Pool green for over a year.

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My wife & I went over & saw the pool today. She needs a new weir door & pressure gauge. We put a hose over the return and filled a bucket about 2/3 full of filtered water. As you can see it's almost as green as the water in the pool. The filter is a Tagelus TA60 sand filter. I tried to get a look at the sand but the waste line is pvc without a union.
Below is the pressure gauge with pump off followed by pump on.
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Here's a picture of a pail of water from the return after filtering.

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Mike1162 said:
We put a hose over the return and filled a bucket about 2/3 full of filtered water. As you can see it's almost as green as the water in the pool.
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That's to be expected, sand and cartridge filters do not filter out live algae.

The extreme nature of this bloom is going to make for a considerable SLAM. The bromide in the water also complicates matters. There's a lot of very understandable reluctance to a major water exchange but to attempt the SLAM Process would be very intensive and costly and once successfully completed the remaining bromide in the water might force a water exchange regardless.
 
Mike1162 said:
But they'll filter out dead algae? Do the algae 'particles' get bigger post mortem. I'm not doubting you, just trying to understand.
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It's more of a speed thing. It takes several passes through the filter to get enough out to notice a change in the water. Live algae tends to reproduce faster than this can happen though. So even though you clean out green filters, you don't see a change in the water.

When the algae is dead it's not multiplying, so you see the amount in the water getting reduced. So it's my mistake, I simplify it by saying it doesn't filter it out when it's more that it just won't make any difference until it's dead.
 
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The pool is 40 some years old (might have said 49) & she is the original owner. She didn't remember how old the liner is but probably 10+ years. She's quite certain the liner wouldn't survive being drained.

Very unusual woman, in a good way. How many 80 (my guess) year old women have a Shelby Cobra replica that they drive in the summer. She even helped build it.
 
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Mike1162 said:
The pool is 40 some years old (might have said 49) & she is the original owner. She didn't remember how old the liner is but probably 10+ years. She's quite certain the liner wouldn't survive being drained.

Very unusual woman, in a good way. How many 80 (my guess) year old women have a Shelby Cobra replica that they drive in the summer. She even helped build it.
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Mike you are in the ballpark! She's 87! Tough ol bird!
 
“Breakdown” is not really accurate.

The simple answer is that thiosulfate is a reducing agent and bromine is fairly easily reduced. The reaction, a redox reaction, forms tetrathionate and bromide, something like this:

2 S22O2−332− + Br22 → S44O2−662− + 2 Br−−

I understand that much, don't understand what tetrathionate and bromide might react with in the pool.

I think, after you reduce the bromine to bromide, the addition of chlorine produces bromine (Br2):

Cl2 + 2Br-- → 2Cl- + Br2

So you are likely back to square 1 when you add the Chlorine to sanitize. Genes the recommendation to drain.

I hope others with more knowledge will chime in...
 
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I picked up 10 gallons of 12.5% & went over to test the water. Basic kit showed No Chlorine & PH @ 8 or 8.2 so we didn't test any further. Results after adding 1 gal. of Muriatic acid & 4 gallons of chlorine:
PH 6.8 (shouldn't be that low, might have need more time to circulate)
FC= 1.5
CC= 2.5
TA= 60
CH = 500
CYA = 0

Added another 2 gallons of Chlorine:
FC= 1.5
CC= 4.0

Pic from this morning. Foam is gone but green is one shade lighter at best.

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mknauss said:
Foam could also be from the CYA being consumed by a bacteria creating ammonia.
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This is very likely what happened.
Nachos73 said:
I read that sodium thiosulfate can breakdown the bromide. Would this work?
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No. It won't do anything to the bromide.
Nachos73 said:
I'm hoping the pool store can test for bromide.
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No.

If you have ammonia, it's going to be a longer SLAM than it would be without the ammonia.

It's going to be long anyway, but the ammonia makes it worse.

One sign of ammonia is that the pH and TA will drop as you keep adding the liquid chlorine due to the released hydrogen ions from the ammonia.
 
Oxidizing ammonia creates acid by releasing hydrogen.

More than 95% of ammonia is in the form of the ammonium ion (NH4+)

2NH4+ + 3OCl- --> N2 + 3H2O + 2H+ +3Cl-

When adding 12.5% sodium hypochlorite (liquid chlorine) to a pool to oxidize ammonia, every gallon of liquid chlorine will create the equivalent of 15 ounces of 31.45% hydrochloric acid.

10 gallons of 12.5% liquid chlorine added to 25,000 gallons of pool water with ammonia will lower the TA by about 23 ppm or the equivalent of adding 150 ounces of full strength 31.45% muriatic acid.

Every 8.53 gallons of 12.5% liquid chlorine is equivalent to about 1 gallon of 31.45% acid.
 
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So I'm trying to understand the chemistry at work here.
You need to add enough chlorine to convert all of the available bromide to bromine,
then,
continue adding chlorine to take FC level up to SLAM?
 
It's confusing but whether it's chlorine, bromine or some combination of both it will still sanitize the water. It's my understanding eventually the bromide will outgas but that could take years. The best solution is a complete drain but we don't dare risk losing the liner.

I'm kind of winging it, hoping to get it clear enough to see the bottom. Once that happens I'll vacuum to waste then we'll see about draining a few feet of water.
 
Not much can be done about bromide other than trying to dilute it over time.

I would switch to a SWG so that it can keep a continuous amount of bromine/chlorine in the water and it will likely work as long as you can keep a level of 1 to 3 and pass an OCLT.

If the amount of bromide begins to get really low, you will see a gradual increase in the steady state equilibrium amount of chlorine/bromine.

For example, if the bromine is steady at 2.5 ppm for weeks at a specific SWG output, and the level begins to go to 3.0, 3.5, 4.0 etc. it's likely that the bromide is almost gone.

Keep the CYA at about 60 once the SLAM is complete and you begin regular operation.
 

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