First TF100 Test - Next steps and targets?

[peterdaly]

Finally got around to getting a good test kit.

FC 16
ph 7.5
TA 110
CH 175
CYA 33

SWG with Auto Pilot. I have read the suggestions here for SWG chemistry. I believe salt is around 3000ppm, but don't have an accurate test (yet.)

I added 6lb of stabalizer to socks in the skimmer last night with a target of 75 for CYA. I understand that is expected to take a week to show up.

I also already lowered my pH to 7.1 last night wit muriatic acid (confirmed with test this morning) and started aeration...as pool math and pool pal requested ph of 7.0-7.2 to lower TA.

A few questions:
1. Yes, I know FC is high. I was surprised. Shall I ignore that for the next week until CYA is up? It was also at the end of a no sun day with the (blue) cover never removed.
2. I don't fully understand the pH/TA relationship. Will aeration lower my TA and increase my pH, or is lowering pH part of lowering TA? How long should aeration take to lower TA? Hours/days/weeks? I turned the two returns up to break the water surface.
3. Should 80 be my TA target, since that's the point of overlap between AutoPilot recommendations and TFP SWG target?

I think my targets should be:
FC 4-5? AutoPilot wants 1-3. I want a TFP ;-)
pH 7.5
TA 80
CH [don't care a lot, as long as it's not super low or super high]
CYA 75
Borates - sounds interesting, but I figure I should get everything else in balance first.

Reasonable targets? Am I on the right track? Suggestions? Course correction?

As always, thanks. You guys rock.

 

[GreatCanadian]

Test your chlorine as you normally would. Just let it fall into the recommended range for your CYA level. Worthy to note is that you can't rely on your pH reading with that high chlorine level (high CL level can give false high pH reading). Wait for it to fall below 10 before testing your pH again.

Don't worry too much right now about your TA. Don't target a specific number. The main purpose of a lower TA is to keep your pH from rising too fast. Your pool just might like the TA where it is. If your pH does rise, you will be bringing it down with MA anyway, which will lower your TA. If pH doesn't rise, your TA is fine. My neighbor's pool has a TA level of 110, and her pH is locked on 7.5, so she doesn't bother to lower TA at all.

For your question number 2, aeration does not lower the TA. The addition of the MA lowers the pH AND the TA. Aeration brings your pH back up without increasing the TA level. Repeating this process eventually lowers your TA to where you want it. But as I said, I wouldn't target a specific number. Lower your pH when it rises, and eventually your TA will find the sweet spot. My sweet spot is at 70. Yours may or may not be 70.

Ignore the Autopilot recommendation of CL level 1-3. It doesn't take into account your CYA.

Good idea to wait on the borates til everything else is balanced.

Your CYA target of 75 is good. Your CL target of 4 to 5 is cutting it close with CYA 75. If you could manage to NEVER let it get below 4 great, but if you're targeting 5, then that's only a 1 ppm drop. If, for example, you are losing 3 ppm per day, I would target 8, so that it never drops below 5. Check the Chlorine/CYA chart. Good luck, looks like you have a good grasp on this.

 

[peterdaly]

GreatCanadian,

Water Balance for SWGs:
http://www.troublefreepool.com/content/138-water-balance-for-swg-saltwater-chlorine-generator

To summarize:
FC 3-5 ppm
CYA 70-80

The SWG water balance page here suggests FC 3-5 ppm, which is why I stated my targets where I did, and is exactly why I am asking here.

I do see that the CYA chart on this site suggests higher.

CYA 70 Target FC 5
CYA 80 Target FC 6

Should the FC on the salt water balance page be revised/raised?

 

[Richard320]

A few questions:
1. Yes, I know FC is high. I was surprised. Shall I ignore that for the next week until CYA is up? It was also at the end of a no sun day with the (blue) cover never removed.

No, CYA will protect it even more, so it will get too high and start irritating skin and bleaching swimsuits. Turn the SWG down. Or even off until FC falls a bit.

2. I don't fully understand the pH/TA relationship. Will aeration lower my TA and increase my pH, or is lowering pH part of lowering TA? How long should aeration take to lower TA? Hours/days/weeks? I turned the two returns up to break the water surface.

Acid lowers pH and TA. Aeration raises pH but does nothing to TA. High TA pushes pH up. That being said, if you scroll down on poolmath to Effects of Adding Chemicals, you can see how much TA should drop when you add acid to lower pH. TA in itself isn't harmful. I wouldn't go out of my way to aggressively lower it if I were you. The returns pointed up will help speed along the pH rise, but just adjusting pH regularly will get TA down.

3. Should 80 be my TA target, since that's the point of overlap between AutoPilot recommendations and TFP SWG target?

I think my targets should be:
FC 4-5? AutoPilot wants 1-3. I want a TFP ;-)
pH 7.5
TA 80
CH [don't care a lot, as long as it's not super low or super high]
CYA 75
Borates - sounds interesting, but I figure I should get everything else in balance first.

Reasonable targets? Am I on the right track? Suggestions? Course correction?

As always, thanks. You guys rock.

80 is fine. Really, the target is more for calculating how much baking soda to add if you need to raise TA, not how urgently you need to lower TA. It really doesn't matter if it's 70 or 100. In time, your pool will settle into its sweet spot where the pH needs hardly any adjustment. Wherever that is, leave it alone and enjoy the thing.

 

[R.J.]

FWIW, I run my salt pool at FC 6-8 and a CYA of 70. Water looks and feels great. When the FC gets to 5 the water looks a little "dull", so to speak. Yours might be different. Experiment a little and see what works best for your pool.

 

[jmbradwell]

I also run my SWG with a goal of having 6ppm at the end of the day when it shuts off. When it gets to 5ppm, I increase the SWG output 10%. When it hits 7 ppm, I decrease it 10 %. Daily loss varies by how much sun you are getting. Sunny hot days = more loss. Cloudy days = less loss. It is all a balancing act.

Good luck.

 

[GreatCanadian]

The reason I stated 5 to 8 was to give you a bit of wiggle room. As you can see from the above posts, these guys do the same thing, targeting 6 to 8 or thereabouts. The chart states minimum of 3, target 5. I try to stay at or above the target. I do not want to see it drop to 3. You do not need do worry about the harshness of the chlorine if your level is 6 or 7 because your CYA protects from that. Also you stated that you are targeting CYA of 75, which I would treat as 80. The target for that is 6 ppm chlorine. If you attempt to stay between 3 and 5, you have no wiggle room and are taking a risk. Just my opinion.