Cannot Get Chlorine / pH Levels Dialed In

[bbdude]

Hi All - I have an older 450 gallon CalSpa. Had a ton of water issues last winter because I wasn't staying on top of the chemicals. After owning a pool over the summer I've got a better understanding, but still struggling to get my chemicals dialed in. Hoping you can assist and tell me what I'm doing wrong.

1. Filled tub in October. Raised FC to 3. Purged with Ahhsome, twice.
2. Drained tub same day. Cleaned/wiped down. Refilled.

Since then I've struggled to maintain any FC levels and pH has been 8.2+ consistently. However, water looks great.

1. CYA is 45 so per FC/CYA calculator I decided to SLAM on Sunday (19th) by adding 10oz of 12.5% chlorine.
2. Today FC is back to zero (0). I SLAM again this morning.

From reading the forum it seems I'm treating SLAM as one and done and not testing multiple times a day to ensure SLAM level is being maintained until overnight test shows 1.0 ppm or less of FC loss. Going to do that going forward. I haven't figured out how to keep the pump running 24/7, unfortunately.

Does it make sense to try and get my pH down during the SLAM process or wait until it's done? Thanks in advance for any input.

Here are my readings pre-SLAM:
FC - 0
TA - 100
CYA - 45
pH - 8.2
CH - 425
CSI - 0.94
TEMP - 100

 

[Bperry]

Hi All - I have an older 450 gallon CalSpa. Had a ton of water issues last winter because I wasn't staying on top of the chemicals. After owning a pool over the summer I've got a better understanding, but still struggling to get my chemicals dialed in. Hoping you can assist and tell me what I'm doing wrong.

1. Filled tub in October. Raised FC to 3. Purged with Ahhsome, twice.
2. Drained tub same day. Cleaned/wiped down. Refilled.

Since then I've struggled to maintain any FC levels and pH has been 8.2+ consistently. However, water looks great.

1. CYA is 45 so per FC/CYA calculator I decided to SLAM on Sunday (19th) by adding 10oz of 12.5% chlorine.
2. Today FC is back to zero (0). I SLAM again this morning.

From reading the forum it seems I'm treating SLAM as one and done and not testing multiple times a day to ensure SLAM level is being maintained until overnight test shows 1.0 ppm or less of FC loss. Going to do that going forward. I haven't figured out how to keep the pump running 24/7, unfortunately.

Does it make sense to try and get my pH down during the SLAM process or wait until it's done? Thanks in advance for any input.

Here are my readings pre-SLAM:
FC - 0
TA - 100
CYA - 45
pH - 8.2
CH - 425
CSI - 0.94
TEMP - 100

First one, your CYA is either 40 or 50. Don’t bother trying to interpolate between readings because the FC level for CYA-41 is the same as CYA-50. So when you do the CYA test, just fill it up to each line and check the dot visibility. If you can still see it, fill it up to the next line.

And yes, SLAM is a process and not one and done. Read through the SLAM page carefully.

But with a tub, it seems like dumping water and starting over is usually way easier/cheaper. So consider that.

 

[bbdude]

But with a tub, it seems like dumping water and starting over is usually way easier/cheaper. So consider that.

Thank you! I'm hopeful in a couple days of staying on top of the SLAM process / algae it will be remediated. My worry is dumping won't remedy a possible algae issue in the pipes/jets.

 

[Bperry]

Thank you! I'm hopeful in a couple days of staying on top of the SLAM process / algae it will be remediated. My worry is dumping won't remedy a possible algae issue in the pipes/jets.

Nothing wrong with doing the slam or replacing the water. You might need to do a very short slam after replacing the water if there is stuff in the plumbing, but thats up to you. If you’re kind of new at this, then may be practicing a slam on the “bad“ water might be educational but it seems you’ve been around long enough that I can’t say that you’re new.

 

[JoyfulNoise]

Typically speaking, algae is not an issue in a hot tub. Bacterial and mold growth is more of the problem. Plus, you did an Ahhsome purge and so there is not, or should not be, anything in your plumbing.

Did you follow the purge instructions exactly and use the correct amounts? People tend to overdo it with Ahhsome thinking more is better and then they overdose the tub. Because it’s impossible to get all of the purge water out of the plumbing, that leaves a significant residual of the Ahhsome chemical behind. This can cause increased FC demand as the chlorine breaks down the residual Ahhsome. TFP recommends using a shop vac to get as much of the water out of the plumbing as possible and then try to use a small amount of water to blow out the lines using the spa pump. Users will go so far as to do a second flush of the plumbing with a full tub and then drain that too.

You can continue to SLAM but it’s not really a process well suited for hot tubs because the tub water temps are so high. You’ll find it hard to achieve an overnight chlorine loss of less than one unless the tub is shut off and allowed to cool a bit. It easier to just maintain a higher level of FC until you see the daily loss rate decrease. That means babysitting the tub for a bit while you test daily and replenish the FC.

 

[bbdude]

Nothing wrong with doing the slam or replacing the water. You might need to do a very short slam after replacing the water if there is stuff in the plumbing, but thats up to you. If you’re kind of new at this, then may be practicing a slam on the “bad“ water might be educational but it seems you’ve been around long enough that I can’t say that you’re new.

You were right. I couldn't keep up with the chlorine. FC went from 20 to 11 just overnight. Dumped today and replacing water now. Will SLAM tonight to be safe.

Typically speaking, algae is not an issue in a hot tub. Bacterial and mold growth is more of the problem. Plus, you did an Ahhsome purge and so there is not, or should not be, anything in your plumbing.

Did you follow the purge instructions exactly and use the correct amounts? People tend to overdo it with Ahhsome thinking more is better and then they overdose the tub. Because it’s impossible to get all of the purge water out of the plumbing, that leaves a significant residual of the Ahhsome chemical behind. This can cause increased FC demand as the chlorine breaks down the residual Ahhsome. TFP recommends using a shop vac to get as much of the water out of the plumbing as possible and then try to use a small amount of water to blow out the lines using the spa pump. Users will go so far as to do a second flush of the plumbing with a full tub and then drain that too.

You can continue to SLAM but it’s not really a process well suited for hot tubs because the tub water temps are so high. You’ll find it hard to achieve an overnight chlorine loss of less than one unless the tub is shut off and allowed to cool a bit. It easier to just maintain a higher level of FC until you see the daily loss rate decrease. That means babysitting the tub for a bit while you test daily and replenish the FC.

I did it by the letter and after it was done ... I dumped the water, cleaned the tub w/ shopvac, and refilled. I think my error was not SLAMing when I refilled.

 

[Mdragger88]

Keep in mind that it’s generally not possible to pass an
Overnight Chlorine Loss Test with a 1ppm or less loss in hot tub because the continual fc demand is just so much higher in a spa.
The loss you described does seem a bit high though.
But The rest of the
SLAM Process still holds true - continue until the water is crystal clear & cc’s are 0.5 or less.
Generally we recommend going a few rounds of slam level & if that doesn’t do the trick just go on & dump & start fresh. Much easier & faster than fighting with it.
Hopefully your fresh start should do the trick
Be sure now to keep on top of chlorine.
As mentioned the tub eats continuously so you must ensure that fc never falls below minimum for your cya lest nasties will grow & you’ll be behind the 8ball again.
FC/CYA Levels
This means testing frequently & replenishing fc before & after use & on days when you don’t use the tub.

 

[bbdude]

Thank you, @Mdragger88 ... I only lost 1-2FC overnight so looks like I'm in good shape. Will check again this afternoon.

How much FC would you add before / after use? 1oz of liquid?

Also, I'm leaving for 10 days. Should I just SLAM before I leave?

 

[Mdragger88]

Thank you, @Mdragger88 ... I only lost 1-2FC overnight so looks like I'm in good shape. Will check again this afternoon.

