what happened to my TA

[rd3500]

How long is the return line from your SWG back to the closest outlet?

I would say it is pretty long. The first outlet is in the middle of the pool, no outlets on the side where the equipment is.

Does the actual chlorine production of your cell match your expectation?

still trying to figure it out, right now it is set at 66% running for 8 am to 2 pm. I will adjust the next few days, might be good at that setting. The swg is for up to 40k gallons, my pool it is 13k, maybe even 10-11k (it took much less salt to get it to spec so maybe number of gallons is lower than what I think).

How much MA have you added since installing the SWG and how did your TA react to that?

1.5 gallons of 14.25%. I did not check TA before adding the SWG unfortunately.

I assume that pH tracking comes from an automated system? With automated MA dosing?

yes, comes from the atlas pool kit. No automated dosing yet, I am doing the dosing manually. Ok on testing manually, I can use the kit I have.

Just had another idea. If you have a fixed pH probe in your plumbing, where exactly is it? Before or after the SWG?

the probe right now is in the skimmer. I have a spot for it in the plumbing before the SWG.

@JamesW, the MA I am using is 14.25% (the one from lowes, sorry I did not specify it before), fill water is at 130. You still have a valid point I think, I regret not measuring the TA before installing the SWG.

 

[JamesW]

6 gallons of 14.5% will drop the TA by about 125 ppm.

 

[mgtfp]

Based on James' calc, the TA drop seems to make sense. But that pH rise is still a bit of a mystery. Is your FC currently rising like crazy? If you were overproducing chlorine (i.e. producing more than gets used by UV and critters load) by like 10 or 12 ppm per day, that pH-rise from 7.5 to 8 in one day could make sense, maybe a bit less when accounting for CO2 outgassing that happens in parallel.

I think all you can do now is to keep monitoring pH, TA, FC, and the daily SWG chlorine production, MA and fill water additions, for a while. And then we can try to make some sense of it.

 

[Orion7319]

yes, comes from the atlas pool kit. No automated dosing yet, I am doing the dosing manually. Ok on testing manually, I can use the kit I have.

Your relying on testing from a probe? Is this the one your using? It sounds like it’s way out of calibration to me. When was the last time you checked ph manually?

Wi-Fi Pool Kit | Atlas Scientific

The Wi-Fi Pool Kit reads pH, ORP, and temperature. All readings are automatically temperature compensated and uploaded to ThingSpeak.

atlas-scientific.com

 

[rd3500]

@Orion7319, yes I have the atlas pool kit with the industrial probe. I just tested it manually with the k2006 kit:

FC: 7
PH: 7.2

7.2 is very different from the 7.8 the probe is showing. I ordered the calibration solutions.

Maybe I kept the PH very low for a while and that contributed to the reduction of TA. I'll know more once I get the solutions and I can recalibrate the probe. Thanks a lot.

 

[mknauss]

Great catch Orion!

 

[Orion7319]

@Orion7319, yes I have the atlas pool kit with the industrial probe. I just tested it manually with the k2006 kit:

FC: 7
PH: 7.2

7.2 is very different from the 7.8 the probe is showing. I ordered the calibration solutions.

Maybe I kept the PH very low for a while and that contributed to the reduction of TA. I'll know more once I get the solutions and I can recalibrate the probe. Thanks a lot.

I’m glad you got it figured out! Also I learned something new because of this thread that will probably help me out as well….

 

[Orion7319]

Great catch Orion!

 

[mgtfp]

Wow, didn't expect the probe to be that far off. Now it makes sense. Instead of rising from 7.5 tiy 8, that was probably between below 7 to somewhere in the low 7s, which would explain the rapid rise even once you forced TA that far down.

What I still don't understand is the faster rise after switching from liquid chlorine to SWG, because with decreasing TA the rise should still rather slow down than speed up. Unless it was only recently that your probe went out of calibration.

You mentioned that your probe is in the skimmer. Have you recently added any chemicals via the skimmer? CYA e.g. is known for fouling probes.

 

[rd3500]

Great catch Orion!

agreed!!

Have you recently added any chemicals via the skimmer?

no, but there is something I did that might have made a difference. I removed the probe for a few days while I was installing the SWG and just put it in a glass with tap water. It stayed there for about 10 days, not ideal.

Maybe that ruined the calibration of the probe and when I put it back in, I started to lower PH a lot more than needed.

I'll know more as soon as I can recalibrate the probe, in the meantime I'll let PH go back up to a healthier lever.

 

[mgtfp]

Maybe... I know that you certainly shouldn't store a pH probe in distilled water, and storing it in tap water is not recommended for a normal handheld meter (I store mine always in storage solution and it is never out more than 0.01-0.02 when I calibrate it). But yours is clearly designed to be "stored" in pool water. Maybe tap water is still to "clean" and messes with the internal buffer solution. If it has, than it might need refreshing in storage solution before recalibration. Does the manual say anything about it?

