How soon should I retest?

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thunderkyss

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Jul 24, 2010
172
Pt. Arthur, TX
Let's say my Ph is off the chart. Greater than 8. I added 2 gallons of muriatic acid this morning, around 11:00 am.

I just retested, my Ph is still showing to be greater than 8. I also did the Acid demand test, 19 drops.

I'm thinking something is not right.

I dumped another gallon of muriatic acid.

Was I wrong to think something should have happened in the last 10 hours? Am I a little too zealous with my K-2006? Should I have waited until tomorrow?
 
Yes, the high TA and aeration will cause the pH to increase quite a bit. Also, it's likely that you have scale all over the plaster and some of the acid that you are adding is being used up dissolving the scale.

Run the pump on high 24/7, brush the pool at least once a day and keep adding acid until you get the pH and TA down. Keep the filter clean. Dilute the acid 10 to 1 with water to speed up distribution. Brush after adding acid and retest in 2 hours. Always add acid to water, do not add water to acid.
 
thunderkyss said:
I also did the Acid demand test, 19 drops.

I'm thinking something is not right.
Click to expand...
Yikes! Unless the sulfuric acid in the acid demand test went bad, and that's pretty unlikely, 19 drops would imply a LOT of acid needed to lower the pH. Every drop represents 9.16 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons and would lower the TA by 3.6 ppm. 19 drops would lower the TA by 68.1 ppm and makes no sense from a pH perspective since the pH would have to be 10.7 to end up at 7.5 which seems implausible. On the other hand, it could be a TA of 400 ppm and a pH of 9.0. Did you test your TA? You should do that.

Aeration won't get the pH above 8.5 at TA of 100 or above 9.0 at a TA of 400. The carbon dioxide outgassing at most TA levels will stop completely around that pH. So for the pH to get even higher would require addition of some sort of base such as pH Up.

So definitely test your TA and if it is indeed 400 ppm then your pH could be 9.0, but as James points out, you would probably have a lot of scaling and/or cloudy water if the TA and pH are that high.
 
thunderkyss said:
My pool builder sent out a repair man to check my heater. He says it's got calcium scale in it.

My most recent numbers are
FC: 3 ppm
CYA: 60 ppm
TA: 200
ph: 8+
ch: 270

The heater was in service for about 4 weeks, I don't understand how it can already be scaling.
cavitation-when-my-heater-starts-t30011.html
Click to expand...

I think that this is a new plaster pool and the calcium hydroxide is contributing to the pH rise.
 
OK, I just retested, vacuumed my pool, & cleaned my filter, strainer, and pump strainer. My most recent numbers are
FC: 2.8
CC: 0.2
CYA: didn't check, last reading (yesterday) 55
TA: 130 (pool store checked yesterday said 200)
PH: 8+
CH: didn't check, last reading (yesterday) 270 (pool store also yesterday 450)
AD: 11 drops

So, my TA is coming down, the AD is coming down.

In the last week, I've added 4 gallons of full strength muriatic acid and I've seen my TA come down from 250 to 170, or 80 (ppm?)

Pool calculator says I should have a goal of 70-90. I'm shooting for 70, because I want to get my CSI down very low. Though I don't see any scaling in the pool or hot tub, I've been told my heater isn't working because of scaling in the heater.

So with a goal of 70, is it reasonable to believe I'll need to add another 3-4 gallons of muriatic acid in the next couple of days? The pool store closes on Sunday, & I want to make sure I get enough.
 
chem geek said:
thunderkyss said:
I also did the Acid demand test, 19 drops.

I'm thinking something is not right.
Click to expand...
Yikes! Unless the sulfuric acid in the acid demand test went bad, and that's pretty unlikely, 19 drops would imply a LOT of acid needed to lower the pH. Every drop represents 9.16 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 10,000 gallons and would lower the TA by 3.6 ppm. 19 drops would lower the TA by 68.1 ppm and makes no sense from a pH perspective since the pH would have to be 10.7 to end up at 7.5 which seems implausible. On the other hand, it could be a TA of 400 ppm and a pH of 9.0. Did you test your TA? You should do that.

