Brown water (indoor Endless Pool)

[EP434]

I'm having a recurring problem with the water in my Endless Pool. Several times over the past two years, the water has developed a brown tint (almost can't see the 42" bottom). Before I discovered TFP, I was following EP's recommendations, which were to keep the FC above 0.5 and to use the Nature2 purifier cartridge, which sits in the skimmer box. Once, an EP tech recommended changing the cartridge filters and "shocking" the water to 5.0 FC and keeping it there until the water cleared. That eventually worked. The next time it tried it, that process didn't work, and I tested for phosphates, which were way over 1000 ppb. (I've heard pool store people say city water is very high in phosphates in my area). I used a copper fungicide and phosphate remover (I don't remember what brand), and the water eventually cleared. After that, I added 3 oz of Pool Perfect + PhosFree weekly (to keep the phosphates in check). The water stayed clear for several months, but the brown returned a month ago. The phosphates again were way over 1000 ppb, so I used the recommended, repeated doses of "commercial strength" PhosFree, but the level wouldn't come down. Algaecide also didn't clear the water.

The pool is indoors (basement), where there is little sunlight and is covered when not in use. I use 8.25% bleach for sanitation.

Here are the test results from last weekend (using a Taylor K-2006 test kit):

FC: 2.0
CC: 1.2
pH: 7.6
TA:75
CYA: 40
CH: 210

Water temp: 84 degrees F.
Pool capacity: 2200 gallons

Last weekend, I decided to slam the pool as recommended here at TFP. Pool Math told me the recommended "slamming" FC level was 17.0. I brought it up to that level and kept it there (testing every 30 minutes, and then hourly after the first night). The FC level dropped quickly at first, but then would remain at around 11-14 after a couple of hours, so I started testing and adjusting the FC four and then three times per day. This morning (about 10 hours after I tested and added bleach the night before), the FC level was 12 and CC was 1.0. The water remains brown, and I'm wondering if I'm on the right track.

Should I continue slamming, or is there something I'm missing? I'm grateful for any help you can offer.

 

[JasonLion]

Welcome to TFP!

I wouldn't spend money on phosphate remover, especially if there are phosphates in your fill water. There is never any need or phosphate remover, and dealing with it they way you have been doing can get quite expensive to little purpose.

I would also avoid any products containing copper, including Nature2 and copper based algaecides. Copper can easily build up to levels where it forms nearly impossible to remove stains. And again, neither copper or algaecide are required and can get expensive.

As of your test results, the FC level was too low. With CYA at 40 you should never allow FC to go below 3. That makes me suspect that you may simply not be using enough chlorine day to day. You also have a CC problem, which should be dealt with as it comes up, and not left to accumulate that high a CC level.

The brown color might be from algae, or it might be from iron in the water. However, iron would not cause cloudiness, so that is either algae or algae plus iron.

It is best to leave the cover off, and get as much fresh air into the room as possible, while SLAMing.

The rapid chlorine loss when first SLAMing clearly suggests that there was (is?) something growing in your water.

Have you been brushing the pool each day while SLAMing?

 

[EP434]

Thanks for the response. I know now (after reading here) that phosphates aren't the real issue. I have no idea how I'd get iron in the water, unless it's an ingredient in the junk the pool store sells. It isn't a problem in the city tap water.

I've also learned that Endless Pools' recommended FC level is way too low, even if the Nature2 sticks really accomplish anything. (And I've stopped using them, too.) I've been keeping the level at around 1.5 to 2 for the past couple of months (before I started slamming).

I've been cleaning the filters daily, and I've been brushing about every 1.5 days.

(I can't leave the cover off long-term without causing moisture buildup in the rest of the house (it's still too cold here to open windows), but I can leave it off for a couple of hours every day.)

So for now should I continue slamming as I've been doing, or should I increase the slam FC target to something more than 17?

Thanks again. I'm very grateful for your help.

 

[tim5055]

Even the largest Endless Pool is 7,200 gallons. You know you have metals and who knows what else form the stuff the pool,store sold you. Have you thought about a drain and refill, starting fresh?

 

[EP434]

Yes, I've thought about that, but I did it a couple of years ago and had the same problem after I refilled it.

 

[EP434]

Just an update: I've continued to slam the pool to no significant effect. Today I decided to bump up the target FC level to 18 ppm. If I don't see any improvement in the next couple of days, I'll consider draining the pool and starting over. Very frustrating.

 

[JasonLion]

Have you done an overnight FC loss test?

Who cloudy/murky is the water (ignoring color)?

How has the filter pressure been behaving, and have you needed to backwash/clean the filter?

 

[EP434]

I haven't done an overnight FC loss test, because the level's still dropping 4-5 ppm every 8 hours or so. The water is a bit less murky than it was a few days ago, and I can see the bottom pretty clearly; it just has a sort of sepia tint. CC has come down slightly, to 1.0 ppm or so.

My filter cartridges just sit in the bottom of the skimmer box, and there's no way to measure the pressure. I've been cleaning them every day, and brushing all the accessible surfaces. I've also run the hydrotherapy jets for 30 minutes about 6 or 8 times a day, and I've uncovered the pool for an hour 2 or 3 times a day.

 

[JasonLion]

Is this pool indoors or outdoors? In an outdoor pool, losing chlorine during the day is normal and doesn't mean anything. Indoors that is a lot of chlorine to be losing at this stage.

 

[EP434]

It's indoors. And I agree it's a lot of chlorine to lose that quickly.