New hot tub, trying to set a routine

random-words

Member
Nov 11, 2021
7
Saint Louis, MO
We have a hot tub/swim spa combination and have had it for a month now. The hot tub side is 425 gal and the swim spa side is 2100 gal. The hot tub temperature is kept around 100 while the swim side is at 90. The cover is on both sides almost all of the time. The hot tub gets the most use (in this weather), generally after dark. So there is little or no sunlight hitting the water.

The default filter settings have the pumps running two hours a day in the evening. I can change this schedule, but I don't know what it should be.

When I check the swim side water, the chemical levels tend to read in expected ranges, except the FC is usually zero. Then I add chlorine (currently using the dichlor granules sold by the pool store, have read about using bleach and will be adjusting that) This could be because the swim side goes days without me checking anything. Again, this is new and I'm not sure what I should be doing or when.

The hot tub side is... well, it's a hot mess. The water is consistently cloudy, the FC keeps dropping to zero despite being adjusted and shocked, the pH bounces all over the place and it's foamy. When I got my TF Test Kit (just came in a few days ago), I measured TA at 50. I weighed out what should have been the correct amount of alkalinity increaser (still using the chemicals the pool store sold me, I know I should be using baking soda going forward) based on the TA measurement and the spa size. Despite that, the TA is now reading around 150. Yesterday, the pH was low (below the bottom of the scale) so I raised it. Then this morning, the pH was reading about 8.4 so I added pH decreased (again, the pool store chemicals). I got the pH to read closer to 7.8. I have no idea what it will be next time. Despite adjusting the TA, the pH continues to bounce. Today after adjusting the pH I added a non-chlorine shock and after about 30 minutes a few tablespoons of the dichlor granules. I'll check it later. It's still cloudy. CYA tested at 10. I don't have anything on hand to adjust that right now.

We are about to leave town for a week so the system will not be touched. No one will be checking or adjusting chemicals. I will be buying the recommended chemicals when I return. I don't know whether to allow the neighbors to use the hot tub while we're gone. I'm not sure the water quality is in a good enough place, and they don't know how test or adjust it.

Any recommendations?? I know that's a lot.
 

Mdragger88

Bronze Supporter
Jun 1, 2018
3,341
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
If you have let the fc drop to zero multiple times in either body of water you likely need to do an Ahhsome purge & start fresh using this guide 👇
You may just be able to do the SLAM Process on each side but it’s much easier & faster to just start fresh with smaller bodies of water.
You added ta increaser (which is just expensive baking soda)
Then u added something (possibly sodium carbonate- which is super washing soda/soda ash) to increase ph which undoubtedly also raised ta some more. Apparently to 150ppm. Aeration would have worked fine to increase ph without increasing ta.
The now higher ta coupled with the aeration present in a spa will cause ph to rise frequently. Its no big deal just lower ph to the mid 7’s when it gets to 8. Retest about 15 minutes or so after adding acid to confirm it lowered to your target & if it didn’t it could be because your ph was actually higher than 8 so u just need to do it again until u get a reading in the 7’s.
The ta will eventually lower overtime- unless it’s below 50 there’s no need for baking soda.
When you add dichlor it not only adds fc but also cya as well as lowering ph.
See PoolMath effects of adding for the effects each dose of dichlor (or any chemical) has prior to adding to get an understanding.
How are u getting a cya of 10ppm? The tf100 cya test doesn’t go that low. It may actually be just below 20
For Every 10ppm of fc dichlor adds it also adds about 9ppm of cya to the water.
Can u remember approximately how many ppm of dichlor you have added to come up with a guesstimate of your current cya? This way you will know you are chlorinating to the proper shock level.

