Testing out the Culator...

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T

TreeFiter

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In The Industry
Jul 2, 2012
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Saugerties, NY
So I've seen a few posts where a product called Culator has been discussed. I haven't seen anything where it has been approached scientifically, and I happen to have two pools with iron issues that I can experiment with. Both pools have extensive iron staining on the liner, stairs, skimmer plates, and return jets. I intend to do an Ascorbic Acid treatment and add a sequestrant to get the stains off, and then I will try the Culator. I just ordered an iron test kit so I can monitor any progress along the way.

I plan on testing the iron before I do anything. Test it again once I do the AA treatment, and several times in the days following. Then I will put the Culator in the skimmer and test weekly.

Does anyone have any thoughts before I get started?

I'm also playing with a few other ideas. One of them is to use a garden hose iron filter, and attach it to the return jet. The filter is rated to filter 8000 gallons, and one of the pools is about 13000 gallons. If the filter works, it should cut the iron down by at least half. I might even try two filters connected in parallel to double the capacity, and allow for better flow.

Another involves building an aeration chamber, but I'm not sure what to do with that one yet. I've heard people using pillow stuffing, which might be a good idea, but I was also thinking about running the water through something like ping pong balls so as it is aerated, there is significant surface area to deposit iron on.
 
I look forward to seeing your results. Several people have started similar projects, but none of the ones I know of ever finished and reported clear results. One problem seemed to be that the iron test wouldn't always report plausible readings.

The garden hose iron filters have been tested fairly throughly. Under ideal conditions they seem to be able to remove roughly half of the iron passing through. That means you will only remove 1/4 of the iron from the pool. They also only work well at very low flow rates.
 
I'm already a bit discouraged. My Iron test kit is on its way, but I had to get moving on the first pool. I took water samples to a local pool store and had them tested. The first sample was taken before I did anything. The second was taken after I added Stain Free and watched a significant amount of the iron staining vanish before my eyes. Both samples came back with no iron. I never liked this pool store, and now I have yet another reason not to like them. I have very little confidence in anything they do. Hopefully I see more reliable results when I get my own test kit.
 
I'm starting to think that it might not be possible to get precise enough test results to tell if there is any difference before and after using Culator. So far, I had samples come back with no iron when tested by a pool store. They were the first two samples taken, one before stain removal, and one several hours after. I was expecting to see very little iron in the first sample, and more in the second, as it now contains whatever iron was tied up in the stains. Both came back zero, but I suspect the results might have shown slightly more, but the pool store employees weren't exactly taking their time and being careful.

I took a third sample the following day, hoping to see more iron after the stains had more time to dissolve. This time I took the sample to the pool store I work for, and I tested it myself using a La Motte test kit accurate down to about 0.1ppm. Sure enough I got a reading of 0.1ppm. Unfortunately, this isn't going to be too helpful, unless the Culator eliminates all of the iron.

I collected another sample today, and I'm planning to test it tomorrow. I'm hoping this sample shows significantly more iron. The previous samples were after partial stain removal. Today I did another treatment, and lifted far more staining off the liner. There should be significantly more iron in the water now. I'm hoping to see a high enough concentration that it might be possible to measure a drop in iron after using the Culator.

It feels like the levels we are dealing with need to be measured in ppb, not ppm. Realistically, we can't do that without some really expensive equipment.
 
It takes levels above 0.4 ppm to cause stains. If the stains were just removed, the level must be at least that high. I think it is more likely that the test isn't showing iron. Problems with things interfering with the test are fairly common.
 
JasonLion said:
It takes levels above 0.4 ppm to cause stains. If the stains were just removed, the level must be at least that high. I think it is more likely that the test isn't showing iron. Problems with things interfering with the test are fairly common.
Click to expand...

I remember reading somewhere that the tests should show total iron eventually, but it will take longer if there is sequestrant working. I'm wondering how much longer, or how to get a better reading. I'll see what the test shows tomorrow.

I suspected that there should be fairly significant amounts of iron for any notable staining. Here are some pictures of Before and After stain removal. I think this would qualify as notable staining.

http://s104.photobucket.com/user/TreeFiter/media/20140714_121106.jpg.html

http://s104.photobucket.com/user/TreeFiter/media/20140716_181150.jpg.html?sort=3&o=0
 
Wow. That is some serious staining. What is interesting to me is with all that staining, your water still remains very clear.
When my stains start to return, for some reason my water begins to discolor as well. Almost becoming an orangish brown. The Sequestrant / ascorbic acid immediately removes the stains and clears up the water both...

