FC, PH and how often to add acid

[Hkdman]

Hello! I have a couple of quick questions:

1. Last night at around 6pm, I took a chlorine reading and my FC was 5.8. This morning at 8am I checked and the chlorine is 5.6. Is that a normal amount of chlorine loss overnight? Temp was around 78 or so.

2. My ph yesterday was a little high at 7.8 so I added acid to bring to optimal of 7.6. I checked at 8am and the ph is back to 7.8. Should ph fluctuate that much? Should I add acid everyday to bring it to 7.6? How often would you add acid? 7.8 is within the acceptable range so should I wait until ph reads around 8 before adding?

Thanks!

 

[cwswifty]

Was any additional FC added overnight? If not, .2 FC loss overnight is well within the 1 ppm loss that would indicate an algae problem. If you SWCG was on you should probably turn it up.

It is not uncommon for a plaster pool to want to hover in the high 7’s. It rises more quickly when the pH is lower. My current regime is to add MA at a pH of 8.2 and bring it down to 7.6. That keeps me in a CSI range of -0.3 to + 0.2.

 

[newdude]

my FC was 5.8.

Switch to 10ml samples. The .2 resolution is simply not needed and you'll save 2.5X the supplies. Each drop is .5 FC.

A 2.X sucks across all CYA levels
A 8.X is awesome across most CYA levels

The 2 or the 8 is critical and the point X is of no concern.

little high at 7.8 so I added acid to bring to optimal of 7.6.

All 7s are equally ok. There is no 'more ok' than 'regular ok'. Dose at 8+ and only to a high 7.

As the TA comes down, (which it will do as you manage the PH) it will help slow the PH rise.

 

[Hkdman]

Hi! No - the SWG was not on last night. I am currently running the pump from 8AM-6PM. Based on that, is .2 loss acceptable?

 

[newdude]

.2 loss acceptable?

With a +/- 1 drop variance, 1 drop is effectively 0 in TFP land. An overnight loss up to 1 FC is considered ok for normal pool operation. You're golden.

 

[Hkdman]

Newdude - so are you recommending that I increase FC to 8? I know that is within the acceptable range…but I was kind of thinking that somewhere around 6 or 6.5 would be perfect…no? Good point on 10ml sample - I will switch to that.

 

[cwswifty]

FC/CYA Levels

 

[newdude]

so are you recommending that I increase FC to 8?

I was making a point about the 25 ml sample testing to 8.8 (?) instead of 8.5 with 10ml.

The .8 or .5 are meaningless IMO. The 8. is the important part of the story.

was kind of thinking that somewhere around 6 or 6.5 would be perfect…no?

Up to you. The closer you run to minimum, the closer you have to watch it. One electronic hiccup, power blip or rain may shut your cell off for the day.

Without your cell producing during the day, you'll lose 4 or 5 ppm in the peak season, because Texas. A 6.5 is great when things go to plan, but it's too low for the times it doesn't IMO. 8 is the lowest I go, and I often go over target level, but we all have our comfort zone.

 

[.ben]

Texas summers are no joke. Not uncommon to have weeks of 100+ degree weather. My pool can easily lose 4.5 ppm of FC per day.

In summers, I try to maintain at least 8 FC with CYA of 80. Trying to target 6 is too close to the danger zone IMO and there is no discernible advantage to doing so.

There is no need to chase an “ideal” pH as each pool will settle on its own ideal. For me, this is 7.8. I wait until I read 8 or 8.2 before dropping to 7.6 or 7.8. I usually add MA about twice a week.

 

[Hkdman]

Great advice all. Thanks! I will raise it to 8. I am just a little nervous because I always hear the ideal is 1-4 which I know is not what tfp.advocates. that being said - i am.all in on the top method so I will increase to 8!

 

[newdude]

I always hear the ideal is 1-4

That's at sucky yucky pool dot com.

Try their ways at your own peril.

But for REAL. Your local to you member loses 4.5 fc per day in the heat. How the you gonna run a 1 to 4 ? There is no negative 3 FC, only 0. And Swampville, population : you.

 

[Hkdman]

Lol. Understood!

 

[proavia]

If you're on board with the TFP method, forget what you've heard elsewhere.
Most every other place is stuck in the 1980's.

The "perfect" FC target (if that even exists) is the one that NEVER allows your lowest FC to approach minimum for your CYA - 24/7/365. You can even run above FC 10 - just let FC fall to 10 or less to test pH.

 

[dfwnoob]

I'm very close to you and 3.5-4 FC is very normal loss for me during the summer. CYA on average hovers around 60. Because of the high average loss, I'm solidly on team run hot. I target 8, but it's not unusual for it to be 10 when I test it.

 

[Hkdman]

Makes sense! I am increasing it to 8. It should hit heck levels in another month. I'll increase it a little more at that time. Tks!

 

[Hkdman]

Question for the group. I just tested my chlorine using 10ml as recommended. Counted 11 drops so 5.5. I then wanted to check it against using 25ml and I counted 31 drops so 6.2. That is a .7 difference which seems a lot. Do you all experience the same level of discrepancy. I know people have said that the first number is really the one to watch versus the number after the decimal. But to me 5 is quite a bit different Than 6. Perhaps.i.am overthinking it?

 

[cwswifty]

Both tests have +\- 1 drop accuracy so there is some overlap. 5.5 could have been from 5 to 6 and 6.2 could have been 6 to 6.4.

 

[.ben]

There is no practical difference between an FC of 5 or 6. Just another reason not to live close to the minimum FC levels.

The key is to be consistent with your personal testing procedures.

 

[newdude]

Benefit of #teamrunhot number 273:

10ml says 10.5
25ml says 11.2
I say : 'Woohoo I'm nowhere near minimum'.

Have this discrepancy at 8+ and it really doesn't matter.

*I just turned my cell down before because I climbed to 12 and the next couple days will be overcast so I won't need any extra FC.

 

[Hkdman]

Hey! Yesterday, we had a rain storm that was probably as heavy a down pour as I have ever witnessed. Prior to the storm, my water was right below the overfill grate. When the rain was done, the water was about 3/4 of the way up the overflow grate and probably took a good hour for it to drain down to be below the grate. I live in Allen texas so perhaps some of my texas friends can vouch for me In any case, The night before, my FC was 8.5, ph was 8.0 (so I added 16 ounces of acid to bring it down to 7.6, and CYA was 80. This morning I checked and my FC was 7, PH was 8 again (so assume rose from about 7.6), and CYA was 60.

My question is whether or not chemicals change this much with heavy rainfall? Is that normal?