Ideal Calcium Hardness Level

joboo7777

Active member
Aug 8, 2020
40
McKinney, TX
Pool Size
15568
Surface
Plaster
Chlorine
Liquid Chlorine
Hello all,

First off I would like to thank you all for putting together quite the collection of knowledge for newbies like me to consume. I have a calcium hardness question that I hope someone can help me answer.

details of Pool
Gallons: 15568 (1k of which is a spa with spillover)
Stonescapes Aqua blue plaster
FC - 4
PH - 7.6
TA - 80
CYA - 55
CH - 430
Temp - 67
CSI - -.06
Tap water has 150 CH

I’m using 7.5% bleach and muriatic acid to Maintain FC and PH. I used Leslie Pools Hardenss Plus to raise CH from 160ppm to 430ppm and I’ve used Baking Soda to manage TA. My pool company does maintain the pool for free the first few months and believe they added cal hypo once in the past 4 weeks. I have since asked them to stop coming to maintain the pool as I will be taking over this responsibility using the TFP method.

The reason I brought CH to ~400 was because this was the ideal midpoint provided in the Pool Math app. I’ve since done some research on this and it seems that this may be too high? I understand it’s manageable and folks have way higher numbers. But why does Pool Math have an Ideal range of 350-550 when it seems that most forums posts on this site consider it too high?

thanks!
John
 

CrystalRiver

Well-known member
Jun 19, 2020
334
Massachusetts
Your CH level does not directly matter. CSI does. CSI is influenced by pH, water temps, alkalinity, CYA level, borates level, and CH. Keep your CSI between -0.3 and 0 and you're golden.

Over time, CH will rise as water evaporates and you refill with the hose. The calcium never leaves the pool except through draining or splash-out. Once the calcium builds to the point where managing the CSI is too difficult, then it's time to exchange some water to lower it.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome John! :wave: In hindsight, the ideal thing would've been to increase the CH a little (say ~ 350), and let the pH rise a little higher to about 7.8. PH is the quickest and easiest way to adjust CSI if the CH is too high or low. For now, your CSI of -0.6 is very nice due to the chilly water. If you ever get some significant winter or early spring rains, then you can lower the pool water a little and fill it up with fresh rain water to lower the CH. The PoolMath APP gives overall ranges and parameters, but as we learn the TFP recommended levels, we learn how best to adjust each item. If ever in doubt, just ask. Keep the link below saved as well. It's a great page with just about everything you need.

 

aussieta

Gold Supporter
TFP Guide
depends where in the world you live
florida gets a lot of rain so are always performing a water exchange whether they want to or not
elko nevada have very high ch in their fill water (410ppm) so ideally would start lower
my ch in tap water is 30 so i constantly need to add calcium
 

joboo7777

Active member
Aug 8, 2020
40
McKinney, TX
Pool Size
15568
Surface
Plaster
Chlorine
Liquid Chlorine
Thanks for all the responses. Although not ideal it sounds like 430 CH is ok for now. In Texas we get some pretty strong storms that can dump many inches of rain at a time. Realistically, how much of a reduction can I expect using rain water as fill?
 

JJ_Tex

Bronze Supporter
Jul 17, 2019
1,875
Prosper, TX (DFW)
Welcome neighbor. Your reduction is proportional to your drain and fill amount. For example, if you drain 10% and refill with rain then your calcium will decrease by 10%.

I personally would leave it for now and just manage your csi with ph adjustments. Your numbers now look awesome, just watch it when the temps change and of course no more cal-hypo.
 
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joboo7777

Active member
Aug 8, 2020
40
McKinney, TX
Pool Size
15568
Surface
Plaster
Chlorine
Liquid Chlorine
Welcome neighbor. Your reduction is proportional to your drain and fill amount. For example, if you drain 10% and refill with rain then your calcium will decrease by 10%.

I personally would leave it for now and just manage your csi with ph adjustments. Your numbers now look awesome, just watch it when the temps change and of course no more cal-hypo.
yea I think I’ll hold tight. But as you are also well aware, the rain gods in North East Texas can be brutal and it’s only a matter of time before we get 3-4 inches from a 20 minute storm..;)