Updated: Post AA treatment, Chlorine demand struggle

[mucoy]

About to do AA treatment after opening pool but looking for advice on water chemistry before. Current numbers:
Pool is 29K gallons, IG Plaster.
FCH: 0.5
pH: 7.7
TA: 70
CH: 200
CYA: 20 (will raise after AA treatment )
Salt: 3400 (ready to turn-on the salt cell but haven't yet)
Water Temp: 64
CSI: -0.44

I have been allowing my CH to stay on lower side because the pool suffered from extreme pH creep and I had a bad experience with scale buildup during winterization about 7 years ago. I've since found that leveling out my TA around 70ish reduces the creep quite a bit.

Pool math suggests that lowering pH to 7.2 for the AA treatment will result in a pretty low and corrosive CSI at current water temps. Do I need to raise CH before doing the treatment?

 

[ajw22]

Pool math suggests that lowering pH to 7.2 for the AA treatment will result in a pretty low and corrosive CSI at current water temps. Do I need to raise CH before doing the treatment?

Any plaster damage from aggressive water with a low CSI takes weeks if not months to occur. A short time for treatment will not cause any issues.

Ascorbic Acid Treatment - Further Reading

www.troublefreepool.com

 

[mucoy]

Thx, upon reflection I think It’s time to increase CH anyhow so will do that first.

 

[mucoy]

OK did the AA treatment. Before I did,
45 lbs Calcium Saturday. Water test results as below except CH now up to 380.

+24 hours (Sunday) 4lbs Ascorbic acid followed by 4qts Proteam Metal Out. Stains ~75% gone.
Pump run without filter media for 3 hours.
Cleaned and replaced filter cartridges.

Monday pH below 7.0, added 1/2 gallon liquid chlorine followed an hour later with 4lbs. baking soda.

Sheer descent waterfall active to airate water to help bring up pH.

Brushed pool. Water turned cloudy!? Will run filter and see if it is still cloudy tomorrow morning, but not sure what caused the cloudiness. Is it from baking soda and aerating at same time? Anybody have thoughts?

 

[ajw22]

• Baking Soda = big TA change, small pH change
• Borax = Big pH change, small TA change
• Soda Ash/Washing Soda = big pH change, big TA change.

Raising your TA with your high CH caused the pH to suddenly rise and the calcium to come out of solution and cloud up. It should clear up in a while.

 

[mucoy]

Thanks for the info! TA went down to 40 so needed to raise that as well but didn’t notice the effect on pH rise was so small with the baking soda. I’ll test in the morning and switch to soda ash if I still need to raise both significantly.

I need to keep TA around 70 to control massive pH creep. If I need to keep pH at 7.2 to avoid stains coming back and with 70 TA, thought I should raise CH a bit to avoid corrosive CSI. Was targeting 350 CH but overshot a little.

 

[mucoy]

Did AA treatment 5 days ago, still can't keep chlorine in the pool.
Have been through 6 gallons 12.5% liquid chlorine plus 5lbs of 47% trichlor disolved in bucket and dispersed in water. (Note: I switched to Trichlor temporarily because I ran out of liquid chlorine and it was available. Plus still bringing up the CYA and thought it couldn't hurt that the added chlorine was stabilized).

Current status:
pH - 7.0-7.2
CH - 360
CYA - 40
TA - 70
Salt - 3600
water temp 70

• 10 pm last night added 1 lb dissolved Trichlor. At 11 pm FC was 1.2 ppm, CC was 0. Turned on the IC40 at 60% in attempt to supplement chlorine overnight and possibly outpace the pool demand.
• 9 am this morning Chlorine was 0. Added another 1 lb. dissolved Trichlor. SWG still on @ 60%.
• 12 pm FC - 0, CC - 0. Added another 1 lb. dissolved Trichlor. SWG still on @ 60%.
• 1 pm FC- 0.4, CC - 0. Added another 1 lb. of dissolved Trichlor. SWG still on @ 60%.
• 2 pm FC - 0 to 0.2; CC - 0. Added another 1 lb. of dissolved Trichlor. SWG still on @ 60%.

Will head back to pool store for more liquid chlorine as soon as I have time to break away from day job .

What gives? Do I have an invisible algae bloom lurking that the added chlorine levels are not enough to wipe out? I did added 32 oz of polyquat before starting the process 5 days ago. Filters and skimmer baskets are clean. I ended up using ~6 lbs of AA overall. Stains were not lifting very quickly so maybe got a little heavy handed over a several hour period . However, think I have added more than enough chlorine by now to burn out the 6 lbs AA in 29K gallons?

Any recommendations? Concerned that I will eventually get algae, have to SLAM and unwind everything I did .