Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 4 of 4

Thread: First time pool drain, 22k IG plaster pool

  1. Back To Top    #1

    Join Date
    May 2014
    Location
    Bakersfield, CA
    Posts
    27

    First time pool drain, 22k IG plaster pool

    I don't want to get into the details, but someone else was watching my pool while I worked out of town this week, noticed my pool was cloudy and tried to be helpful by throwing a bunch of dichlor shock in earlier this week, didn't chlorinate again, and now that I'm back for the weekend my pool is green and my CYA is up from 50 to about 75...

    If there were sitcoms about TFPC pool owners, I imagine an episode would go like this week did.

    So anyways, now I'm draining about half my pool water. First time I've had to drain my pool, so a few quick questions:

    1. It's a plaster pool, and it's the evening. Do I have to change the water incrementally, or can I do it all in one go?

    2. Is there any drawback to using a submersible pump over my pool pump? I have a sump pump that I got for cheap at Harbor Freight, and it seems like it would be a better idea to put the wear on that rather than my pool pump. Besides, I can water the lawn and garden with the submersible and now feel like I'm wasting 10k gallons of water.

    3. Speaking of watering gardens, is there any issue watering with green water? I really don't want to waste the chlorine reshocking my pool at CYA levels this high. Half my garden gets watered by back flush run off once in awhile anyways, it's just seldom this green.

    4. The big question : how do I determine where to place the pump to get a 50% change? Since the pool depth goes from 3' to 8' it will look half empty far before it actually is half empty.

    5. Is there any truth to the statement "most CYA collects at the surface of the water, so draining from the top keeps you from having to change as much water."? I'd never heard it before, but it was in my newspaper last week and I found it while I researching whether or not there was a water change ban in effect in my city (there's not, and I was surprised to read about CYA in my local paper as obscure a subject as that is).

    Thanks!
    22k gal, IG Plaster, Hayward Pro Series Sand Filter (Mdl S244FT), Hayward Super II 1.5HP 2-Speed Pump (Mdl SP3010EEAZ), Hayward/Poolvergnuegen "The Pool Cleaner 2x" Suction Side Pool Vacuum, Build Date Unknown (Possibly 1969?)

  2. Back To Top    #2
    Scuba_Steve's Avatar
    Join Date
    May 2015
    Location
    Pooler, GA
    Posts
    311

    Re: First time pool drain, 22k IG plaster pool

    #4. Love random math equations! Assuming your pool went from 3-8 linearly with no flat spots at either depth then you would wait for your water to get to 3" on the shallow end. This is also assuming your pool is a rectangle.

    I made up dimensions of 27'x20', and these have no relevance on the result. I just needed dimensions that were close to 22k g. The parenthesis is the current depth on the shallow end and deep end. 27*12*20*12*((0.25+5.25)/2)*12/231=11108.57g of water remaining in pool.

    #5. Total myth
    6425g Intex Ultraframe 18'x48" AG
    Stock 1500gph cartridge filter / Intex SWG CG-28669 with E.C.O.
    Install date: 5/26/2015
    TF-100
    Helpful Links

  3. Back To Top    #3

    Join Date
    May 2014
    Location
    Bakersfield, CA
    Posts
    27

    Re: First time pool drain, 22k IG plaster pool

    Thanks! I thought #5 sounded fishy, given the fact I take my water samples far below the surface...

    - - - Updated - - -

    Free form pool with an inconsistent slope, I'm sad to say. I wish I knew the pump gpm and could do the math based on time. I may just drain to your suggestion anyways, top off tomorrow, and then retest CYA and do a second drain next weekend if it's determined I need to.
    22k gal, IG Plaster, Hayward Pro Series Sand Filter (Mdl S244FT), Hayward Super II 1.5HP 2-Speed Pump (Mdl SP3010EEAZ), Hayward/Poolvergnuegen "The Pool Cleaner 2x" Suction Side Pool Vacuum, Build Date Unknown (Possibly 1969?)

  4. Back To Top    #4
    Scuba_Steve's Avatar
    Join Date
    May 2015
    Location
    Pooler, GA
    Posts
    311

    Re: First time pool drain, 22k IG plaster pool

    Exact math aside, using the same equation if you went to 1' instead you would probably be a bit safer to not overshoot due to your inconsistencies in shape and slope. That would bring you to 14138g.
    6425g Intex Ultraframe 18'x48" AG
    Stock 1500gph cartridge filter / Intex SWG CG-28669 with E.C.O.
    Install date: 5/26/2015
    TF-100
    Helpful Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •