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Thread: Do I really need higher CH?

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    Do I really need higher CH?

    I am a pool virgin setting up a virgin pool. Water has been in a couple of weeks and I have been using the forums and the Pool Calculator to educate myself and work on getting the water chemistry as it should be. A big thank you to all who contribute to these resources.

    Pool is an infinity lap pool with a 65' edge and a SWG, about 20,000 gallons. It is fully tiled with 1" tiles, so lots of grout. It is outside and in full sun (most days) from about 10.00 am to sunset. I have no access to pool chemicals locally (hence 0 CYA at this time), so I have been using only Clorox and muriatic acid so far. I am ordering a shipment of pool chemicals and will follow Pool Calculator recommendations re CYA once they arrive in 2-3 weeks time. Will probably also add Borax at some point. Currently running VS3050 on speed 2, 24/7, chlorinator at 50% in daylight hours, and adding about 1.5 quarts bleach every night. As there is no CYA, chlorine is usually less than 1 by morning and does not register later in the day, but pool is staying clear and sparkling so far.

    My question concerns the calcium level I should be targeting. Current numbers are:

    ph 7.6
    TA 90
    CH 110
    Salt 3

    Everywhere seems to suggest I should be aiming for a CH level of at least 250, but after playing with the numbers in the Pool Calculator (PC) I am wondering if this is really right for me. The SWG and the need to circulate the trough water over the long infinity edge from time to time to keep the trough sanitized are going to result in high PH levels as I understand it, and I am thinking it likely that it will be easier to operate with a target PH of 7.8 or even 8. With a PH of 8 and the numbers above, the PC gives me a CSI of 0.19 ('Balanced'). Raising the CH to 250 changes the CSI to 0.5 ('Potential to become scaling'), so why might I want to raise the CH? My understanding is that the higher CH is to protect the plaster (in my case grout), but if the CSI remains within the OK range then surely that is not a concern? It seems to me that leaving the CH where it is gives me more leeway on a high PH....?

    Once the chemicals arrive, I am thinking CYA 70, TA 60, CH ??, and PH where it settles, as long as the CSI is within range. Obviously I will have to add muriatic from time to time, but I am seeking to minimize acid use. I would welcome comments.

    If any of the gurus on the site would like me to run any experiments on a pool with truly 0 CYA then let me know. I am currently using a Taylor 2005 test kit so accuracy of measurements of chlorine levels is currently limited by color matching, but I plan to bring in a 2006 test kit with the chemicals.
    21,500-gallon tiled gunite with 65' infinity edge. Two Intelliflo VS pumps, one for trough one on pool. Pentair 520 cartridge filter on main circuit ,Pentair 200 cartridge filter on edge circuit. Easytouch, Intellichlor 60, Intellichem with external acid pump, Intellibrite 5g lights.

    Testing: Taylor K2006 (with FAS/DPD). Taylor K1766 salt.

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    Mod Squad Bama Rambler's Avatar
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    Re: Do I really need higher CH?

    Welcome to TFP.

    A couple of questions if you don't mind.
    Where are you located?
    & how did you get a salt level of 3?

    I think you need to bring your CH up a little if you have a lot of grout but 200 would probably be good. With an swcg you're going to want your TA to be a little lower so that'll help a little.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: Do I really need higher CH?

    Quote Originally Posted by Bama Rambler
    Welcome to TFP.

    A couple of questions if you don't mind.
    Where are you located?
    & how did you get a salt level of 3?

    I think you need to bring your CH up a little if you have a lot of grout but 200 would probably be good. With an swcg you're going to want your TA to be a little lower so that'll help a little.
    Thank you very much for your quick reply. Sorry - that should be Salt 3000 ppm

    Actually, I see now that when the PC page reloads it drops the '000' from my previously input 3000 for salt; the default reload has 3 in the salt box, presumably in the expectation that users' salt level will begin with a 3 (3xxx ppm). While I saw the 3 previously, I incorrectly assumed that the box was simply showing the value in thousands, i.e., 3 = 3000 ppm. Of course, running the PC with the correct value of 3000 changes the outcome. Thank you!
    21,500-gallon tiled gunite with 65' infinity edge. Two Intelliflo VS pumps, one for trough one on pool. Pentair 520 cartridge filter on main circuit ,Pentair 200 cartridge filter on edge circuit. Easytouch, Intellichlor 60, Intellichem with external acid pump, Intellibrite 5g lights.

    Testing: Taylor K2006 (with FAS/DPD). Taylor K1766 salt.

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    37,879

    Re: Do I really need higher CH?

    Grout is just like plaster as far as calcium goes, so follow the recommendations for plaster pools.

    You probably don't want to focus on CSI so much. Concentrating on CSI leads to micro managing, which tends to use extra chemicals that you could otherwise avoid using. CSI can vary quite a bit and everything will still be fine. Just keep all your levels in the recommended ranges and you will be fine.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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