Quick Aeration/Lowering TA Questions

[tucsontico]

I'm currently raising my CH to the recommended range. I want to lower my TA next. Will aeration via my SWG be enough to bring the pH back up after I dose it down to 7.0-7.2 with MA? If so, about how long should I run the SWG to get the pH back up? Will my in-floor cleaner add much to the aeration since it does roil up the water surface a bit. BTW, I do not have a spray bar or a fountain to provide extra aeration.

Today's K-2006 test results:

FC-3
CC-0
pH-7.8-8.0 (takes 3 drops of acid demand reagent to drop it to 7.6)
TA-125
CH-180
CYA-60
Salt-3200
Temp- 72º F

Thanks for your help!

 

[JasonLion]

The SWG alone will work, but it will take a while, probably days, to raise the PH. Can you aim a return up so it breaks the surface?

 

[tucsontico]

Thanks! Should I run the SWG 24/7 until the pH comes back to normal?

I have flush-mount eyeballs and they do not rotate very easily. I will attempt to rotate the 2 returns in the shallow end to break the surface, but I'm not hopeful they'll create much of a stream.

One more question:
Reference the acid demand test in the K-2006 kit: Does each drop of acid reagent equate to a 0.1 pH drop? For example, if my water sample shows "about" 7.8 on the pH color chart and I put in 3 drops of acid demand reagent to get it to exactly match 7.4 pH color, can I assume that my water sample's pH was originally 7.7?

 

[Richard320]

Why are you messing with TA? Your current numbers place CSI at 0.15, which is great. If salt is at 3000, it goes to -0.08, which is also just fine. Why mess with it? Just lowering pH with acid will lower TA through normal maintenance.

And as for adding CH, I imagine that the fill water and normal evaporation in Arizona should take care of that soon enough.

 

[JasonLion]

There is no point in running the SWG 24/7, that will use up the cell life, which isn't worth it.

The simplest thing you could do would be to switch to lowering the PH to 7.2, instead of 7.5 each time you do lower it.

Drops in the acid demand test don't have anything to do with what they PH is or how much the PH changes. You count drops to see how much chemical you need to add to change the PH as much as it changes. Say the PH reads 7.8, and you want to lower the PH to 7.2, you add drops until the PH gets to 7.2, then look up that number of drops in a table to see how much acid to add to get the PH down to 7.2. You can do the same thing with PoolMath in most cases. However the acid demand test is more precise for large PH changes and works even if the starting PH is out of range of the PH test.

 

[Richard320]

One more question:
Reference the acid demand test in the K-2006 kit: Does each drop of acid reagent equate to a 0.1 pH drop? For example, if my water sample shows "about" 7.8 on the pH color chart and I put in 3 drops of acid demand reagent to get it to exactly match 7.4 pH color, can I assume that my water sample's pH was originally 7.7?

No. They tell you the amount of acid you need to add. You look it up in the manual and find your pool's volume and it tells you how much acid to get to 7.4. It's much easier to just skip the acid demand test and plug your numbers into PoolMath. You should get pretty much the same answer.

 

[tucsontico]

Why are you messing with TA? Your current numbers place CSI at 0.15, which is great. If salt is at 3000, it goes to -0.08, which is also just fine. Why mess with it? Just lowering pH with acid will lower TA through normal maintenance.

And as for adding CH, I imagine that the fill water and normal evaporation in Arizona should take care of that soon enough.

I was advised in this thread http://www.troublefreepool.com/threads/73295-Replaced-the-Pool-Frog-with-an-IC40-SWG to bring the CH up and drop the TA down. I am currently adjusting my pool water balance as advised.

BTW, I had to drain 2/3 of my water this spring due to excessively high CYA (120+). My fill water, seems to be "softer" this year than last year (when the pool was initially filled) with a CH of 150.

 

[jblizzle]

Well, it is not a cut and dry answer. IF you are going to lower the TA, then you should raise the CH so the CSI does not get too low. Or, you could just leave things as they are and keep the pH a little higher to maintain a reasonable CSI.

FYI, I replaced most of my water March 2013 and my CH was 130ppm, one year later it is 280ppm just through evaporation and top-off water. I figure I can go about 2 more years before I will have to consider replacing water again to get the CH back down. If I had added CH last year, then it would appear I would have to drain and refill every 2 years.

EDIT: I might see if I can harvest some of the water run-off from my roof during monsoons to see it I can keep the CH rise a little slower.

 

[tucsontico]

There is no point in running the SWG 24/7, that will use up the cell life, which isn't worth it.

The simplest thing you could do would be to switch to lowering the PH to 7.2, instead of 7.5 each time you do lower it.

Drops in the acid demand test don't have anything to do with what they PH is or how much the PH changes. You count drops to see how much chemical you need to add to change the PH as much as it changes. Say the PH reads 7.8, and you want to lower the PH to 7.2, you add drops until the PH gets to 7.2, then look up that number of drops in a table to see how much acid to add to get the PH down to 7.2. You can do the same thing with PoolMath in most cases. However the acid demand test is more precise for large PH changes and works even if the starting PH is out of range of the PH test.

Thanks. I understand the Taylor tables for the acid demand and I do use the PoolMath calc to double check my water balance. I was just curious if the number of drops might somehow equate to the pH color chart to more accurately tell what your pH really is. I'm probably trying too hard to get the chemistry exact!

 

[tucsontico]

Well, it is not a cut and dry answer. IF you are going to lower the TA, then you should raise the CH so the CSI does not get too low. Or, you could just leave things as they are and keep the pH a little higher to maintain a reasonable CSI.

FYI, I replaced most of my water March 2013 and my CH was 130ppm, one year later it is 280ppm just through evaporation and top-off water. I figure I can go about 2 more years before I will have to consider replacing water again to get the CH back down. If I had added CH last year, then it would appear I would have to drain and refill every 2 years.

EDIT: I might see if I can harvest some of the water run-off from my roof during monsoons to see it I can keep the CH rise a little slower.

Well, I've already added 14 lbs of calcium chloride to raise the CH about 80 ppm (per the PoolCalc). So, I guess I'm committed to bringing the TA down now as well. I was following advice from this thread: http://www.troublefreepool.com/threads/73295-Replaced-the-Pool-Frog-with-an-IC40-SWG.

BTW, I have a rainwater harvest barrel (865 gal) for my drip irrigation system. A decent approximation of how much water runs off your roof is: 1000 sq ft of roof and 1 inch of rain equals nearly 1000 gallons. My barrel filled in two small monsoon storms last summer.