Sequestering agent and brown water

[Chas]

Hi all, I'm a newbie to this forum. I look forward to learning and contributing here!

Dealing with a fresh fill and high iron content. The 20,000 gallon pool was filled with one garden hose at half throttle over the course of 2 weeks through an iron filter that was regenerated every 600 gallons. Roughly 100 oz. of Sequa-Sol were added over time as the pool was filling. After the pool was filled the pH adjusted from 7.8 to 7.4 and the filter was started, pool was shocked with calcium hypo. Of course, the water turned dark brown. Why wouldn't it?

After talking to GLB tech yesterday I'm confused. I've used Sequa-Sol for years in customers' pools for spring openings and top-offs with the idea to reduce or eliminate staining from minerals in makeup water. GLB tech tells me that Sequa-Sol won't remove iron and minerals, it just keeps the molecules in solution so they won't precipitate out with chlorine. So - you can't see 'em but they stay in the pool water. Oh, and this doesn't necessarily "prevent" staining. The pool operator needs to continually add the product in order to keep the minerals from precipitating. HUH?

So. Here's my questions:
1) Does a sequestering agent like Sequa-Sol aid in stain prevention once chlorine is present?

2) With a pool’s fresh fill where sequestering agent is added before chlorine is added, then a day or so later, chlorine is added - After the chlorine precipitates iron into suspension and the water turns brown, does the sequestering agent “lock up” the iron molecules somehow so they’re not able to stick to surfaces and stain?

The pool is clearing up after three days of running and many cartridge cleanings, lots of iron settled out to the bottom. I'll vac it to waste and - gasp - add more water. ugh

Thanks~

 

[duraleigh]

Welcome to the forum.

Let's start with how much iron was in your pool water when you first tested it?

 

[Chas]

Don't know. Lots. pH of the fill water is 7.8 at 410ppm total alk. Last night the water was crystal clear as all of the iron had settled out. I vacuumed to waste without trying to be real thorough, still used about 600 gallons. Then I brushed the bottom as best I could see in the dusk before sunset, the iron brushed right off. Left the vac head hooked up in the deepest part of the dish and it ran all last night and today like that. This afternoon the water was crystal clear, I put my scuba tank on, took a swim and cut in the main drain. this is an above ground pool with an new overlap liner on a hard (vermic) bottom. I couldn't cut the drain in until the pool was full. I brushed the bottom and sidewalls, all the iron came off. No chlorine is present, I added my last quart of Sequa-Sol last night and topped off the pool through the softener/iron filter. A half quart of algaecide and 4 oz. of HTH Clarifier went in this afternoon, pH is at 7.4, I added 2 pounds of GLB Supersonic 73% Calcium Hypo shock tonight. Water looks real good, a little turbid after I brushed it. We'll see what it loks like tomorrow morning!

So - I guess I kind of answered my own question as to how the sequestering agent works without and with chlorine. I added it as the pool was filling and after the two weeks of fill time it must have had plenty of time without chlorine to do its thing. Granted, when the chlorine finally was added the water turned dark brown, so dark I couldn't see my hand at a foot deep. The ugly brown settled in on the nice white brand new wide mouth skimmer I just installed. I was pretty surprised, though, to be able to simply wipe off all the brown and brush all the brown from the new liner. Whew! It seems as though the info I got from GLB tech may have been a little misleading or I just didn't understand. In any event, the water was ugly dark brown Sunday morning and by Tuesday night the water was clear and the iron settled out. Tonight, Wednesday, the water looks close to great. Part of that is due to the inground equipment I have running this pool such as the 100sq. ft. cartridge filter. Yeah, I cleaned cartridges there for a few days! Filters are a whole 'nother topic! Thanks for reading all of this and I look forward to learning and maybe contributing on this site in the future.

 

[BoDarville]

Sequestrants keep the iron/metals from depositing as stains - it does not remove them from the water. As a result, you will need to add sequestrant periodically to keep the iron in suspension.

I added 2 pounds of GLB Supersonic 73% Calcium Hypo shock tonight.

Just be aware that cal-hypo adds calcium to the pool and may cause the water to cloud up for a few days. Also, a one-time dose of "shock product" is a rather pointless exercise - it'll drain your wallet without providing you any benefit. We have a process called the SLAM Process which is used to clean pools contaminated with algae or other organics. Best thing is, if you are maintaining proper FC levels there is no need to SLAM (or shock) weekly or on any other regular schedule. I've gone 4 years (and counting) without SLAMming.

Also not sure why you added the algaecide as some types can add more metals to the water which would exacerbate your problem with metals.

A full-suite of would help.

It sounds like you're following more of what we refer as the Pool Store Method to maintain your pool. You will have to make a choice between that method and ours - the two are not compatible. If you choose to follow ours, you will need one of the Recommended Test Kits. I use the TF-100 because it's the best value and they have a freshness guarantee. You can order it here: TFTestkits.net. They ship fast - you should have it in your hands in 2-3 days with normal shipping.

