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Thread: Correct levels for plaster pebble/shale SWG pool.---

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    Correct levels for plaster pebble/shale SWG pool.---

    ---with concrete base.? For an expert.Here is the info. requested so I can get an acceptable correct answer to my ?'s- 16,000gal.,cart. fil.CL580 Jandy, In Ground,plaster-pebble/shale over concrete base,established pool over 1 yr. old.My ? is I have read all your info.on P.S.& your levels to keep water chemistry balanced for my type pool are different from Taylor Aqua chem & my Jandy owners manuel.I'm leaning to trusting your info. due to the fact that your not selling chemical & you seem to be experts & base your figures on expert analysis.I have printed out your baseline #'s for recommended levels for a swg pool but it doesnt take into account for pool surface type. Does that matter? Also the TA info. I have says level should be 80-120 & you say 60-80 & no lower than 60.I also understand the relationship of TA -ph.What is my perfect level for my pool & what are the other perfect levels for ph ,FC, CYA,CHardness if different from your posted chart for my pool? TIA!!! Rob

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    Re: Correct levels for plaster pebble/shale SWG pool.---

    Welcome to TFP!

    Did you see Recommended Levels in the Pool School? It lists the three main types of pool surfaces which are vinyl, plaster and fiberglass. Plaster, concrete, grout (in between tile), pebblesheen, etc. are all like plaster in terms of requiring a saturation of calcium carbonate to protect these surfaces. The recommendations DO account for pool surface type as you'll notice different CH recommendations for different types (high CH isn't needed in vinyl pools, for example).

    Our 60-80 ppm TA is for pools with a saltwater chlorine generator. A higher TA isn't a problem if your pH doesn't tend to rise and if your other water parameters are such that the saturation index isn't high so you don't get scaling. Usually though, a TA of around 70 ppm often works for most SWG plaster pools. If you have aeration sources such as spillovers, waterfalls, fountains, etc., then you may need a lower TA to prevent the pH from rising.

    You can use The Pool Calculator to calculate the Calcite Saturation Index which should be near zero though for SWG pools it's usually targeted to be slightly negative (around -0.2) to help prevent scaling in the SWG cell.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Correct levels for plaster pebble/shale SWG pool.---

    Yes saw your rec. levels@ pool school & H20 balance for SWG's info. Was wondering why Jandy owners man. & other info. Ive read says TA 80-120 but P.S. info. says 60-80 with 70 perfect? & TA & ph very important to keep @ 70 & 7.5-7.6 but no lower? TIA! Rob

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    Re: Correct levels for plaster pebble/shale SWG pool.---

    Also the CYA level for my plaster pool is 50-60 too low for it & I need to keep it higher @ 70-80? Thanks Rob

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    Re: Correct levels for plaster pebble/shale SWG pool.---

    The levels you see here are "recommended". However, if you have to use different levels to staisfy the installer to maintain warranty, then you have to take that into consideration.

    I am not sure I exactly understand the questions in the last 2 posts.
    Jason, TFP Moderator
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    Re: Correct levels for plaster pebble/shale SWG pool.---

    The reason for the lower TA level and the higher pH target is to reduce the rate of carbon dioxide outgassing that causes the pH to rise. This chart shows how much pools are over-carbonated. A lower TA and higher pH has less carbon dioxide in the water so it outgasses more slowly and that has the pH rise more slowly. With a TA of 70 ppm, pH of 7.7, CYA of 80 ppm, the TA you use in the chart would be around 50 (due to the higher CYA than the 30 ppm assumed in the chart) so you'd be at 1.8 which means that there is 2.8x times as much carbon dioxide in the water as there would be if in equilibrium with the air. So the rate of carbon dioxide outgassing is substantially reduced.

    The higher CYA assumes your pool is exposed to sunlight. The higher CYA, even with proportionately higher FC, loses less chlorine to the UV in sunlight and that lets you turn down your SWG on-time and that has the SWG generate fewer hydrogen gas bubbles so less aeration of the water and it's also less undissolved chlorine gas outgassing as well. All of this reduces the rate of pH rise.

    pH rise is a common problem with SWG pools. If your pool isn't experiencing that, then having the lower TA, higher pH target, and higher CYA wouldn't be needed (though the higher CYA also helps extend SWG life).
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Correct levels for plaster pebble/shale SWG pool.---

    Thanks TFP Expert for the info. & help! Let me see if I have a basic understanding & summerize what you are telling me.TA should be @ 60-80 (70) & ph @ no lower than 7.5 (7.6-7.8)range to acct. for ph drift/rise which I do have problems with my ph doing this in my SWG pool & CYA level should be kept @ a higher level of 70-80 to help with FC chlorine degredation due to sunlight & other factors which I also experience problems with here in the summertime? Thanks! Rob

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    Re: Correct levels for plaster pebble/shale SWG pool.---

    Yes, your understanding is correct. By the way, "TFP Expert" is the title, but the username is "chem geek".
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Correct levels for plaster pebble/shale SWG pool.---

    Thanks for all your tech.help & expertise & taking the time explaining the info. so I could comprehend it!!! Thanks Again Special TFP Expert Chem Geek!!! Rob

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