Testing noob - a few questions

[wgipe]

Hi! Our new pool has been filled and circulating for a week or so now. Waiting on the cover to be installed next week so we can heat it. In the meantime, I've been working to get he water where it should be. You guys have helped me so much to get to this point - the list of mistakes I *would* have made were it not for this site is long.

So....I've got a few questions pertaining to testing below. My PoolMath logs are linked if that helps.

Today's test results:

FC 7.5
CC 0.5
pH 7.8
TA 70
CH 250
CYA 60
Temp 56F
CSI -0.45

My questions are as follows:

1. Should I be concerned with the CC? That went from 0 - 0.5 a few days ago, then back to 0, then to 0.5 again today. From what I read, this is normal - correct?
2. I added calcium to get to 250 because of the heater/IC40 requirement of 200-400. Assume I can let that as it is, as the fill water will no doubt cause that to rise?
3. Ideal salt level in the IC40 manual is 3200, but the cell itself says 3600. I took it to 3600 - is that okay?
4. How high should I let pH drift before I correct? Then what pH should I shoot for when I add MA?
5. My FC is running high according to the chart, which shows a target of 4. This is because I turned on my SWCG and it got a little carried away before I realized I had to turn it WAY back to 10%. Should I just let that drift down with the sun (if we ever see it again here in Ohio)?
6. CYA test. This one has me scratching my head a little. I've done the stand with back to sun, vial at waist, etc. method consistently. I've added what should be enough to bring me to 80, but I'm still at 60 - and I might be pushing it to say the dot is gone at 60. I've added a few pounds of CYA with no noticeable difference. There was a very consistent relationship between adding CYA and seeing it in the test a few days later up to 50, and it seems it takes a TON of CYA to take the next jump. I know that test is a logarithmic scale - does that explain why it takes more to make a jump later in the scale, or would the inverse relationship be expected? Are the testing scale and effect of CYA addition not related at all?

In case it helps to know, my fill water is from a well and tested as follows:
CH 125
TA 70
pH 7.8
FC/CC 0

I have not added any fill water, as we've not had a lot of sun and have had a couple inches of rain, so it's kept steady at the skimmer overflow level.

Sorry for the long post - just wanted to make sure there was sufficient detail so as not to waste anyone's time.

Thanks in advance for your continued advice!

Wes

 

[mknauss]

1. 0.5 CC is normal. No issue
2. No more calcium needed. To be honest, you did not need that much. The IC40 would be better off with 0 CH. The heater, well, they really do not need any but the manufacturers use steam boiler data to say they do. Your pool heater is not a steam boiler.
3. Salt is fine. I keep mine at 3000 ppm. As long as the SWCG is happy.
4. 8
5. FC is fine. Higher is better than too low. One flock of birds could consume the extra in a heartbeat.
6. If you added the CYA, it is in there. Until you have splash out or over flow. Your pool volume may be off some. In your climate, leave it. Test it in a month or if you have a significant overflow event.

 

[wgipe]

1. 0.5 CC is normal. No issue
2. No more calcium needed. To be honest, you did not need that much. The IC40 would be better off with 0 CH. The heater, well, they really do not need any but the manufacturers use steam boiler data to say they do. Your pool heater is not a steam boiler.
3. Salt is fine. I keep mine at 3000 ppm. As long as the SWCG is happy.
4. 8
5. FC is fine. Higher is better than too low. One flock of birds could consume the extra in a heartbeat.
6. If you added the CYA, it is in there. Until you have splash out or over flow. Your pool volume may be off some. In your climate, leave it. Test it in a month or if you have a significant overflow event.

Thank you! I’ll keep an eye on things on the CYA front and let that CH dilute if possible with rain. I sure appreciate the advice.

 

[jseyfert3]

Just adding a few comments to @mknauss amazingly succinct post...I wish I could write posts like that.

Should I be concerned with the CC? That went from 0 - 0.5 a few days ago, then back to 0, then to 0.5 again today. From what I read, this is normal - correct?

If using the 10 mL sample size (which you should for TFP levels), 0.5 is your lowest resolution. So even if you have 0.2, it'll show up as 0.5. So don't sweat it.

Then what pH should I shoot for when I add MA?

Generally 7.6 is recommended unless you have a specific reason to keep it lower. Like battling a very high CSI from calcium buildup, which is highly unlikely to be a problem in the midwest with all our rain and partial pool drains each winter.

In case it helps to know, my fill water is from a well and tested as follows:
CH 200
TA 270
pH 7.8
FC/CC 0

When I scrolled back through your logs, I see a note 22 days ago that says "fill water" followed by a test of TA 70 and CH 125?

 

[wgipe]

When I scrolled back through your logs, I see a note 22 days ago that says "fill water" followed by a test of TA 70 and CH 125?

Mercy sakes. That’s correct. I need to wake up. Good catch. I’ll edit above.

Thanks, also, for the other details!

 

[jseyfert3]

No worries. I was going to say with a fill TA of 270 you'd have some pH rise after every time you did a pool top-up from the well water. But a TA of 70 out of the tap is amazing, that's just about perfect. You'll need very little acid to manage your pool.

My fill water can be as high as 400 ppm TA (deep wells in my city).

 

[Turbo1Ton]

The one thing I didn't see anyone mention for your CYA is that the water sample temperature should be room temperature or higher. Your pool water temps have been mostly in the 50's and 60's according to your logs, and if you are immediately testing after sampling, that could lead to errors in the rest result. Bring the sample inside and let it stabilize, or run your sample bottle under some warm water to bring the temp up. I made that same mistake as well.

--Jeff

 

[wgipe]

One more question on this topic.... My pH has tested almost completely stable at 7.8 for the past 2-3 weeks. I was expecting it to rise with the use of the SWCG, and the one time I took pH down to 7.2, it came back up over time and stabilized back at 7.8. It's been so stable that I'm wondering if my eyes are not seeing things correctly. Is that normal, or should I somehow verify my test is accurate?

 

[jseyfert3]

pH rise is slower at higher pH levels, to the point of being almost non-existent at your TA level. It is not your eyes. Don’t try to force it low and enjoy your steady pH!

(that of course does not mean to stop testing pH, just to stop being worried about it not climbing)

 

[wgipe]

Awesome. Thanks for confirming!