Opening Numbers and Well Water

[nocaster]

Hello,

I use my well to fill and top off my pool. Our ground water here is very hard and alkaline. The wells numbers are:

pH 6.2
CH 560
TA 430

My pool numbers are currently:

pH 7.8
TA 290
CL 1 ppm
FC ??? (new reagents on the way)
CYA much less than 30.


I added about 20" of water last week to get the level up into the skimmer. At that time the pH was about 6.2 but within a week has moved to 7.8. Did I see a rapid change because my TA is high? With fill water at TA 430 and I always going to be fighting to keep the TA lower?

I've always used OTO test kits before and have never attempted to keep everything balance. I have a fiberglass pool and I don't know how much I should worry about the CH. Any advice would be much appreciated.

 

[duraleigh]

Nocaster,

Your water issues are w-a-a-y above my pay grade. How your numbers could've moved in that manner I can't imagine. Others will be along soon that will give you some meaningful advice. I'll be very interested in the outcome.

Welcome to the forum.

 

[JasonLion]

When your TA is very high and your PH is low, CO2 will out gas raising the PH. Actually this is happening all the time but the higher the TA and lower the PH the faster it happens. If you have water features that aerate the pool it will happen more quickly.

CH numbers that high could cause scaling problems, particularly at high PH and high TA. You will need to keep a close eye on your PH and make sure it doesn't go too high or you will probably have scaling.

 

[nocaster]

Is this out gassing something I can see? When my light is on at night I can see many small bubbles in the water. I don't see them break the surface like a glass of champaign, but they seem to be suspended in the water. Should I add muriatic acid to bring the pH up at this point?

It's been a long time since chemistry class. Does a higher number indicate lower pH?

 

[The Mermaid Queen]

Can't answer your other questions, but muriatic acid brings your pH DOWN!

 

[chem geek]

A higher pH number indicates more basic/alkaline while a lower pH number is more acidic. As for seeing bubbles, it is unlikely you saw the carbon dioxide outgassing -- it's possible, but I think unlikely. Do you, by any chance, have a saltwater chlorine generator (SWG)? If so, then if it was running when you saw the bubbles, then the bubbles are likely to be hydrogen gas bubbles from the SWG (which is normal).

Your numbers indicate that your pool is way over-saturated with calcium carbonate (the saturation index is +1.0) so your water may get cloudy or precipitate scale. You need to get your TA lower by using the Lowering Your Alkalinity procedure found here. Lower the TA to at least 100 if not 80. When you are done lowering the TA, have a target pH of around 7.5. You may still fight some pH rise, but with your very high Calcium Hardness you won't have that much choice, but at a lower TA level the situation should be better for you.

 

[nocaster]

Thanks chem geek. I don't have a SWG but I do have a return that works like a spa jet when the eyelet is removed. I'll let that run for some time and get the TA down. I'll report back what happens.

This place is full of sage advice not found in pool stores!