I would also get an overview of our methods by checking out these articles:
1. ABC's of Pool Water Chemistry
2. Chlorine CYA Chart
3. Recommended Pool Chemicals
4. Recommended Levels
5. Pool Math

 

[JoyfulNoise]

From what you describe, it sounds like your well water is basically pure iron with a smidge of water you probably could have sold all that iron precipitate to a local steel smelter and made some cash. I suggest you find a good lawyer and begin to cash in on the mineral rights your property is sitting on

Ok, ok, enough with the bad jokes. So at any point in this elaborate process of proving that controlled iron scaling is possible, did you ever consider having pool water trucked in? It sounds like you spent a lot of money on all kinds of marginally-useful pool chemicals and hose-end filters (designed for gardening, not pool filling) and got little return on your time and money as you basically scaled all the iron out of your water and washed all the iron scale out of the cartridge filter. Thank goodness you have a vinyl liner as a plaster pool surface would have destroyed by all that iron.

Since your well water is high pH, high TA and high Fe (the perfect storm of bad fill water), you may need to rethink the pool fill strategy. I see you're in Wisconsin, is rain water harvesting an option?

Welcome to the forum


Sent from my iPhone using Tapatalk

 

[Chas]

"From what you describe, it sounds like your well water is basically pure iron with a smidge of water you probably could have sold all that iron precipitate to a local steel smelter and made some cash. I suggest you find a good lawyer and begin to cash in on the mineral rights your property is sitting on"

JoyfulNoise - Yeah, I'd like to find a good lawyer for more than just mineral rights around here! I'm in the heart of farm country, surrounded on three sides by crops. I've had lots of adventures with water over the past 25 years of life with this pool. I try to avoid top-offs! I don't cover the pool in the winter, just garbage vac it after the debris is pretty much done falling in November and drain the lines. By springtime it's full with good water again and I start it up in early April or so.

I'm a liner guy that just replaced my liner here, I didn't want to drop a grand on three loads of water and the access is difficult. So far, I've burnt through $89 (incl freight) in Sequa-Sol and $12 in Clarifier to deal with the bad water fill. The rest - 6 pounds of cal/hypo shock in 3 treatments (I use that in all my customers' pools for spring startup - at 73% CL it's hot and dissolves quickly - other than that I discourage the use of calcium based chlorine), 2 quarts of GLB Algimycin 600 (60% Poly oxyethylene yada yada no copper) a gallon of Muriatic and 10 oz. of Clarifier - I would have used in my spring startup anyway. The shocks been precipitating the iron out nicely, I hit it last night after adding 600 more gallons of makeup water and of course it turned slightly brown by this morning. Patience, I remind myself, pool water requires patience. I'd love to create a rain water reservoir, it just pours out of the barn's downspouts, but it's not terribly practical, may breed more mosquitoes than anything....

BoDarville - "Sequestrants keep the iron/metals from depositing as stains - it does not remove them from the water. As a result, you will need to add sequestrant periodically to keep the iron in suspension" - I get that a sequestrant doesn't remove the minerals, and thankful that it will (hopefully) protect from staining. I think you've answered my question, though, by saying "keep the iron in suspension". That's what happens every time I hit it with shock - the CL precips the minerals out and and sequestrant holds it that way so the filter can catch it or it settles out and can be vacuumed up. No? That's why I've been shocking it every few days. The first shock dropped a whole bunch out, the second shock (to clear water after I vacuumed to waste) dropped very little out and the third shock after I topped it off precipitated the new stuff out. At least that's my theory. Once the chlorine level subsides - probably by tomorrow - I'll replace the filter cartridge again (I soak 'em in Iron Out), vacuum the pool normally, replace the cartridge again and hopefully should be good to go. Fill the SaniKing with 3" Omni TriChlor pucks, add some cyanuric to around 30ppm, adjust the pH again (that will be all summer with a startup of 410ppm Alk) and watch the grandkids clean my pool by swimming in it.

As far as a full suite of tests - I'm anxious to read up on what you suggest. My full suite of testing for way more years than I want to think about is free CL, combined CL, pH, acid demand, total alk and sometimes the level of cyanuric acid. I'm a liner guy, all my in-ground customers have liner pools. I can imagine that liners are a little less picky than gunite/plaster/tile pools, although sure not as beautiful! I worked for a gunite pool company for awhile, they sure do look great!

My tests tonight are 3-5ppm free CL, 7.6 pH, 405 total alk and the water is slightly brown from last night's shock. The filter pressure has been steadily rising so I know it's working.

I enjoy reading the equipment you guys have - Kool Toys! thanks for your feedback!

 

[JoyfulNoise]

I'd love to create a rain water reservoir, it just pours out of the barn's downspouts, but it's not terribly practical, may breed more mosquitoes than anything....

Considering the limited supplies of "good" fill water you have for your pool, and the other uses for rain water, a collection system would seem ideal in your case (assuming you're willing to foot the bill for it). I live in southern AZ and there's lots of great resources here for designing and building rainwater collection systems (and some rebates too). A 1000 gallon holding tank is not nearly as big as it seems and if the rainwater is just pouring out of the gutters...well, that just makes me jealous If you design the system so that you only use it for pool replenishment, then you'd probably have a readily available supply of fresh, calcium-free, carbonate-free and metal-free dihydrogen monoxide...As for mosquitos, they are easily controlled by keeping a holding tank sealed at all times and keeping a small residual of chlorine in the water. Since you live in an area where calcium is not likely a problem, the cistern could have a small cal-hypo puck holder in it or you could just do simple bleach chlorination. Add a good submersible pump with a low-volume float switch and you'd be one cool pool dude

Then, if you had that, you could have a cool pool toy to show off too