That doesn’t sound too terrible & like you’re on the right track -
what are the cc’s?
How does the water look? Those are your defining hallmarks as to whether you have succeeded.
If all that is good (.05 or less cc’s & Crystal clear)
then hopefully it was just some residual funk that you had to knock out.

How much FC would you add before / after use? 1oz of liquid?

If using 12.5% that would yield you 2.2 fc in your 450 gal tub
That may or may not be enough depending upon your starting fc level & depending upon how long your soak is & how many people.
You will need to test before & after using the tub to get an idea of your average bather load consumption.
For reference I have a tub that’s 1/2 the size of yours & I can go through 2ppm in a 30 minute 1 person soak. Ymmv.
Don’t be afraid to test mid soak & add more if needed until you figure out what you need for your regular sessions to ensure you don’t fall below minimum.

Also, I'm leaving for 10 days. Should I just SLAM before I leave?

That’s really your only option without someone to dose for you while you’re gone. Many can get by for a week with that but 10 days may be a stretch. Only time will tell. You really don’t have a baseline yet for what your standby consumption is so work on figuring that out until you leave.
Many people just use their daily consumption x’s however many days they will be gone + a ppm or two of a buffer.

*Turning the heat down should help lower the fc & electric consumption while you’re away.

 

[bbdude]

That doesn’t sound too terrible & like you’re on the right track -
what are the cc’s?
How does the water look? Those are your defining hallmarks as to whether you have succeeded.
If all that is good (.05 or less cc’s & Crystal clear) then hopefully it was just some residual funk that you had to knock out.

Tested FC 16 hours ago and it was 22. Right now FC is 17 and CC is negligible. Water is clear/normal.

Seems like there's still something in the water, right? CYA is 40. Should I just continue to SLAM or is a change of 5 FC in ~24 hours sensible? Seems too fast a drop. Water temp is 100.

 

[Mdragger88]

The higher the fc level the faster the drop so the rate of loss may be noticeably reduced as the fc lowers. With nil cc’s & clear water I would just use the tub & keep fc a little elevated while monitoring it.
Many people find they need to dose somewhere between high target & slam after use to make up for their current bather load & also get through to the next test/dose/use.
Example:
If cya is 50 :

Then after your soak dose some where between high target & slam. Perhaps 10 or 12 ppm - This should allow you to make it to the next day & fc be within target range and likely have enough fc to get through your next soak (if its average)without falling below min. All these exact numbers will need to be tailored to your actual needs & use & be based on what you find with your testing.
This is just an example of how you might find your groove if you use the tub every day & in pretty much the same way most times. Otherwise you just adjust accordingly.
I always test before using the tub to confirm my fc is where it needs to be & adjust the fc & ph if necessary at that time. Then after use I do as I described above only I need to use a little less since I have a swcg that takes care of my standby fc needs.
(High target is generally high enough for me).

You’ll need to test often at first to figure out what you need. There’s not an exact recommendation of “x” amount of bleach - there’s only what your tub needs when it needs it. I am sure you can see how the “just add x amount of this x times a week” recommendations could get you in trouble quickly here.
Btw- If your cya reads between 2 values always round up for chlorination purposes.

 

[bbdude]

Thank you, @Mdragger88 . Going to test every 12 hours or so and see where I'm at come end of week. Right now we use the hot tub once a week or less so it's really a pain testing daily and adjusting etc for how little we use it. But that's a me problem haha. We inherited the tub so it's not loved like the pool haha.

 

[Mdragger88]

Thank you, @Mdragger88 . Going to test every 12 hours or so and see where I'm at come end of week. Right now we use the hot tub once a week or less so it's really a pain testing daily and adjusting etc for how little we use it. But that's a me problem haha. We inherited the tub so it's not loved like the pool haha.

