neighborhood easy to service.

I have used them for both filling and recirculating.

What kind of pump did you use for recirculating use, Poolguy? Can you describe that setup and flow rate?

I should add I a using the filter manifolds, not the consumer packs.

From the photos on their website, the actual filter elements in both consumer and pro appear to the same; the pro just uses a doubled set. They also appear to be common 4-1/2" diameter x 10" long filters ("big blue" style). Can you confirm this for me too? If that's what they are, I'm inclined to buy the filter element set and put them in my own housings with an aerator on the front end.

Hmm, their website says the carbon prefilter removes CC, but doesn't it remove FC too?

Edit: Or maybe the filter elements are 2-1/2" x 10". Hard to tell from the photos but I suspect they are some "standard" size. Injection molds for custom size filter housings are just too expensive for a manufacturer!

 

[PoolguyinCT]

For the fill I just used city water garden hose.

For the rescue / recirculating I knocked down one of my submersible pumps to filter manifold size.

I did not bother with flow rates. I ran pump for about 2 days.

On the deck I also had a 100sqft auxiliary cartridge, that was just to keep my customers filter clean after I changed blood red sand.

As far as cartridge material, I did not investigate.

Timely & high quality results are my objective, empirical data is secondary. Though I will likely hyperfocus in the Why when the snow falls.