 

[rd3500]

Maybe tap water is still to "clean" and messes with the internal buffer solution. If it has, than it might need refreshing in storage solution before recalibration. Does the manual say anything about it?

sorry I missed this before, the manual does not say anything about it but the calibration was way off, so I'll monitor in the next few weeks with manual testing to see if the problem is resolved.

Here is an update.

The rate of ph increase dropped dramatically in the last couple of days.

I recalibrated the probe, as suggested it was way off (before calibration it was reading PH 7 solution as 7.84...).

I guess because the probe was giving artificially high readings, I dropped PH to a very low value (6.6 my guess) and it quickly went back up to 7.2 or so. And now it is slowly approaching 7.4, confirmed by manual testing and readings from the calibrated probe.

I will leave PH alone for a few days to see what it is going to do.

I did a full set of tests just now and here are the results:

FC 6.5
PH 7.35
TA 60
CH 480
CYA 50
Salt 3800

I also bought Boric Acid from Duda but I am waiting to balance the water before doing anything with it.

I guess I need to bring CYA to 70 adding this much stabilizer




and maybe the TA to 60?

I was somewhat surprised by CH at 480, last time I checked (6 months ago) it was at 350. I understand it goes up, I thought it would take longer. Should I do something about it now? I am asking because if I need to replace water, then I'll wait on the CYA and TA adjustments...

 

[mknauss]

I was somewhat surprised by CH at 480, last time I checked (6 months ago) it was at 350. I understand it goes up, I thought it would take longer. Should I do something about it now? I am asking because if I need to replace water, then I'll wait on the CYA and TA adjustments...

Your fill water CH is 250 ppm. Each year, you will evaporate close to two pool volumes. So it will go up by 500 ppm per year, give or take. You can slow that by using a solar cover, especially in the spring and fall. Or you can use softened water for make up water due to evaporation.

You can survive this summer with the water you have. Just track CSI. Will have to maintain a lower TA and manage pH.

 

[Orion7319]

sorry I missed this before, the manual does not say anything about it but the calibration was way off, so I'll monitor in the next few weeks with manual testing to see if the problem is resolved.

Here is an update.

The rate of ph increase dropped dramatically in the last couple of days.

I recalibrated the probe, as suggested it was way off (before calibration it was reading PH 7 solution as 7.84...).

I guess because the probe was giving artificially high readings, I dropped PH to a very low value (6.6 my guess) and it quickly went back up to 7.2 or so. And now it is slowly approaching 7.4, confirmed by manual testing and readings from the calibrated probe.

I will leave PH alone for a few days to see what it is going to do.

I did a full set of tests just now and here are the results:

FC 6.5
PH 7.35
TA 60
CH 480
CYA 50
Salt 3800

I also bought Boric Acid from Duda but I am waiting to balance the water before doing anything with it.

I guess I need to bring CYA to 70 adding this much stabilizer

View attachment 411005


and maybe the TA to 60?

I was somewhat surprised by CH at 480, last time I checked (6 months ago) it was at 350. I understand it goes up, I thought it would take longer. Should I do something about it now? I am asking because if I need to replace water, then I'll wait on the CYA and TA adjustments...

My experience with TA and PH, is that with limited aeration and a TA of 60 the PH will want to stabilize around 7.8 or so. I don’t have any fancy water features, I have a vinyl pool and my fill waters CH is 50, so balancing TA and CH to maintain a certain CSI isn’t much of a factor me. Don’t take my statement as advice for what you need to do, it’s just my observation on where the PH will want to land with a TA of 60.

 

[rd3500]

You can survive this summer with the water you have. Just track CSI. Will have to maintain a lower TA and manage pH.

that's my current situation and my goal situation:



for the CSI, I could swear I remember between - 0.3 and +0.3 but I see on the calculator between -0.6 and 0.6.

PH will want to stabilize around 7.8

that would be fine with me too.

 

[mknauss]

Looks fine. Your TA will rise as you add fill water. Manage pH.

Your pool water will warm substantially in the next two weeks. That raises CSI too.

 

[JamesW]

What is the current temperature and how high will it get?

 

[rd3500]

thanks @mknauss.

What is the current temperature and how high will it get?

72f current temperature. I have never tracked it before so I don't know how high it will go, @mknauss probably know as he is reasonably close to where I am.

 

[mknauss]

It will top out at 90-95F. Depending on sun exposure in the afternoon.

Our pool water is at 85F or so as we cover the pool in the spring to keep it warm enough to swim.

 

[rd3500]

here is an update and brief recap: my ph was going up real fast after installing the SWG. Turned out the issue was the probe was out of calibration. After calibrating, PH went up from 7.3 on may 16th to 7.8 today may 28.

Situation now:

FC 4.5
PH 7.8
CYA 55-60
TA 60
CH was 480 last time I check which was 12 days ago.

Is it ok at this point (given that the PH problem has been sorted) to add borates? Maybe raising CYA to 70 first?