SWCG may be causing chemistry problems?

[Heavyhook]

I have aerating 24 hours round the clock form a strong jet from my filter return aimed at the surface. My tap water test are PH 8+, CH 10ppm, TA 260ppm. Our water is supplied from local wells. Our bedrock is limestone not far below the surface. At 7:30 am this morning water test were FC 3.5ppm, CC 0 ppm, PH 8.0 , Acid demand 5 drops to 7.6 ph, TA 100ppm, CH 60ppm, added 121 oz's 8.25% bleach.
My TA & CH are dropping as you anticipated. My scaling on the liner has been reduced by 75% so far. I have been adding 32 oz's of 31.45% Muriatic Acid daily. If I understand the Lowering Swimming Pool Alkalinity -- A Step by Step Guide correctly my PH needs to come down to 7.0 then be allowed to rise to its natural level. When should I start to see the PH drop? Do I need to increase the volume of Muriatic Acid daily since the TA has reached the target level of 100ppm to get the PH to drop now? Do I need to stop aerating ? Am I assuming right that I stay on bleach with SWCG off until all the water chemistry numbers are where we want them?
Also I looked back in my notes to 3 years ago when I changed the water in my pool. I had added 16 pounds of Calcium before I found the PoolForum and discovered it was not necessary with a vinyl liner pool!

[BigDave]

Since you have a SWCG, you might go a little lower with the TA.

Adding the Acid will bring the pH down directly (TA too). The aerating is to bring the pH up (without increasing TA) after reducing it with acid; when your pH and TA are where you want them, stop aerating.

You can always use bleach for chlorination. When you do resume operating the SWCG, pH will probably start to rise - use acid to keep it where you want it.

[Heavyhook]

Chem Geek recommended aerating and following directions from Pool Doc in "Lowering Swimming Pool Alkalinity -- A Step by Step Guide" which includes the following,


"If your CA / TA level is not what you need to be, then you keep adding acid, so the pH will stay down:
. . . so the lost carbonic acid will keep being replaced with newly converted carbonic acid
. . . so the CO2 will keep gassing off
. . . so the CA will keep dropping.

When your CA gets where you want it, just stop adding acid, but keep aerating till the pH returns to the 'normal' level.

Ben
PoolDoc"

My PH levels have never dropped during the time I have been reducing the TA and CH levels. This may be where I am getting off track. Pool Doc and Chem Geek say to keep aerating, and my understanding was that doing so during SWCG operation would help GAS OFF the CO2 created by the electrolysis process to help prevent the PH rising. Don't at some point I need to add enough acid to drop my PH to near the lowest level of my test kit recommended in "Lowering Swimming Pool Alkalinity -- A Step by Step Guide" ?

[kelemvor]

Yes, you need to be adding acid and testing pH often to keep the pH low while you aerate. Only when you're done do you need to let the pH rise back up.

The more often you can manage to test and adjust, the better it will likely go.

Something else worth mentioning. You can increase the CYA to 60ppm and reduce some of the chlorine loss due to sunlight. In Texas, it probably beats down just like it does for me here in FL. The circupool user guide recommends 30-60 CYA - I'd go 60. Also, the 7ppm fc is a little high of a target with a swcg. You really only need to be between 1-3. Lowering the output on your swcg to target this range will help keep pH climb in check too.

[BigDave]

Since you've reached your TA goal without ever getting the pH into the low end, finishing the TA reduction process will be a little different for your pool. Stop aerating and add acid until your pH is where you want it.

[Heavyhook]

Central Texas see's few clouds during the June 1st - 3rd week in September. With temps usually at 100 or above during that period the UV rays can be brutal. I had wondered about raising the CYA but hadn't ask, so thanks for touching on that! I think I can now grasp and follow your advice and understand the process better now. Thanks to all the support team members that came to my aid. This stuff can feel like a impossible task without your input!

[Pacecorp]

If you like, send us a water sample and we will call you with our thoughts. Mark the bottle with your name and phone number and send it to: [ Edit by admin - Address deleted ] This service is available to all of our customers. Thanks, Don


Don, you need to discuss this with me, before you post it here. What I'd expect to know is

1. What you are testing.
2. HOW (equipment / methods) you are testing.
3. What -- in outline -- you are recommending.

If I allow this to go ahead, I will probably require that test results and recommendations be posted HERE.