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Thread: New owner with high CH, planning on doing a partial drain/fill after stain treatment

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    New owner with high CH, planning on doing a partial drain/fill after stain treatment

    Hello,

    First, I want to say thanks for the wealth of knowledge available here. This post may get long, but in an effort to provide the full picture, here is what I have:

    We recently purchased the home we have been renting over the last year that has a 9 year old 9500gal IG exposed aggregate pool with attached spill over spa, treated with liquid chlorine and uses cartridge filter. The previous owners contracted with a local service to maintain it weekly while we rented and the pool has always been clear, but I have decided to take this over since purchasing.

    I recently came across the BBB method just doing some general pool research and was hooked on the simplicity of it. I purchased a TF100 kit and have been monitoring the pool over the last couple weeks while the pool service continued to maintain it before we purchased. Most readings have been ok, but the pool service has been slamming the pool very hard each week, with FC readings of 20+ the day after service. FC does come down as expected over time, but usually only gets to ideal ranges by the time they return and do it all over again.

    FC=16-20+ after service
    CC=0
    ph=7.4
    CYA=40
    TA=100
    CH=750
    TDS=3400
    Borates=0-10

    The biggest issue has been growing reddish brown stains across the bottom and sides of the pool which I suspected was iron precipitating down from the ridiculous amount of liquid chlorine they've been using.
    First goal was to get what I could in normal ranges

    My current maintenance levels:
    FC=5
    ph=7.4
    CYA=40
    TA=80
    CH=750

    I added in boric acid purchased from dudadiesel($30 for 25lbs) to get borates up to 50ppm only because it was cheap and seems like it has a lot of benefits and would help prevent algae during the stain treatment.

    With the info here, I then dropped FC to 0.5, ph to 7.1. I did an Vit C test and after verifying stain removal success. Yesterday I added in the recommended dose of polyquat 60. I then spread in 1 lb of AA powder also sourced from dudadiesel. The stains were 75% gone within an hour. I followed that up with 1 quart of Bioguard's Pool Magnet Plus (HEDP) and dropped in a CuLator 4.0 pack into the skimmer and ran the filter overnight. As of this morning the stains are completely gone and it looks like a brand new pool. Filter is still running.


    At this point the only potential issue in the pool is the calcium hardness is fairly high at 750ppm. I brought a sample to a local store just to verify my results. They also measured my TDS at 3400. I see some scaling (not a lot) on a few of the tiles around the surface of the pool.

    I suspect the pool can still be easily managed with elevated CH, but I'm strongly considering doing a partial drain and refill now to get the CH lower and also remove some of the now suspended metals my AA/HEDP treatment has lifted off the surface so I don't have to keep adding HEDP as frequently.

    To avoid risk or damage to the pool pump I was just going to rent a 52gpm submersible pump with large hose from home depot for ~$40. The local family owned pool store who supplied with PQ60 and HEDP are actually pretty good and knowledgeable. They did recommend trying and getting the CH levels down with a refill. They also suggested to turn the pool pump off for a day or longer to let a lot of the solids settle to the bottom and then do the pump out, hopefully evacuating a higher percentage of the tds/metals/etc. The house is on the water and although it is raised quite a bit from added earth, I will only drain 1/3 or maybe a bit more at a time, to keep the pool safe and then refill. Probably do this 2 times, maybe 3.

    My fill water is city sourced and has a base CH of ~125, so unfortunately it will probably take a good bit of water replacement to get the CH down.

    Am I wasting my time/effort or does this seem reasonable to move forward with doing a partial drain/refill to reduce CH?
    Does turning the pump off for a day to let solids settle to the bottom sound reasonable or is this risky/have no benefit?
    And last but not least, its only been 24 hours since the stain treatment the write ups here are usually recommending to wait 48 hours and bring FC and PH very slowly after. Should I wait longer to replace water or just have at it since the stains are gone.

    Thanks!
    9500 gal IG exposed aggregate pool w/ build-in spa, Hayward cartridge filter, TF100 kit

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    Texas Splash's Avatar
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    Re: New owner with high CH, planning on doing a partial drain/fill after stain treatm

    Hello and welcome to TFP! Sounds like you've done some homework and having the TF-100 was a great move. As to your concerns:
    - I wouldn't worry about the TDS. We don't get wrapped-up in TDS as a TFP pool with no algae isn't concerned about algae-supporting material.
    - Your CH is elevated, but can be countered by keeping the pH and TA low which is actually good for you. A lower pH (7.2-7.4) helps to manage iron better.
    - If you chose to exchange water to lower CH, remember that adding new water with CH will put most of it right back. For example, if you lower CH to 300, with a couple partial refills it could be back to 500 or so quickly. You might find better success timing your water refills in the rainy season. It's not uncommon for FL residents have a hard time maintaining CYA and CH because of all the rain and pool drains.
    - Leaving the pump off to let iron settle may not work as expected. The HEDP and other products you've added should keep that stuff "bound" and prevent it from precipitating out. A water exchange would help but only if the new water is again (like the CH above) free from iron, otherwise you'll just be adding metal right back. If you have a water softener, you might be able to do slow/partial refills a little at a time to help between the rainy season.

    I think your biggest issue right now is containing the metals (iron) which you've done quite well so far. Keep the pH low, and (yes), increase FC slowly to your target area and watch how the water reacts. Along with the low pH, keep the TA on the lower end as well (60 or so) to help counter the elevated CH you have. Refer to the "CSI" row on the Poolmath calculator from time-to-time to ensure your CSI readings is in an acceptable range.

    Hope that helps.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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  3. Back To Top    #3

    Join Date
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    Re: New owner with high CH, planning on doing a partial drain/fill after stain treatm

    Thanks for your reply and advice Texas.

    I turned the pump off for about 6 hours last night and things got cloudy fast with visible sediment floating around (it had been about 30 hours since the stain treatment)! Turned the pump/filter back on before bed and all is clear again this morning. I've been monitoring the PSI on the filter and it only went up 2 psi overnight - I was concerned it might spike.

    I'm going to try out exchanging some water and see how it goes. I'll have to add some more boric acid back in as well when I'm done, but that's not a big issue. I ordered the reagents for drop testing borates this week...the lamotte test strips I bought were awful and basically unreadable.

    I will keep TA and PH on the low side from here out. Will report back on how everything goes and if the CH goes down to a reasonable level.

    Thanks again!

    [edited - source fill water still 125]
    9500 gal IG exposed aggregate pool w/ build-in spa, Hayward cartridge filter, TF100 kit

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    duraleigh's Avatar
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    Re: New owner with high CH, planning on doing a partial drain/fill after stain treatm

    Do you have any idea how CH got so high? Very unusual for florida.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  5. Back To Top    #5

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    Re: New owner with high CH, planning on doing a partial drain/fill after stain treatm

    The previous renters before we moved in "maintained" the pool themselves and it was a cloudy mess when we first looked at the house a year ago. The actual owners were very meticulous with the home and decided that was enough and they just just had a pool service handle it while we were renting. It's anyone's guess as to how it got to be so high, but chatting with the pool shop here they said maybe the previous people loaded it up with cal-hypo or something along those lines. Maybe ph was out of whack and leached out of the surface? They were surprised how high it was as well, but they said they see it from time to time in the area.
    9500 gal IG exposed aggregate pool w/ build-in spa, Hayward cartridge filter, TF100 kit

  6. Back To Top    #6

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    Re: New owner with high CH, planning on doing a partial drain/fill after stain treatm

    An interesting update:

    I drained approximately 3200 gallons from the pool and refilled based on the water meter readings earlier this afternoon.

    Out of pure curiosity and thinking it couldn't hurt, I ended up buying a 5 micron high flow KDF+Carbon RV water filter from a local walmart that goes right on the end of the hose (https://www.walmart.com/ip/Camco-EVO...ilter/23636871). I really suspected I was tossing money away on this thing as it will do nothing for calcium(which I verified with a CH test on the output before and after), but they claim this thing filters all sorts of metals, sediments and other impurities. Despite the mixed reviews there and on Amazon, it works fine and didn't leak or have any issues.

    Well I ran municipal water through this thing for the last 5 hours during my fill. It cut water output just over 2x (3 gpm output vs 7gpm unfiltered)... it would have taken a full day to refill at this rate, so not expecting much anyways, I also had two unfiltered hoses also filling to speed things up. After shutting everything off, I opened up the canister filter to find this:

    Attachment 53777

    Yikes...I knew there was some iron in the water, but this looks pretty bad. That filter was bright white before starting. I could rub off globs of red goop off the thing. Now I wish I didn't run the two unfiltered hoses!


    Back to the CH results...I took a surface sample from about 6 inches in water came back with a CH of 450. I decided to see whats going on at the bottom so I got in with a clean sealed bottle and went to the bottom of the deep end(6ft) and opened it to fill a sample there. There was an obvious warmer thermocline around 3.5 feet down. Sample came back at full strength with CH of 750. Going to run the rented pump again and do another partial drain out.

    Next fill I will just be using filtered water despite the increased time it will take. I can't find out how many gallons the filters are rated for, I suspect ~1000-1500 based on similar products. I scrubbed what I could off and will probably get a replacement filter for it tomorrow to finish the fill.

    Hopefully this testing adds some value here. I will follow up with final results when this is all done.
    9500 gal IG exposed aggregate pool w/ build-in spa, Hayward cartridge filter, TF100 kit

  7. Back To Top    #7

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    Re: New owner with high CH, planning on doing a partial drain/fill after stain treatm

    Refill work and re-balancing are completed.

    Final results
    Replaced 7300 gallons based on meter readings.

    As of this morning, readings are:
    FC=12
    CC=1
    pH=7.3
    TA=60
    CH=325
    CYA=30
    Borates=~25

    The pool gets hit with sun pretty hard most of the day, so I will keep an eye on the FC drop off and maybe increase the CYA in 3 days once things settle in a little more. Ordered more BA and will get that back up to 50 once it's in.
    9500 gal IG exposed aggregate pool w/ build-in spa, Hayward cartridge filter, TF100 kit

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