Aeration won't get the pH above 8.5 at TA of 100 or above 9.0 at a TA of 400. The carbon dioxide outgassing at most TA levels will stop completely around that pH. So for the pH to get even higher would require addition of some sort of base such as pH Up.

So definitely test your TA and if it is indeed 400 ppm then your pH could be 9.0, but as James points out, you would probably have a lot of scaling and/or cloudy water if the TA and pH are that high.
Click to expand...

My K-2006 only goes up to 8, the color is quite a bit darker than 8, but I'm just saying 8+, or 9 knowing it's way out of wack. My most recent TA test shows 130.
 
JamesW said:
I think that this is a new plaster pool and the calcium hydroxide is contributing to the pH rise.
Click to expand...

That may be the case, it is a new plaster pool.

I also have 5 return jets, all of them are pointed towards the surface, causing ripples in the water. I've got a raised spa, with 4 aerating jets, and a spill over causing a water fall effect.

Should I redirect the 5 pool return jets so they do not break the surface?
 

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By the way, when the pump isn't running, the water is very, very clear. I can see the bottom (7.6 ft) with much clarity & detail.

I was reading the pool school, and realized with a new plaster pool, I should be brushing the sides & vacuuming daily, which I haven't been doing. I have been letting the Polaris 9300 sport run at least twice daily though. Is that good enough, or should I manually brush & vacuum daily for a little while?
 
manually brush and vacume daily too for a little while and yes, you want as little aeration as possible right now so do redirect the returns if you can. Just keep on top of the Ph testing/acid additions and you should be ok.
 
JamesW said:
I think that this is a new plaster pool and the calcium hydroxide is contributing to the pH rise.
Click to expand...


Could this also explain a CH number of 270? My original test with my K-2006 was

FC: 3.4
CYA: <30
TA: 50
PH: 8+
CH: 160

CH went from 160 to 279 in about 4 weeks. I was using Tri-Chlor to for chlorination for 2 weeks, then switched to chlorine. That, I'm sure, explains the rise in CYA.
 
Still reading through the Pool School.

Still learning.

Figure I should tell you my pool has borates in it. I don't know how much, Monday I'll see if they sell something at my pool store to check it. But I know for sure my pool builder added sodium tetraborate to the pool .
 
Fresh plaster raises PH, TA, and CH levels very rapidly for the first three or four weeks, and then more slowly for up to a year. You need to keep up with the acid demand, which can be very significant. Some people are adding a gallon a day for a while. You may need to use more than that for a short time to catch up.
 
Latest numbers.

FC: 4.2
CC: 0.0
TA: 110
Ph: 7.6
AD: 7 drops

I think I should add, that for the AD test I'm using a goal of 7.0 until a few minutes ago, I didn't know any better. So all my AD numbers have been for a desired ph of 7.0 (which of course, I don't want) so the actual AD is not as bad as my numbers suggest. I decided to continue to test AD with a goal of zero for the moment, so the numbers would at least be relative. But to drop from 7.6 to 7.4 took 3 drops, just so you know.
 
JasonLion said:
Fresh plaster raises PH, TA, and CH levels very rapidly for the first three or four weeks, and then more slowly for up to a year. You need to keep up with the acid demand, which can be very significant. Some people are adding a gallon a day for a while. You may need to use more than that for a short time to catch up.
Click to expand...


Good to know.

In the last four days, I've dumped 6 gallons of muriatic acid in the pool.
 
Whoops.

I added another gallon of muriatic acid to the pool. I wanted to get my CSI below 0.6, so I was shooting for a low TA.

with my current numbers, my CSI is already 0.16 according to the pool calc. It was 1.3 with my previous readings. I guess the lower Ph affected the chemistry more than I thought.
 

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