If you can't seem to get an iron reading on a test (a complaint I seem to hear from people more often than not) it might be worth it to test the culator visually instead of 'scientifically' :) That is sort of where I am now. I purchased 2 of them. I am going to put 1 in each skimmer and see if my pool requires less treatments in order to keep the stains away over time. If I see even the slightest improvement, I will keep replacing.
 
mitch08 said:
Wow. That is some serious staining. What is interesting to me is with all that staining, your water still remains very clear.
When my stains start to return, for some reason my water begins to discolor as well. Almost becoming an orangish brown. The Sequestrant / ascorbic acid immediately removes the stains and clears up the water both...

If you can't seem to get an iron reading on a test (a complaint I seem to hear from people more often than not) it might be worth it to test the culator visually instead of 'scientifically' :) That is sort of where I am now. I purchased 2 of them. I am going to put 1 in each skimmer and see if my pool requires less treatments in order to keep the stains away over time. If I see even the slightest improvement, I will keep replacing.
Click to expand...

The pool in the pictures had the stains by the time I got to it. When the water turns brownish, that is when the iron in the water is being oxidized and is forming microscopic rust crystals. Often instead of turning the water brown or rusty, the water will have a yellow or even greenish tint, but will remain very clear. When you add the Ascorbic Acid, it dissolves those microscopic crystals. The only difference with staining is that the crystals are growing on surfaces like your liner instead of floating freely in the water. The strange thing about this pool is that it never had iron problems until now.

I had thought about the approach you are suggesting, but the problem is that even if the culator comes out looking rusty, there is no way of knowing just how much iron that took out. It opens the door to blindly throwing $30 into your skimmer over and over again without knowing how many times you will have to replace the Culator before your staining problems are solved. It is certainly better than nothing, but I'm really hoping to get some answers that could help make decisions like; is it worth draining and refilling the pool, or can iron be removed by Culator for less money.

In any case, I'd be happy to hear how it works for you too. I'll be testing it out either way.

A thought regarding whether your pool requires less treatments in order to keep the stains away over time. You might want to keep track of your chemistry while you test, especially pH and Chlorine. I'm thinking if you create an oxidizing environment, you will tend to promote staining, which would signal you to add more sequestrant. The opposite would be true if you let your pH fall and are able to maintain lower FC levels. So you might have to go through and make adjustments based on what was going on with your chemistry to get an accurate read as to whether or not it is the Culator working, or just swings in chemistry. I could be wrong on this, but this is just what popped into my head as I read your post.
 
TreeFiter said:
The pool in the pictures had the stains by the time I got to it. When the water turns brownish, that is when the iron in the water is being oxidized and is forming microscopic rust crystals. Often instead of turning the water brown or rusty, the water will have a yellow or even greenish tint, but will remain very clear. When you add the Ascorbic Acid, it dissolves those microscopic crystals. The only difference with staining is that the crystals are growing on surfaces like your liner instead of floating freely in the water. The strange thing about this pool is that it never had iron problems until now.

I had thought about the approach you are suggesting, but the problem is that even if the culator comes out looking rusty, there is no way of knowing just how much iron that took out. It opens the door to blindly throwing $30 into your skimmer over and over again without knowing how many times you will have to replace the Culator before your staining problems are solved. It is certainly better than nothing, but I'm really hoping to get some answers that could help make decisions like; is it worth draining and refilling the pool, or can iron be removed by Culator for less money.

In any case, I'd be happy to hear how it works for you too. I'll be testing it out either way.

A thought regarding whether your pool requires less treatments in order to keep the stains away over time. You might want to keep track of your chemistry while you test, especially pH and Chlorine. I'm thinking if you create an oxidizing environment, you will tend to promote staining, which would signal you to add more sequestrant. The opposite would be true if you let your pH fall and are able to maintain lower FC levels. So you might have to go through and make adjustments based on what was going on with your chemistry to get an accurate read as to whether or not it is the Culator working, or just swings in chemistry. I could be wrong on this, but this is just what popped into my head as I read your post.
Click to expand...

Good luck with your testings. I really hope you continue to post on the issue as you go through it. Ive gained a ton of knowledge from reading everything you are saying about this.
 

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So, I went back to the pool today, and I was very pleased to see that about 99% of the iron stains were gone. I added more Polyquat and a Sequestrant, and I turned the chlorinator back on. I took another water sample, thinking that all of the iron is now dissolved, so I should see the highest result yet. I tested the water, and it showed slightly above 0.1ppm. Thats about the same as before removing the stains and during the stain removal. There must be more iron in the water than the test is showing, but how do I get the test to agree?