You’re looking at it wrong- when pool season ends real hot tub season begins!
I do have to make a point to get my hot tub time in sometimes, sorta like any exercise in wellness, but I am always glad afterwards that I did! Hopefully it will grow on you

 

[bbdude]

You’re looking at it wrong- when pool season ends real hot tub season begins!
I do have to make a point to get my hot tub time in sometimes, sorta like any exercise in wellness, but I am always glad afterwards that I did! Hopefully it will grow on you

Haha. It's the showering at the hot tub (or pool) that gets me since I'm cramped for time. Need to start taking a dip after my workouts!

It's been ~9 hours since the last FC test and I'm down from 16 to 11. Slowing down now at least. Target is 6-8 w/ CYA of 50. We'll see where things are tomorrow morning.

 

[bbdude]

Just a little over 12 hours since last FC test and I'm still at 11 so no change! Good news. Will test again tonight ... hopefully back to steady now and can focus on my pH, which really doesn't want to go down at all haha.

 

[Mdragger88]

Just a little over 12 hours since last FC test and I'm still at 11 so no change! Good news. Will test again tonight ... hopefully back to steady now and can focus on my pH, which really doesn't want to go down at all haha.

When testing ph & dosing with acid be sure to retest in 15 minutes or so. If you wait a while ph will have risen again.
This can happen fairly quickly with a ta of 100 in a spa.
As you dose with acid your ta will lower each time. As the ta gets lower & lower the ph rise will slow. Most people find ph much easier to manage in their spa when ta is around 50/60. Just aim for mid 7’s with the ph & you’ll get there eventually.

 

[bbdude]

When testing ph & dosing with acid be sure to retest in 15 minutes or so. If you wait a while ph will have risen again.
This can happen fairly quickly with a ta of 100 in a spa.
As you dose with acid your ta will lower each time. As the ta gets lower & lower the ph rise will slow. Most people find ph much easier to manage in their spa when ta is around 50/60. Just aim for mid 7’s with the ph & you’ll get there eventually.

Thanks! With my pool I'd add acid (MA) each day until the pH is down where I want it. Should I be more aggressive with acid (dry acid) in the tub? Maybe twice a day?

 

[Mdragger88]

Thanks! With my pool I'd add acid (MA) each day until the pH is down where I want it. Should I be more aggressive with acid (dry acid) in the tub? Maybe twice a day?

Test - dose to target (mid 7’s) then test again in 15 minutes or so & dose again if necessary to get to a readable ph, repeat until you reach your target. If you’re waiting until the next day ph will surely have risen again & it will seem as if your dose was ineffective.
My start up ta is 100-110 & if I stay on top of it (aerating & lowering ph) I can get ta down to 50/60 in a day in my spa.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.google.com

P.s. - using muriatic acid is recommended, dry acid adds sulfates which are not good for your swcg or your other equipment/surfaces (plaster).

 

[bbdude]

Thanks, @Mdragger88 ! I was just about out of Dry Acid so your post stopped me. Going to get some MA instead. I don't have time during the week to monitor the pH, but will get it dialed in this weekend. Would be great to solve it in a day!

Chlorine still holding. Dropped down to normal levels today. So we'll see what the 'burn rate' looks like. I think for my days away this month I may just put the tub in energy saver mode, which drops water temp to 70 so hopefully SLAM will keep chlorine in the tub over the 10 day span.

 

[bbdude]

Test - dose to target (mid 7’s) then test again in 15 minutes or so & dose again if necessary to get to a readable ph, repeat until you reach your target. If you’re waiting until the next day ph will surely have risen again & it will seem as if your dose was ineffective.
My start up ta is 100-110 & if I stay on top of it (aerating & lowering ph) I can get ta down to 50/60 in a day in my spa.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.google.com

P.s. - using muriatic acid is recommended, dry acid adds sulfates which are not good for your swcg or your other equipment/surfaces (plaster).

This eventually works. My pH has been around 7.5 for a few days now ... finally! Thank you!

However, my TA is really low now @ just 20. Should I just leave it there or add baking soda to get it up?