Both bodies of water need to be tested & dosed w/ chlorine every day to maintain fc levels above minimum for their cya FC/CYA Chart at all times lest nasties will grow. Not just when u want to use them.
The smaller & hotter the body of water the faster things can get out of hand especially with a high bather load like a spa.
The spa fc should be tested & dosed (if necessary) before & after use until u get a feel for what each bather load does to the fc level. Many people are able to dose to shock/slam level for their cya after use & still have enough residual fc left by the next day when they wish to use the tub again. The pool is a bit bigger so the demand may be less especially with it being covered most of the time but it’s fc level still needs to be maintained at all times.
I would not recommend anyone use them until u get them cleaned up especially if no one will be adding chlorine to keep it in range while u are gone. Person to person transmission of pathogens is no joke.
To summarize:
📌 Either purge & refill or SLAM Process to correct the water conditions after which 👇
📌 - Keeping fc above minimum for your cya at all times is paramount - switch to bleach when cya reaches 30ppm to keep it from becoming unsustainable
**Always follow the FC/CYA Chart**
📌 Ph rise in a spa is inevitable, test it daily or so & add enough acid to keep it in the 7’s - if it accidentally falls a little low aeration (running the jets) will increase ph without increasing ta further
📌Ta isn’t necessary to worry with too much unless it falls below 50ppm
 
  • Like
Reactions: jseyfert3

jseyfert3

Silver Supporter
Bronze Supporter
TFP Guide
Oct 20, 2017
1,878
Southern WI
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
First off, welcome to TFP! @Mdragger88 posted while I was still composing but I'm going to post my reply anyway. :LOL:

We are about to leave town for a week so the system will not be touched. No one will be checking or adjusting chemicals. I will be buying the recommended chemicals when I return. I don't know whether to allow the neighbors to use the hot tub while we're gone. I'm not sure the water quality is in a good enough place, and they don't know how test or adjust it.
No, definitely do not let them use it. Hot tubs are at the perfect temp for all sort of bacteria and such to grow. They require proper sanitation to avoid transmission of disease. You already have things growing (the cloudy water indicates this), and with not adding anything it would be a recipe for disaster.

Don't worry, once you get back we'll help you get your hot tub nice and clean. Here's a picture of mine:
full


When I check the swim side water, the chemical levels tend to read in expected ranges, except the FC is usually zero. Then I add chlorine (currently using the dichlor granules sold by the pool store, have read about using bleach and will be adjusting that) This could be because the swim side goes days without me checking anything. Again, this is new and I'm not sure what I should be doing or when.
If you check FC and it is 0, that means you have to add chlorine more regularily than you do. The goal is to not let the FC drop to 0 ever. Here at TFP we've outlined a relationship between CYA and desired FC levels. This is a little different than some FC recommendations you've likely seen elsewhere, but it's due to how chlorine effectiveness is reduced by CYA, and is backed up by lots of math and experience of thousands of users on TFP.

The hot tub side is... well, it's a hot mess. The water is consistently cloudy, the FC keeps dropping to zero despite being adjusted and shocked, the pH bounces all over the place and it's foamy. When I got my TF Test Kit (just came in a few days ago), I measured TA at 50. I weighed out what should have been the correct amount of alkalinity increaser (still using the chemicals the pool store sold me, I know I should be using baking soda going forward) based on the TA measurement and the spa size. Despite that, the TA is now reading around 150. Yesterday, the pH was low (below the bottom of the scale) so I raised it. Then this morning, the pH was reading about 8.4 so I added pH decreased (again, the pool store chemicals). I got the pH to read closer to 7.8. I have no idea what it will be next time. Despite adjusting the TA, the pH continues to bounce. Today after adjusting the pH I added a non-chlorine shock and after about 30 minutes a few tablespoons of the dichlor granules. I'll check it later. It's still cloudy. CYA tested at 10. I don't have anything on hand to adjust that right now.
So, first off, if you have cloudy water the best thing to do is purge, drain, and refill. I personally recommend Ahh-Some. I don't get paid for saying that, I've just used it and it works, and works well. I recommend you get some on order so you can purge after you get back from your trip before draining and refilling.

TA at 50 is actually just about perfect for following TFP guidelines for maintaining your spa water. pH "bounce" and TA is a little misunderstood. Yes, TA is a buffer and this means you need more acid to affect the same amount of pH change. However, what's NOT commonly discussed is the higher the TA is, the faster the pH naturally climbs due to aeration, and hot tubs have a LOT of aeration. So counter-intuitively for non-TFP advice, a high TA usually ends up resulting in more pH "bounce", not less.

I'll stop there and let you digest these two posts, then ask any questions you'd like. We're here to help!
 