I also took some of the sample from yesterday and tested it this morning. I kept the vial with me all day hoping that if I let it sit long enough, it might show a more complete result. It didn't. It was still 0.1ppm after about 8 hours. I thought maybe if I added chlorine to the sample to promote oxidation it might help. I added a few pinches of dichlor, and tested again. Still 0.1ppm. I just can't seem to get a test result that even suggests there is enough iron to be concerned.

At least I can take comfort in the fact that the pool now looks like this...
20140717_145159.jpg
 
OK, this problem with testing for iron is driving me nuts. I called an environmental lab today, and they can run samples for total iron for $22each. I'm thinking it might be worth it just to have peace of mind. I was hoping to be able to track the progress after each week, but that would get pricey. I might have to settle for a sample after lifting the stain, and a sample after a month with the Culator in the skimmer. I guess $44 is still better than what I would have payed for a new test kit that might not have even worked anyway.

When I talked to the lab, they said they digest the samples in nitric acid which will pull the iron away from the sequestrant and oxidize it. I'm wondering if adding a strong acid might help the LaMotte test kit "see" the iron in the sample.
 
I think part of the problem is the addition of the polyquat and sequestrants.

Typically, a test reagent will react with a specific ion species when the reaction is free to proceed. A sequestrant, by it's very nature will bind up the metal ion in question and keep it from reacting. That's exactly what it does in order to keep stains from forming - the chemical reaction that would normally cause the Fe2+ or Fe3+ ions to react and form an iron stain (Fe2O3) is slowed because the sequestrant exerts a greater chemical affinity for the ion.

So it may be that the sequestrant stops the iron indicator reaction from happening.

(In my best Princess Leia voice - "Help us Obi-wan Chem Geek, you're our only hope...")

PS - As they say on this forum often, that water has a serious case of sparklipoolitis!!!


Sent from my iPhone using Tapatalk
 
It depends on the reagents used in the test. Better tests will use reagents that very strongly bind to the chemical of interest so use of a sequestrant won't matter unless the sequestrant is more powerful at binding. Most sequestrants have limited binding capability.

So the key is 1) the equilibrium between the free metal ion and that bound to the sequestrant and 2) the reaction rate for the chemical releasing from the sequestrant. Even if the equilibrium is such that there is somewhat strong bonding, that won't matter if the reaction rate going back and forth in the equilibrium is fast. This is what happens with chlorine and CYA. Even though most of the chlorine is bound to CYA, the reaction rate is fast enough that about half the chlorine is released through CYA via a circuitous reaction where half is released every 0.25 seconds. This is why the FC test measures both the bound and the unbound chlorine. However, it doesn't measure the more tightly bound chlorine in Combined Chlorine (CC) because it gets released more slowly though at sufficiently high levels for certain types of CC there can be enough released to "bleed through" to show up as FC.

Now even ferric ion (Fe3+) is bound to some sequestrants, just not as strongly as ferrous ion (Fe2+). So I'm not sure if the nitric acid will work completely. I suppose you'll see.
 
I'm starting to think that an accurate test of the Culator is probably not going to happen. Even with the use of sequestrants, I'm noticing some of the iron staining returning to the liner surface, which means if I want an accurate result after using the Culator, I would have to do another ascorbic acid treatment. Between the AA, Polyquat, and Sequestrant, I'll be out $100 in chemicals, and still could be juggling a pool with iron issues.

The Culator may work to some degree, but I don't think I'll be using it in the future. It does not seem to be a quick fix for iron problems.
 
https://www.youtube.com/watch?v=_f7DQgbmmr0

I just happened to stumble across this video today. This guy seems to believe the Culator works. I do see some iron staining on the bags, but I would imagine that if I left a piece of cloth in the skimmer, it too would stain over time. I'm not convinced that the video confirms that the Culator works, mainly because of the issues I have encountered with false readings due to sequestrants.

The part I found most interesting, as I haven't heard this before, was the part about the Calcium Hardness test indicating the presence of other metals. I did see a purple color change instead of blue with one of the pools I've been dealing with metals in. I'm wondering if there is something to it. For that matter, he uses the Taylor kit, but I'm using the TF-100. Do they both use the same reagents for Calcium Hardness?
 
A piece of cloth might capture rust particles but you'd see that in a pool sweep bag as well. The CuLator staining is deeper and you can cut open the bag and see the plastic balls inside with a deeper darker color.

We have many different threads here about the CuLator. Metal Stains is the most recent. The technology is sound and apparently used commercially so perhaps we'll find a less expensive source for the metal-binding plastic polymer.
 
I meant what I wrote -- the technology is sound. Whether that means it works well in a pool environment with the CuLator bags, that's another story where we have mixed results reported. If a far less expensive source of the plastic polymer were found, then perhaps it could become more economical.
 

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