Phosphate/Flocculent Trauma

We have recently re-opened a pool that has lain dormant for around 15 years. It is in-ground concrete, and holds about 32,500 gallons. It was repainted completely with SmartSeal paint, and then filled from unfiltered irrigation wells, which we know to be loaded with iron and low in pH.

Repeated trips to the local pool shop with water testing and adjustments have brought us to this point: we've dropped the iron levels down below .2ppm, the pH is hovering at 7.4, total alkalinity is at 90ppm, Calcium hardness is at 240, and CYA is currently showing zero (although a couple earlier tests had it in the 30-50 range--we have not yet added the CYA conditioner that we got for part of the larger regimen when things straightened out.) We are running a Triton T60 325-lb. Sand Filter, and we enhanced with a cellulose filtration supplement while removing the iron (will probably change to DE when that runs out).

The problem began with chlorine levels that would not go up despite shocking with 6 pounds of calcium hypochlorite on two successive evenings after the iron levels came down as well as floating a tablet distributor with six 3-inch trichloro-s-triazenetrione tablets. In addition, when levels weren't going up two of those tablets were crushed and broadcast on the water on each of two successive nights. By the end of this, the water was almost clear, with just a tinge of green haze, but the chlorine levels stayed at almost nil.

After all this, the latest test still showed .5 ppm Free Available Chlorine. They did not report total chlorine. At this point, the pool shop tested for phosphates and found over 1000 ppb. They recommended broadcasting 10 pounds of alum, running the filter to circulate for two hours, and then letting it sit overnight to settle out.

It has now been 24 hours, and the pool is as milky white as when the alum was first added. There was also a green tint to the cloudiness this afternoon, and the pool shop recommended another shock, so an additional 6# of calcium hypochlorite was added. A test strip this evening showed 10ppm chlorine present.

Will the alum cloudiness settle out? (It doesn't appear that there has been ANY sediment settling to the bottom yet, where we're able to see anything.) Should we be doing something else? Do we run the filter if it doesn't clarify soon? Are we screwed? Any suggestions would be MUCH appreciated!

PS -- Thanks for this! It's great to have some access to expert experience and insight that doesn't necessarily have the need to sell you your next quick fix tied in to it!

Did they have you put any sequestering agent in the water? If you didn't I would suggest that you put in a sequestering agent, put more than enough in, according to the directions on the back. You want any metals that are left in the water to be sequestered. Then I would bring my ph down to 7.0 - 7.2, and take the chlorine up to 12ppms with regular household bleach. Cal hypo seems to make it easier for the metals to fall out of suspension. WHile you are raising your chlorine with bleach (pour it in the stream from the return). After you add the bleach, put a trichlor puck in the skimmer of the basket. This will help to let any metals that fall out hit the filter before the pool. Let the pump run 24/7. You will have to test the chlorine frequently, and take it back up to shock every chance you get. Being consistant with the chlorine level with clear your pool up the fastest way.You really need to get a good test kit. Strips have too much of range to test properly. Go to the pool solutions website and read up on pool chemistry. Welcome to the forum.

Cool! Thanks for the input. We did hit it bigtime with sequestering agent (assuming that products called "Pool Magnet" and "Metal Free" fit that category--- over about a week we put in around 4 liters of Pool Magnet, and I think 10 liters of Metal Free.). They helped us get the iron down from around 6-7 ppm down under .2ppm. Copper tested at nothing, and we had our refill water tested and found that iron is not a problem, though that well does show 500 ppm phosphates, so we'll have to keep an eye on that once we manage to get the levels down this time.

So we're going to go with the strong bleach chlorination, checking levels a few times a day to keep it there, and running the filter 24/7, (we're also now adding DE to the filter after each backwash). (The remaining alum in the water won't cause longterm problems for the sand filter, will it?)

And yes, we'll be getting drop test kits soon. So far, most of the test readings are coming from repeated testing at the actual pool shop, where they are doing all the drop tests.

Thanks so much for the reply!