  • Like
Reactions: Mdragger88

random-words

Member
Nov 11, 2021
7
Saint Louis, MO
Merged threads - TFP Mod
Hot tub: 425 gal, ozonator with UV light, temp around 101 F, regular use
Swim spa: 2100 gal, ozonator, temp around 90 F, limited use during winter

I've had this system since October. Initially, I went to a pool store and was sold a bunch of expensive chemicals with somewhat cryptic instructions and the directive to come back to them with water samples. I didn't go back. I've used up the dichlor and switched to bleach (8.25%). I still have dry acid and alkalinity increaser (aka expensive baking soda).

I've been reading this forum and trying to make sense of what to do, what levels to maintain and then reconcile that with what's actually happening in the water.

The swim spa side tends to hold onto FC. Again, it gets little use. I'm not concerned about it right now.

The hot tub side keeps getting out of whack, and after reading more posts in the spa forum, I think I may have been treating it like a pool, not a hot tub. After about a month, we drained and refilled the hot tub. The water was cloudy and foamy, and even smelled funny. Levels were all over the place. For the first drain, I thoroughly hosed off the filter (which also smelled funny and the water coming off of it was foaming). I've been more careful since the second fill, but FC keeps going to zero. It was just today that I realized that the ozonator is likely doing that, and also just today that I read that we need to add bleach IMMEDIATELY AFTER each bathing session. It's cold out, and we haven't wanted to stand there dripping in the cold and add bleach. But apparently this has to be done.

A few specific questions:

CYA: Both sides were initially chlorinated with dichlor. Now I'm using bleach. I haven't been able to find CYA on the shelves anywhere. When asking about pool chemicals at hardware stores in December, I'm getting some weird looks. I guess I need to visit a pool store. But do I actually need CYA? Both sides are covered. The cover is quite heavy and seals pretty well. On days when it's not used, I only uncover long enough for a chemical check. Most usage of the hot tub is after dark since the sun sets so early. We've had just a few daytime usage sessions, usually not more than a few hours. So the sunlight hitting the water is barely a thing. What CYA level, if any, should I be targeting? And how exactly do I "hang a sock in front of the return"? There is no place to hang anything and the returns are at the bottom of the spa.

Total Alkalinity: My previous pool experience (above-ground outdoor, about 20 years ago) tells that that TA has a sweet spot and I need to find that and keep it there (once there, it should maintain itself). I don't think I've found it yet. When I raise the TA to around 100, pH rises fast and won't stay down. I realize the aeration is contributing to the pH rise. TA is currently closer to 60. Is there a specific TA target suited for a spa?

Calcium hardness: do I care? Is there any point to measuring this?

Line purge: I just read today about this Aaahsome purge. Do I need to do this? If so, how often? Does it need to be drained? The spa was brand-new two months ago.

Filter cleaner: I've been spraying out the filters and then putting them back in. Do I need to soak the filters in something? If so, what? How often? The filters are very tall and I'm not sure where to get a tall-enough bucket.

SLAM: Right now I'm slamming the hot tub. The water had become cloudy and the FC keeps dropping to zero. Today the CC read 1.0 with FC 0, so I think it definitely needs it. How different is the SLAM instruction for a hot tub with ozonator?

Filter cycles: I have absolutely no idea what the filter cycles should be. The default is 2 hours/day and I left it scheduled that way. When I add chemicals, I turn on the jets and those run for 30 minutes before turning off. The heater pump will come on whenever necessary. The pool I had at a previous house (above-ground) ran the filter 24/7 during pool season because it was getting constant tree debris. I think the sweet spot for this system is somewhere between those, but I don't know where to start.

Vacuuming: The filter has a sort of skimmer, but it doesn't get leaves that landed at the bottom of the spa. And when I drained it once, the water at the very bottom (and its leaves) didn't drain (it's just a few inches of water below the returns). Should I have a vacuum for the spa? What kind? Buy at pool store or online? While the swim side isn't dirty now, it has a lot more surface area than the spa and might need a pool-sized vacuum setup once it gets heavier use in summer.

Sorry for the very long post... just trying to get a stable routine down and some predictable targets to hit.
 
Last edited by a moderator: