New Tub, crazy water. Perhaps a little help out there?

Livesprings

Member
Feb 10, 2021
7
Illinois
Hello! Recently got a brand new spa! 400 gallon 94x94. This forum is awesome, glad to have found it.

Here is my crazy water chemistry ordeal. All levels have been awesome since we have had the spa, been testing daily, sometimes multiple times daily, with a Taylor test kit. Chlorine around 3 PPM, alk about 80-90, ph just above 7. We’ve simply been adding about 1 tsp dichlor after each use, mostly just 2-3 people in tub during evenings or just my wife and I. I’ll check it first thing in morning, if chlorine is low, I’ll add a tsp or less of dichlor. Last night daughter had 4 teenagers in it, they just sat and talked for about an hour, nothing crazy. I read about benefits of non-chlorine oxidizer so I put in 2 ounces of potassium peroxymonosulfate last night for the first time, instead of chlorine, after they got out. I went out this morning to test chlorine and it was very very low so added 2 tsp dichlor. At lunch today decided to test combined chlorine and it was 6, which I read is very high. So I went on to test the alk and it went from 80-90 every day down to 20 seemingly overnight. I thought to myself, holy cow, and tested the PH. The ph went from just above 7 every day down to off the charts low. The water still looks clear as can be and there is very very little smell when lifting the cover, smells about like city tap water. I was going to start with adding baking soda but then it occurred to me that I should ask for guidance before proceeding. Any ideas out there? Did the non chlorine oxidizer crest a problem? Should I just start with the baking soda and move on to the Ph, then work on getting the combined chlorine down? Or should I just wait until all the oxidizer is gone (if it isn’t already) and test again? THANKS!
 

CuckooChris

Well-known member
Sep 14, 2016
83
Coplay, PA
You have come to the right place! Do read the link at the top of the forum. We will also need more information like, what exact model test kit do you have and does the spa have ozone? Lots to learn here, ozone will eat chlorine, non chlorine oxidizer like MPS will affect some test readings and too much dichlor will raise CYA.
 

Livesprings

Member
Feb 10, 2021
7
Illinois
Hello! Recently got a brand new spa! 400 gallon 94x94. This forum is awesome, glad to have found it.

Here is my crazy water chemistry ordeal. All levels have been awesome since we have had the spa, been testing daily, sometimes multiple times daily, with a Taylor test kit. Chlorine around 3 PPM, alk about 80-90, ph just above 7. We’ve simply been adding about 1 tsp dichlor after each use, mostly just 2-3 people in tub during evenings or just my wife and I. I’ll check it first thing in morning, if chlorine is low, I’ll add a tsp or less of dichlor. Last night daughter had 4 teenagers in it, they just sat and talked for about an hour, nothing crazy. I read about benefits of non-chlorine oxidizer so I put in 2 ounces of potassium peroxymonosulfate last night for the first time, instead of chlorine, after they got out. I went out this morning to test chlorine and it was very very low so added 2 tsp dichlor. At lunch today decided to test combined chlorine and it was 6, which I read is very high. So I went on to test the alk and it went from 80-90 every day down to 20 seemingly overnight. I thought to myself, holy cow, and tested the PH. The ph went from just above 7 every day down to off the charts low. The water still looks clear as can be and there is very very little smell when lifting the cover, smells about like city tap water. I was going to start with adding baking soda but then it occurred to me that I should ask for guidance before proceeding. Any ideas out there? Did the non chlorine oxidizer crest a problem? Should I just start with the baking soda and move on to the Ph, then work on getting the combined chlorine down? Or should I just wait until all the oxidizer is gone (if it isn’t already) and test again? THANKS!
At the top of the spa forum is the following link that will guide your use of chlorine in your spa.
Check this out.... How do I use Chlorine in my Spa (or pool)?
At the top of the spa forum is the following link that will guide your use of chlorine in your spa.
Check this out.... How do I use Chlorine in my Spa (or pool)?
Thanks! Nitro’s method was what we were trying to stick with originally. Lol. Just need to re-read and do a better job. I did go ahead and add 6 tablespoons baking soda and dichlor last night... this morning all the levels look great again! Thanks again, appreciate the help.
 

Livesprings

Member
Feb 10, 2021
7
Illinois
You have come to the right place! Do read the link at the top of the forum. We will also need more information like, what exact model test kit do you have and does the spa have ozone? Lots to learn here, ozone will eat chlorine, non chlorine oxidizer like MPS will affect some test readings and too much dichlor will raise CYA.
Thanks, CuckooChris. As I told
You have come to the right place! Do read the link at the top of the forum. We will also need more information like, what exact model test kit do you have and does the spa have ozone? Lots to learn here, ozone will eat chlorine, non chlorine oxidizer like MPS will affect some test readings and too much dichlor will raise CYA.
Thanks, CuckooChris. As I told Oly, I did go ahead and add 6 tablespoons baking soda and dichlor last night... this morning all the levels look great again! I’ll be trying to do a better job of sticking with Nitro’s method from here on out. Thanks again!
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,390
Tucson, AZ
Pool Size
16000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
What “benefits” of MPS are you reading about?

As you just discovered, MPS not only gave you a false high CC reading (it messes up the FAS-DPD test) but it’s also acidic enough to drop pH and TA, although not as much as you report so there’s something else going on. As well, MPS adds sulfates to your water which are bad for heaters.

I suggest you stop using the MPS and go back to following the dichlor-then-bleach method and leave all the “magical” chemicals at the pool/spa store.

Also, even if it is a new tub, you should purge the plumbing with Ahhsome on the next drain/refill. The plumbing likely has junk (biofilms) built up in it.
 
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Livesprings

Member
Feb 10, 2021
7
Illinois
What “benefits” of MPS are you reading about?

As you just discovered, MPS not only gave you a false high CC reading (it messes up the FAS-DPD test) but it’s also acidic enough to drop pH and TA, although not as much as you report so there’s something else going on. As well, MPS adds sulfates to your water which are bad for heaters.

I suggest you stop using the MPS and go back to following the dichlor-then-bleach method and leave all the “magical” chemicals at the pool/spa store.

Also, even if it is a new tub, you should purge the plumbing with Ahhsome on the next drain/refill. The plumbing likely has junk (biofilms) built up in it.
Amen. Well said and I agree. Thanks!
 
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