Time to figure out pool water chemistry (and more)

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
43,235
Tallahassee, FL
Me? I would buy one just to have on hand. They come in mighty handy with a pool. Harbor Freight has them for under $100 bucks! That is what I have.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
12,851
Northern NJ
Any recommendations on purchase vs rent for a sub pump? Models you recommend?
I picked up this one at my local hardware store. You can probably find them for less cost on Amazon and other places.

It is helpful to have around the house.

 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,412
Laughlin, NV

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,412
Laughlin, NV
With that CH you will be replacing the water in your pool each year. I think your test is high. Testing CH at the higher levels truly requires a SpeedStir and following the Fading Endpoint test method. Read the Notes section of CH test directions
 

Diannapool22

Well-known member
Aug 14, 2018
58
Scottsdale, AZ
With that CH you will be replacing the water in your pool each year. I think your test is high. Testing CH at the higher levels truly requires a SpeedStir and following the Fading Endpoint test method. Read the Notes section of CH test directions
Ah interesting. Yes- the water definitely turned purple prior to going to blue. I probably added 5-7 more drops until the purple turned to more of a blue. I will try again with 5 drops R-0012 before adding anything else. I will order the SpeedStir today.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,412
Laughlin, NV
When you get your Speedstir, once you reach about 12 to 15 total drops of R0012, start 'bumping', or turning on and off, the Speedstir between drops. Also wait several seconds between drops. The color change can take time to develop.

I assume you used a 10 ml water sample and each drop to blue is 25 ppm CH.
 

Diannapool22

Well-known member
Aug 14, 2018
58
Scottsdale, AZ
When you get your Speedstir, once you reach about 12 to 15 total drops of R0012, start 'bumping', or turning on and off, the Speedstir between drops. Also wait several seconds between drops. The color change can take time to develop.

I assume you used a 10 ml water sample and each drop to blue is 25 ppm CH.
Yes 10 ml water sample. I will try again with Speedstir. Any concerns on high pH on the fill water?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,412
Laughlin, NV
The pH of Colorado River water is typically 8 or just above. So that is correct.

I would think your fill water is closer to 250 ppm CH, 130 ppm TA. That is what ours is and we live 1/4 mile from the Colorado River and that is what is delivered to our home.
 

Diannapool22

Well-known member
Aug 14, 2018
58
Scottsdale, AZ
The pH of Colorado River water is typically 8 or just above. So that is correct.

I would think your fill water is closer to 250 ppm CH, 130 ppm TA. That is what ours is and we live 1/4 mile from the Colorado River and that is what is delivered to our home.
Thanks! Speedstir arrives Friday. I am out of town Saturday so not sure when I will get to start draining/filling pool
 

Diannapool22

Well-known member
Aug 14, 2018
58
Scottsdale, AZ
Okay draining/filling the pool. Exit flow and entry flow seem about the same. How will I know when to stop? I don't have a way to measure the flow rate exiting/entering

Also got a Speedstir so going to test the water from right before fill just to see if I can get more accurate results.
 

Mendy48

Bronze Supporter
Apr 27, 2018
737
Midland, MI
If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end (through a skimmer or into a bucket on a step so you lessen the water disturbance) you can do a fairly efficient exchange. That is assuming the water you are filling with is the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose on bottom) and pull water from the top step.
Mmmmmm.... great information to have for sure. I would also like to know where to rent/purchase a sub pump as well for future reference.
 

Diannapool22

Well-known member
Aug 14, 2018
58
Scottsdale, AZ
Updated test numbers (with Speedstir) prior to draining:

FC= 38
CH= 1450
TA= 160
CYA= ~150 (can't see dark circle at bottom of viewing tube halfway to 100 line)
pH= 7.5

I needed some testing practice, maybe these are more accurate, although clearly not worth any significance
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,412
Laughlin, NV
So if I am filling/draining at 7gpm (420 gph), it's going to take 42 hours to turn over my 17,820 gal pool?
Yes. It is a slow process. If you want a quick one, rent a 2 hp sump pump from Home Depot. It will pump about 3-4000 gph. You will need to go to your street with it as your sewer cleanout will not take that rate. You will also be draining your pool. Keep the plaster wet as well as you can. Then put your hose in the pool and fill it. It will take about the same 40 hours or so.
 

Diannapool22

Well-known member
Aug 14, 2018
58
Scottsdale, AZ
Yes. It is a slow process. If you want a quick one, rent a 2 hp sump pump from Home Depot. It will pump about 3-4000 gph. You will need to go to your street with it as your sewer cleanout will not take that rate. You will also be draining your pool. Keep the plaster wet as well as you can. Then put your hose in the pool and fill it. It will take about the same 40 hours or so.
I think I'll just go the slow rate, have the flows matched and sewer clean out can handle the exit flow. We aren't supposed to run pool water in the street in Scottsdale according to the city website. Thanks for the info!
 

kimkats

Mod Squad
LifeTime Supporter
Jul 10, 2012
43,235
Tallahassee, FL
This is the safer way all the way around. Sure don't want someone showing up at your house asking about all of the water running down the road :shock: This also keeps your plaster protected.

You might need to do it a couple of times to get your numbers where they need to be.

For you CYA test do this for me:
-pull some pool water
-have some tap water ready
-put the same amount of pool water and tap water in a measuring cup. Maybe 1/4 cup of each. Mix it good
-now use the mixed tap/pool water for the CYA test.
-You will DOUBLE the number to find your CYA amount.

Doing the CYA test:
-GLANCE only!! Do not look for the dot. GLANCE in then look away.
-Pour to each line starting at 100. If you see the dot at a GLANCE then pour to the next line.

Kim:kim: