Recommissioning a dirty pool

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sirenian

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Sep 27, 2021
7
Boston, MA
I'm cleaning up a 30,000 gallon outdoor pool in MA that sat open to leaves and detritus for around two years. So far, we've have:

  • Replaced the seized pump motor
  • Replaced the the pump seals
  • Replaced the cracked valve innards
  • Replaced leaky glued hard pipe between the pump and filter with new hard pipe and union fittings.
  • Scooped and vacuumed out a thick layer of leaf and algae muck
  • Brushed regularly
  • Taken out the railings and ladders to be scrubbed separately
  • Brought the chemistry to:
    • Alkalinity: 50ppm
    • pH: 7.2
    • Calcium: 275ppm (probably will level out above 300ppm after my final addition today.)
    • CYA: 50ppm
    • Chlorine: shocking 1x/day to 20ppm with cal hypo, losing about 5ppm per day now. No CC registering at the moment. We're about to use up our 50lb bucket.
Our assumption, up until now, was that the pool was too dirty to start a real SLAM.

Now, the pool water is blue, but quite hazy. We'll switch to bleach one the cal hypo runs out, and start a SLAM. I'm hoping that the haze will dissipate both from clearing out any algae and stopping cal hypo use.

Is there anything else we should be doing?
 
sirenian said:
I'm cleaning up a 30,000 gallon outdoor pool in MA that sat open to leaves and detritus for around two years. So far, we've have:

  • Replaced the seized pump motor
  • Replaced the the pump seals
  • Replaced the cracked valve innards
  • Replaced leaky glued hard pipe between the pump and filter with new hard pipe and union fittings.
  • Scooped and vacuumed out a thick layer of leaf and algae muck
  • Brushed regularly
  • Taken out the railings and ladders to be scrubbed separately
  • Brought the chemistry to:
    • Alkalinity: 50ppm
    • pH: 7.2
    • Calcium: 275ppm (probably will level out above 300ppm after my final addition today.)
    • CYA: 50ppm
    • Chlorine: shocking 1x/day to 20ppm with cal hypo, losing about 5ppm per day now. No CC registering at the moment. We're about to use up our 50lb bucket.
Our assumption, up until now, was that the pool was too dirty to start a real SLAM.

Now, the pool water is blue, but quite hazy. We'll switch to bleach one the cal hypo runs out, and start a SLAM. I'm hoping that the haze will dissipate both from clearing out any algae and stopping cal hypo use.

Is there anything else we should be doing?
Click to expand...
What type of filter do you have? Are you monitoring the increase in filter pressure? You should backwash when pressure is 25% above the starting (clean) filter pressure. Have you backwashed it?
You should be testing and adding chlorine every 4-5 hrs to maintain it at 20ppm FC. That will help clear.
 
HermanTX said:
What type of filter do you have? Are you monitoring the increase in filter pressure? You should backwash when pressure is 25% above the starting (clean) filter pressure. Have you backwashed it?
You should be testing and adding chlorine every 4-5 hrs to maintain it at 20ppm FC. That will help clear.
Click to expand...
It's a sand filter, and we've been clogging it like mad clearing out the algae and sediment. We've probably backwashed 30 times. The pool has finally cleared to the point where we only need to backwash every 2-3 days.

And yes, we'll be starting a SLAM shortly. Until now, with the amount of solids we were pulling out of the water, it seemed wasteful to try to maintain SLAM levels.
 
Can you tell us if the pool is vinyl, fiberglass or plaster?
How about a full set of test results from your own test kit-
FC
CC
ph
TA
CH
CYA
Salt if applicable

This info really helps us "see" your pool and determine our advice. Thanks.

Maddie :flower:
 
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Ok, you may be "shocking" it but knowing that algae reproduces pretty fast that's why we use the SLAM process. It isn't just one time treatment per day, and we use Liquid Chlorine because any puck will also contain either unwanted/unneeded calcium, or more CYA which will require *more* FC to compensate. We try to encourage doing a FC test at least 3-4x / day and adding the addition LC as your FC drops below SLAM Level. Test just the FC and CC while SLAMMING.

Here is the chart: (Note the SLAM level is on FAR RIGHT SIDE OF COLUMNS)
CYA (Stabilizer)Minimum FCTarget FCSLAM

SLAMing is the process of raising your FC high and maintaining it there to kill algae and break down any CC that may have formed. “Shock” is highly misused word, often used for a variety of purposes related to the same goals as SLAMing. SLAMing is something you do to your pool, not a special product that you use. Any unstabilized chlorine is suitable for use in SLAMing.
" style="color: rgb(30, 115, 190) !important; border-bottom-width: 1px !important; border-bottom-style: dotted !important; border-bottom-color: rgb(30, 115, 190) !important;">SLAM FC
20*23-510
3024-612
4035-716
5046-820
6057-924
70*58-1028
80*69-1131
90*710-1235
100*811-1339
 
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YippeeSkippy said:
Ok, you may be "shocking" it but knowing that algae reproduces pretty fast that's why we use the SLAM process. It isn't just one time treatment per day, and we use Liquid Chlorine because any puck will also contain either unwanted/unneeded calcium, or more CYA which will require *more* FC to compensate. We try to encourage doing a FC test at least 3-4x / day and adding the addition LC as your FC drops below SLAM Level. Test just the FC and CC while SLAMMING.

Here is the chart: (Note the SLAM level is on FAR RIGHT SIDE OF COLUMNS)
CYA (Stabilizer)Minimum FCTarget FCSLAM

SLAMing is the process of raising your FC high and maintaining it there to kill algae and break down any CC that may have formed. “Shock” is highly misused word, often used for a variety of purposes related to the same goals as SLAMing. SLAMing is something you do to your pool, not a special product that you use. Any unstabilized chlorine is suitable for use in SLAMing.
" style="color: rgb(30, 115, 190) !important; border-bottom-width: 1px !important; border-bottom-style: dotted !important; border-bottom-color: rgb(30, 115, 190) !important;">SLAM FC
20*23-510
3024-612
4035-716
5046-820
6057-924
70*58-1028
80*69-1131
90*710-1235
100*811-1339
Click to expand...
"Chlorine: shocking 1x/day to 20ppm with cal hypo, losing about 5ppm per day now. No CC registering at the moment. We're about to use up our 50lb bucket. Our assumption, up until now, was that the pool was too dirty to start a real SLAM. Now, the pool water is blue, but quite hazy. We'll switch to bleach one the cal hypo runs out, and start a SLAM."

"And yes, we'll be starting a SLAM shortly. Until now, with the amount of solids we were pulling out of the water, it seemed wasteful to try to maintain SLAM levels."

Yes, now that we've finished removing fifty or a hundred gallons of rotting leaves, as I said, a SLAM is next. Or at this point, ongoing.

"Is there anything else we should be doing?"
 
We prefer liquid chlorine (10-12%) over bleach (3-6%) as bleach is weaker and they've put in so many additives that you don't want in the pool water, unless you can find fresh PLAIN bleach and understand it will require more (ounce for ounce) than liquid chlorine. In years gone by bleach was ideal then...it also used to be cheap and easy to find.

Brush daily, make sure nothing solid remains at the bottom and SLAM away! :testkit:
 
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